Fabric Shrinkage: Why It Happens and How to Control It

Shrinkage is a change in the length or width of a fabric or garment. Cotton Incorporated, in ISP 1009, defines that change as able to go in a positive direction (growth) or a negative one (shrinkage). In a later CottonWorks webcast, Overcoming Shrinkage, the same organisation adds a mill definition: shrinkage or growth is the difference in dimensions between the delivered state of a fabric or garment and its reference state, the fully relaxed condition in which it will not change further as a result of washing and tumble drying.

Knitted fabrics of all constructions and fibre blends are inherently more prone to shrinkage than wovens, Cotton Incorporated states in TRI 3011, and a cotton knit is easily distorted in processing.

Yarn count, stitch length and machine gauge set the tightness of a weft knit and therefore much of its construction shrinkage; see Yarn Count Systems Explained. Fabric mass is GSM, which will itself change if the cloth shrinks. Single jersey is particularly liable to skew as well as to length change; see Single Jersey vs Rib vs Interlock. Laboratory fabric tests more generally are covered in Fabric Testing: Methods, Equipment and What Results Mean.

Self-made diagram for this article. The three cotton mechanisms follow Cotton Incorporated, ISP 1009. Felting follows The Woolmark Company, Machine Washable Wool.

Why fabrics shrink

For cotton, ISP 1009 divides shrinkage into construction shrinkage and processing shrinkage. Construction shrinkage comes from the yarn and the way the fabric was made, and it can be measured on greige cloth before later processes. Processing shrinkage is what dyeing, finishing and apparel manufacture add to or remove from that construction shrinkage, and so change the residual shrinkage. Residual shrinkage is what remains after a process has stretched or compressed the cloth.

Several mechanisms sit inside those two headings.

Elastic, or relaxation, shrinkage is a change in dimensions as the fabric freely relaxes from tensions experienced during construction and later processing. On a cotton greige knit, ISP 1009 cites tensions in forming the knitted loop and from the take-down and spreader, and also stresses in bleaching, dyeing and finishing.

Swelling and drying shrinkage need more energy. When a cotton fabric wets out without tension, the fibres and then the yarns swell. ISP 1009 explains that the crimp in the yarn loops increases, and the loops try to assume a more round, lower-energy shape. That rounding shortens the loop and the fabric changes dimension. In drying, the structure deswells and shrinks upon itself. Bound water acts as a lubricant, and mechanical action then produces still more shrinkage. The greatest relaxation occurs at moisture levels below 20 per cent, a point ISP 1009 calls critical moisture; drying shrinkage normally needs more energy than elastic shrinkage. It may take several wet-and-dry cycles to reach fully relaxed dimensions, although one cycle may remove around 90 per cent of the total shrinkage available.

Consolidation is the name ISP 1009 gives to processes that force or allow the structure to contract. Relaxation drying and compaction are the two examples. Relaxation drying occurs by deswelling under unrestricted agitation with no length or width tension. Compaction is a dry mechanical effect gained by forcing the structure to compact upon itself.

Felting is a wool mechanism, not a cotton one. The Woolmark Company explains that untreated wool fibres have microscopic scales on their surface. When the fibres are exposed to heat and moisture the scales lift, and with mechanical agitation they lock onto the scales of other fibres in a ratchet-like way.

Cotton Incorporated’s webcast makes a further point that is easy to miss: the actual shrinkage of the yarns is very small and is not significant to fabric shrinkage, except for fibres that are sensitive to heat. The conversion of yarns into fabric creates stress, and that stress creates openness in the structure, tightness factor in knits or cover factor in wovens, which later relaxation can close up.

Knits and wovens, cotton, wool and synthetics

Woven fabrics are much more stable than knitted fabrics and do not react as severely to stresses, ISP 1009 states, but the shrinkage specifications demanded of wovens are often much lower, so processing stresses still matter. In a knit, TRI 3011 says the amount of shrinkage depends mainly on the product specifications and the knitting parameters used to meet them: the sold weight, stitch counts and width, and then the yarn count, gauge, number of needles and stitch length. For a given yarn count, knitting a smaller loop results in a heavier, more stable fabric, with less length shrinkage but higher width shrinkage for any specified finished width.

Cotton is not stabilised by heat. The CottonWorks webcast puts it plainly: heat does not shrink cotton fabrics. Excess heat may cause yellowing, a stiffer hand or slower re-wetting, but not shrinkage. The question-and-answer paper adds that cotton cannot be set at a temperature in the way polyester can. Polyester, nylon and elastane are heat-settable, and fibres such as spandex can shrink with heat, but in a cotton–spandex blend heat setting is only effective on the spandex; there is normally not enough spandex to stabilise the fabric against shrinkage, although heat and time can drastically affect stretch and growth. High heat on cotton blends can also reduce absorbency and give a drier hand.

Wool can felt as well as relax. Machine-washable treatments, which Woolmark describes under the industry term Superwash, improve shrink resistance by removing or smoothing scales, reducing inter-fibre friction, or both. The widely commercialised Hercosett route is a chlorine pre-treatment followed by a polyamide-epichlorohydrin resin that bonds to the fibre surface. Superwash is a category; Hercosett is one technology within it.

How shrinkage is tested

A laboratory dimensional-change test has three parts: the specimen is prepared, marked and measured; it is washed and dried under a specified procedure; and the change is then determined.

ISO 3759:2011, confirmed in 2022 and also adopted as EVS-EN ISO 3759:2011, specifies the preparation, marking and measuring of textile fabrics, garments and fabric assemblies for tests of dimensional change after a specified treatment, for example washing, dry cleaning, soaking or steaming, following procedures in ISO 3005, ISO 7771, ISO 6330, ISO 3175 or ISO 15797. The official abstract states that it applies to woven and knitted fabrics and made-up textile articles, but not to certain upholstery coverings.

ISO 6330:2021, also EVS-EN ISO 6330:2021, specifies domestic washing and drying procedures for textile testing, including reference detergents and ballasts. The official abstract provides for 16 washing procedures on a Type A horizontal-axis, front-loading reference machine, 12 on a Type B vertical-axis, top-loading agitator machine, and 7 on a Type C vertical-axis, top-loading pulsator machine. Each washing procedure represents a single domestic wash. Six drying procedures are specified: line dry, line drip dry, flat dry, flat drip dry, flat press, and tumble dry. A complete test consists of a washing and a drying procedure, and different machine, detergent or dryer parameters can affect results.

ISO 5077:2007, confirmed in 2022 and adopted as EVS-EN ISO 5077:2008, specifies a method for determining the dimensional change of fabrics, garments or other textile articles after an appropriate combination of those washing and drying procedures. The EVS catalogue page adds a caution from the standard’s scope: in the case of textile articles or deformable materials, it is necessary to exercise all possible caution in the interpretation of the results. That caution matters for knits. The official catalogue pages do not publish the calculation clause of ISO 5077, so no rounding rule from that clause is quoted here.

In North American work the usual fabric method is AATCC TM135-2025, Dimensional Changes of Fabrics after Home Laundering. The official store abstract states that it determines length and width changes of fabrics after home laundering, with four washing temperatures, three agitation cycles and four drying procedures, and that it applies to all fabrics suitable for home laundering. AATCC TM150-2025 is the companion method for garments; its abstract uses the same wash and dry options, and notes that it may not apply to garments made of certain stretch fabrics. ISP 1009 describes the principle of AATCC TM135 as a tensionless wash followed by tumble drying that deswells and fully relaxes the fabric or garment.

Self-made diagram for this article. The roles of ISO 3759, ISO 6330, ISO 5077, AATCC TM135 and TM150 are taken from the official catalogue abstracts. The worked percentages are arithmetic illustrations of the Cotton Incorporated definition (a percentage of the initial dimensions), not a measured fabric.

How to calculate the percentage

Cotton Incorporated’s webcast states that, in the testing laboratory, dimensional change is expressed as a percentage of the initial dimensions of the specimen. The change can be a growth, an increase of the length or width, or a shrinkage, a decrease of those dimensions. Some products shrink in one direction and grow in the other.

The CottonWorks Q&A is explicit that shrinkage numbers are for one direction only. Each direction must be measured and listed separately. The numbers are not added to each other, and they are not averaged. The example given there is that 5 × 5 per cent means 5 per cent in the length and 5 per cent in the width.

A worked arithmetic illustration, using that definition, is as follows. A marked length of 250 mm is measured again after the specified wash and dry and is 240 mm. The change is a decrease of 10 mm, or 4 per cent of the initial 250 mm, reported as a 4 per cent shrinkage. A marked width that increased from 250 mm to 255 mm would be a 2 per cent growth. The two results are reported separately. AATCC sells a shrinkage scale that reads percent change directly, but the official TM135 and TM150 abstracts do not themselves print a formula.

How far one wash cycle takes you towards the reference state depends on the product and the method. ISP 1009 states that one cycle may remove around 90 per cent of the total shrinkage available, and that several cycles may be needed for fully relaxed dimensions. The webcast describes five home-laundry tumble dries as a practical route to the reference state, with three such cycles accounting for 95 per cent of the shrinkage.

How to control it

TRI 3011 lists four influences on dimensional stability: knitting parameters, processing tensions after knitting, relaxation techniques in finishing, and mechanical and chemical finishes. The CottonWorks webcast similarly asks for specifications of weight, cut-and-sew width and allowable shrinkage, and says that drying under the lowest tensions with maximum mechanical action, together with compaction and resin finishing, will reduce shrinkage.

Start in knitting. TRI 3011 and the shrinkage webcast handout both put stitch length and tightness at the centre of consistent shrinkage: maintain stitch length, knit a tightness factor as high as is practical, keep spreader and take-down tensions consistent, and choose a machine diameter that gives a good cut-and-sew width with low and balanced shrinkage.

Keep processing tensions down. TRI 3011 stresses overfeed, driven rolls and slack-loop control in inspection, extraction, slitting and tentering. The Q&A notes that wet, especially light, fabrics will stretch in length before they can turn undriven rollers.

Relaxation drying is described in TRI 3011 as one of the most significant advances towards shrinkage reduction for the finisher. A relaxation or belt dryer places wet fabric onto an open mesh belt in a relaxed form and dries it with forced hot air and tensionless mechanical action, for both open-width and tubular knits. Because there is no width restriction, width usually shrinks first, so some width adjustment, tensionless entry and controlled overfeed are needed afterwards.

Compacting compresses the course loops upon themselves. TRI 3011 describes two broad classes of machine: heated rolls and shoe units, or belt shrinking units. Both rely on a speed differential and a compaction zone; tubular and open-width systems are available. The fabric is steamed and then compacted, with heat and moisture helping to shorten the length stitches. Softener and moisture have a large effect on efficiency, and corrugation can come from over-compaction, uneven softener or the wrong moisture. CottonWorks records the resulting compactor creases when wrinkles on a folded tubular selvage are compressed into hard creases. The Q&A cautions that compaction generally will not remove much more than 50 per cent of the shrinkage present before the process, so it should not be the only means of control.

Sanforizing is, in that same Q&A, a trade name for compressive shrinkage, now often used to cover compaction in general. It is a physical process that forces the fabric to shrink upon itself; if it is done properly, the surface will not be changed. TRI 3011 notes that a Sanforize unit, normally used for wovens, can also be used as a compactor for knits. An endless elastic belt is stretched over rollers, the fabric is introduced between the belt and a usually steam-heated drum, and the belt is then allowed to shrink, compressing the fabric. The Q&A is clear about a limit: Sanforizing does not improve filling shrinkage on any fibre content.

Heat setting has to be stated carefully. As already noted, heat does not set cotton or shrink cotton fabric. For polyester, nylon and elastane the Q&A treats heat setting as a real process, but in a cotton–spandex blend it is only effective on the spandex and will not, by itself, stabilise the cotton structure. Times and temperatures are not given on the official pages used here, so none are quoted.

Anti-felting treatments are the wool route already described: Superwash-type shrink-resist treatments, including Hercosett, modify the scale surface so that wet agitation does not produce irreversible felting.

Chemical crosslinking, or resin finishing, is widely used on cotton, especially on open-width knits. TRI 3011 explains that crosslinking occurs through reactions of polyfunctional reactants with hydroxyl groups of adjacent cellulose chains. Benefits include wrinkle recovery, smoothness after laundering and dimensional stability; disadvantages include lower burst strength for knits, reduced abrasion resistance, possible shade change, reduced moisture regain, potential odours and sewing problems. Crosslinking can give low shrinkage without the increased bulk that compaction produces; see Easy-Care and Durable-Press Resins. Combinations of relaxation drying, compaction and crosslinking are, in ISP 1009, the way to get the most consistent residual shrinkage from lot to lot.

Self-made diagram for this article, after Cotton Incorporated TRI 3011 and ISP 1009, the CottonWorks Overcoming Shrinkage question-and-answer paper, and The Woolmark Company on anti-felting treatments.

Garment sizing and allowable shrinkage

There is no single standard shrinkage allowance for all cotton products. The CottonWorks Q&A says it is impossible to give a standard for all the sundry types of cotton products; what can be specified are the weight, cut-and-sew width and allowable shrinkage.

ISP 1009 notes that apparel processes often increase length shrinkage. The Q&A describes how spreading on a cutting table normally produces some gain in length and loss of width. Place as little linear tension as possible during spreading, and allow the stacked layers to relax for at least 8 hours, with 12 hours preferred, which also allows moisture regain for sewing. If fabric shrinkage is within tolerance but garment shrinkage is not, and the garment was sewn from the same tested lot, the Q&A points to stretching in cut-and-sew, or to markers that were not properly oversized.

The photograph below shows a historic pin tenter, a reminder that width has always been held during finishing. Modern open-width work still has to control width and overfeed; if tenter pins travel too far in from the selvage they can leave pin holes.

A historic pin tenter frame at Helmshore Mills, holding fabric by pins along the edges. Width has long been set this way during drying and finishing; pin holes become a defect when the pins venture too far in from the selvage. Photograph by Clem Rutter, Wikimedia Commons, CC BY 3.0. Cropped and resized to 800 pixels wide.

FAQ

Is shrinkage the same as dimensional change? Dimensional change is the broader term. It is a percentage of the initial dimensions, and it may be shrinkage or growth in length or in width. Report the two directions separately.

Why do knits usually shrink more than wovens? Knitted fabrics are inherently more prone to shrinkage than wovens, and a cotton knit is easily distorted by processing tensions, according to TRI 3011 and ISP 1009. Wovens are more stable, but they are often held to tighter shrinkage specifications.

Does tumble-dryer heat shrink cotton? Not according to Cotton Incorporated. The webcast states that heat does not shrink cotton fabrics, and that the tumble dryer shrinks cotton by stress-free mechanical action as the cloth dries. Excess heat may yellow cotton or stiffen the hand. Some synthetic fibres, including spandex, are sensitive to heat and can shrink.

Which standard should I cite on a test report? Name the preparation and measurement method, the wash and dry procedure, and the method used to determine the change. In the ISO system that is typically ISO 3759, a nominated procedure from ISO 6330, and ISO 5077. In the AATCC system, TM135 is for fabrics and TM150 is for garments.

Can compacting or Sanforizing alone meet a very tight residual-shrinkage target? Not always. The CottonWorks Q&A states that compaction generally will not remove much more than 50 per cent of the shrinkage present before the process, and that Sanforizing does not improve filling shrinkage on any fibre content.

Should I wash fabric before cutting? The Q&A says that relaxed washing and tumble drying is not practical for piece goods in a mill, because of cost and labour. In a plant, the equivalent steps are relaxation drying, compaction, a rest after spreading, and markers that allow for residual shrinkage.

Sources

• Cotton Incorporated, ISP 1009, A Guide to Improved Shrinkage Performance of Cotton Fabrics (2004): definitions of shrinkage, growth, construction and processing shrinkage, elastic shrinkage, drying shrinkage, swelling and deswelling, residual and reference (relaxed) dimensions, relaxation drying, compaction and crosslinking.
• Cotton Incorporated, TRI 3011, Wet Processing of 100% Cotton Knitted Fabrics (1999): knits versus wovens; knitting parameters; processing tensions; relaxation dryers; compaction, including use of a Sanforize unit; resin finishing.
• CottonWorks, Shrinkage and Skewing.
• CottonWorks / Cotton University, Overcoming Shrinkage webcast slides: dimensional change as a percentage of initial dimensions; delivered and reference states; “heat does not shrink cotton fabrics”; heat-sensitive synthetics such as spandex; three and five home-laundry tumble dries; specifications of weight, cut-and-sew width and allowable shrinkage.
• CottonWorks, Overcoming Shrinkage question-and-answer paper: length and width reported separately (5 × 5 per cent example); Sanforizing as a trade name for compressive shrinkage; compaction typically removing not much more than 50 per cent of prior shrinkage; Sanforizing and filling shrinkage; cotton not heat-settable like polyester; polyester, nylon and elastane as heat-settable; heat setting in cotton–spandex blends; no single standard allowance for all cotton products; spreading, rest times and oversized markers.
• CottonWorks, Corrective Action handout, Overcoming Shrinkage.
• The Woolmark Company, Machine Washable Wool: felting mechanism; Superwash; Hercosett.
• ISO 3759:2011 / EVS-EN ISO 3759:2011: preparation, marking and measuring of specimens (official abstracts).
• ISO 6330:2021 / EVS-EN ISO 6330:2021: domestic washing and drying procedures (official abstracts).
• ISO 5077:2007 / EVS-EN ISO 5077:2008: determination of dimensional change in washing and drying (official abstracts and EVS scope caution for deformable materials).
• AATCC TM135-2025, Dimensional Changes of Fabrics after Home Laundering (official store abstract).
• AATCC TM150-2025, Dimensional Changes of Garments after Home Laundering (official store abstract).

Common Knitting Faults and How to Fix Them

Holes, needle lines, barré and skew are everyday quality problems in weft knitting, on both circular and flat machines. The same fault can have more than one cause, so diagnosis starts with what the cloth looks like and then works back to the yarn, the needles and the settings.

ASTM D3990 is the ASTM terminology standard for defects in woven and knit fabrics. The official store page confirms that scope; it does not publish the individual definitions. The descriptions and remedies below come from Cotton Incorporated’s Defects Glossary on CottonWorks, and from the technical bulletins TRI 3015 (holes), TRI 1002 (barré) and TRI 2002 (skew, torque and spirality). TRI 2007, on machine setup, is written for circular machines. The published examples are mostly circular, though the same yarn, needle and tension checks apply on a flat-bed machine.

Yarn count, machine gauge and stitch length belong together when you judge whether a yarn is too coarse for the hook; see Yarn Count Systems Explained. Fabric mass is GSM. The structures in which these faults most often appear are compared in Single Jersey vs Rib vs Interlock. Start with direction: CottonWorks classifies many knit defects as vertical, wale-direction faults or as horizontal, course-direction faults. Isolated defects sit in one place; finishing defects may appear only after compaction, dyeing or tentering. For laboratory tests more generally, see Fabric Testing: Methods, Equipment and What Results Mean.

Self-made diagram for this article, after CottonWorks defect classifications and Cotton Incorporated TRI 1002 and TRI 2002. The groupings are a diagnostic aid, not a grading scale.

Holes

A hole is an opening where yarn has been broken, cut, or prevented from interlooping. CottonWorks records two knit examples: a lint ball interfering with interlooping in a double knit, and fabric “pulverised” during compaction in a single knit. TRI 3015 adds that holes are often first seen at garment inspection, so the cause may lie in knitting, later physical damage, or chemical damage during bleaching or finishing.

Yarn-related causes in TRI 3015 include a yarn too coarse for the gauge or hook; thick and thin places; yarn too weak for the tightness, tension and stitch length in use; twist so high that the yarn kinks; poor knots or splices, including long tails that double or triple the diameter; excessive hairiness; and high trash. If the stitch length is too short, the extra stress can make holes; if it is too long, drop stitches are more likely than holes. Machine causes include high yarn tension; a feeder timed too early or too late; a creel or path that rubs the end; take-down tension that is too high, or so low that previous loops ride up; worn or bent hooks, worn cams, and dials or cylinders out of centre; and incorrect sinker or cylinder-to-dial timing. After knitting, fabric can be snagged, over-spread, pinched in a compactor, or cut by sewing needles. Chemical damage includes over-activation of hydrogen peroxide by iron, over-processing, and over-crosslinking with resin.

Prevention follows the same list: match yarn count to gauge, reject serious thick or thin places, keep twist within the bulletin’s suggested ranges (a twist multiple of 3.2 to 3.8 for ring-spun cotton and 3.6 to 4.2 for open-end; higher twist can cause problems), tie knots correctly, keep the yarn path clear, and keep needle beds clean and properly lubricated. To examine a greige hole, look under magnification, count how many yarns are broken or separated, and decide whether a yarn looks cut or pulled apart. A hole on one wale points to that needle; more than one hole on the same wale is a reason to check the knitting elements.

Self-made diagram for this article, after the greige-hole examination sequence in Cotton Incorporated, TRI 3015, Guide to Evaluating and Reducing Holes in Knitted Fabrics.

Dropped stitches

CottonWorks defines dropped stitches, in double-knit examples, as stitches that fail to form because of a malfunctioning needle or jack. They are warp-line, vertical defects. They are not the same as a press-off, in which needles cease to function and the fabric falls off a circular machine or the design is destroyed.

TRI 3015 links drop stitches to thick and thin yarns, twist liveliness, poor knots or splices, and hairiness with lint build-up. Stitch length that is too long makes drop stitches more likely than holes. Yarn tension that is too low, or a feeder timed too early or too late, can leave the yarn badly positioned and produce either holes or drop stitches. The remedy is to replace or repair the needle or jack, clear wax and lint from guides, and correct stitch length, feeder timing and input tension. On patterned machines, treat random dropped stitches as a selection problem as well; that case is covered under tuck and miss faults below.

Needle lines and runs

CottonWorks defines a needle line, in a double-knit example, as the result of a bent needle. It is a vertical, wale-direction fault. A closely related defect is a run: a vertical line of unformed stitches from a broken needle or jack, shown on single-knit fabric and listed as a major defect. TRI 1002 adds that worn needles generally produce length-direction streaks, and that uneven cylinder-height needles can produce wavy barré, so a vertical line may also be a needle that is worn, badly seated, or of a different height from its neighbours.

Replace the damaged or worn needle, and check neighbouring needles, latches and tricks at the same time. A scheduled needle check during style changes, the subject of TRI 2007 for circular machines, stops one bad needle from marking a whole roll.

Barré and streaks

Cotton Incorporated, citing ASTM terminology in TRI 1002, defines barré as an unintentional, repetitive visual pattern of continuous bars and stripes, usually parallel to the filling of a woven fabric or to the courses of a circular-knit fabric. In a warp knit, barré normally runs in the length direction, following the yarn. A barré streak can be one course wide or several courses wide, a “shadow band”.

CottonWorks gives two weft-knit examples that produce a barré appearance: a coarse yarn at one feed, and a machine that continues to run with one yarn broken or missing. Both are weft-line, horizontal defects. A related appearance is a fine yarn or a loose course, which can look like fine width-wise cracks and can be hard to tell apart on the back of a single knit.

TRI 1002 sums up the causes in one word: inconsistency. In the fibre, that can be poor control of diameter or colour, or too high a coefficient of variation of micronaire in the laydown. In the yarn, it includes mixing counts, spinning systems, blend levels, suppliers, twist, hairiness or wax, and differences in mercerisation or conditioning. In knitting, the bulletin lists improper stitch length or tension at a feed, variation in fabric take-up, excessive lint, variation in oil content, worn or uneven-height needles, and a double feed end.

To investigate, examine both sides on a flat table, then view the cloth under fluorescent and ultraviolet light, which makes mineral oils easier to see. Record the frequency, direction, light or dark character, and repeat length of the streaks. An Atlas Streak Analyzer impression can help to separate physical streaks from dyeability differences. If the cause looks physical, compare twist and linear density in light and dark courses, and use microscopy to check for mixed spinning systems or mixed S and Z twist. Prevention is consistency: keep lots apart, and equalise stitch length and tension at every feed.

Self-made diagram for this article, after the visual and physical analysis sequence in Cotton Incorporated, TRI 1002, Barré. The three impression outcomes are those listed in the bulletin.

Spirality or skew

Cotton Incorporated’s TRI 2002 treats skew, torque, spirality, bias and shear distortion as names for the same phenomenon: knitted wales and courses angularly displaced from a right angle. If the wales lean from the vertical, the bulletin calls it wale skew; if the courses lean from the horizontal, it is course skew. The displacement can be expressed as a percentage or as an angle in degrees. A figure in that bulletin labels wale skew as the result of wale loop distortion.

Cotton single jersey is particularly prone to this when it is allowed to relax. Causes in TRI 2002 include yarn twist and twist liveliness, twist direction, the spinning system, stitch tightness, the number of feeders, the rotational direction of the knitting cylinder, and the finishing techniques used. In tubular goods, yarn-related skew often appears as wales spiralling around the tube while the courses stay closer to the horizontal. The bulletin’s practical conclusion is that the best answer is either plied yarns or alternating feeds of opposite twist. If singles yarns must be used, resin finishing is said to offer reasonable control. AATCC lists Test Method 179, Skew Change in Fabrics After Home Laundering; TRI 2002 includes it as an appendix. Official AATCC pages confirm the title, not the procedure.

Oil spots

CottonWorks describes oil spots as deposits of oil that have fallen onto the fabric from some processing step. They are typically round or tear-drop in shape, but they can be irregular.

TRI 1002 lists variation in oil content among the knitting-machine causes of barré, and notes that mineral oils glow under ultraviolet light. Streaks that glow under UV light suggest improper preparation, which can happen when a spinner or knitter changes the oil or wax without a matching change in scouring. TRI 3015 asks for proper lubrication of needle beds and knitting elements, which reduces fabric-forming stresses and wear, together with cleaning to avoid lint, grime and yarn wax. Lubricate the machine correctly, keep oil off the cloth, and make sure preparation can remove the oil and wax actually on the yarn.

Slubs and thick or thin yarn

CottonWorks defines a slub, on single-knit fabric, as a short, thick or heavy place in the yarn. It is an isolated defect. A different, width-wise appearance is a coarse yarn at one feed, already mentioned under barré, or a fine yarn that can resemble a loose course.

TRI 3015 treats thick and thin yarns as a cause of variable tension, holes and drop stitches, and tells the knitter not to use yarn with high imperfections, especially very thin or thick segments. Check yarn quality in the fabric and in inventory when holes look as if the yarn has been pulled apart at a thick or thin place. The remedy sits mainly in the yarn: clearer winding, agreed limits on slubs and thin places, and not mixing lots at the creel. A slub already knitted in has to be cut out or downgraded.

Tuck and miss faults

A tuck is not always a fault. In a piqué or other designed structure it is an intentional stitch, as explained in the jersey, rib and interlock article. It becomes a defect when it is unintentional.

CottonWorks defines unwanted tucking as the result of a malfunctioning needle. Tucking occurs when a needle retains one loop, takes on one or more additional loops, and then casts all of them together. A related single-knit defect, birdseye, is the result of erratic and unintentional tucking caused by a malfunctioning needle. A skip stitch, in a double-knit example, is the result of a stuck jack that fails to actuate the needle, so a stitch is skipped. When the yarn is picked up for the next stitch, a float is formed on the face of the fabric. Mis-selection is described as a pattern corrupted by the random dropping of stitches, which may be the result of sticking jacks or erratic yarn feed.

Replace or free the needle or jack, clear the tricks, and check that the intended cam or selection path is actually being followed. If the fault is isolated to one wale, start with that needle. If stitches are dropped at random across a pattern, look at jacks, selection and yarn feed together.

Pin holes and other small holes

In the CottonWorks glossary, pin holes are a finishing defect: holes resulting from running the fabric over a pin tenter, when the pins venture too far in from the selvage and distort or tear the fabric.

Small holes in knitted fabric are often something else, and they should not be assumed to be tenter pins without evidence. TRI 3015’s greige examination is the right way to tell a single-needle problem, a thick or thin yarn, a lint ball, or later mechanical damage from a pin-tenter mark near a selvage. Compactor damage, also listed by CottonWorks as a hole in single-knit fabric, is a finishing cause rather than a knitting one.

Loop distortion

TRI 2002 uses “wale loop distortion” for the lean of wales that produces wale skew, already discussed under spirality.

A different kind of loop movement appears in finishing. In Cotton Incorporated’s ISP 1009 shrinkage guide, corrugation or wrinkling of the surface because of improper loop movement during compaction is a known finishing defect. CottonWorks records compactor creases on single-knit fabric when wrinkles on a folded tubular selvage are compressed into hard creases. Those are not knitting faults, but they can be mistaken for them if greige cloth is not inspected first. Use plied yarns or alternating twist to limit spirality, avoid mixing S and Z lots, and set the compactor so that loops are compressed evenly.

A small circular weft-knitting machine, showing the cylinder of needles around which wales form. A bent or worn needle at one position is a typical starting point for a needle line or a run. Photograph by Mary Mark Ockerbloom, Science History Institute, Wikimedia Commons, CC BY-SA 3.0. Cropped and resized to 800 pixels wide.

A quick fault-finder

Confirm the direction of the fault, then test the most likely cause first. This table is a starting point, not a substitute for looking at the cloth.

What you see	First places to look	Typical correction
Isolated hole; yarn pulled apart	Thick or thin yarn, knot, splice, lint ball	Check yarn quality; clear lint; review tension and stitch length
Hole or holes on one wale	Bent, worn or damaged needle	Replace the needle; check neighbouring elements
Hole after finishing, near a crease or selvage	Compactor pinch or pin tenter	Reset the compactor or pin line; inspect greige cloth first
Vertical dropped stitches or a run	Needle or jack not knitting; stitch length too long; tension too low	Repair the element; correct stitch length, feeder timing and tension
Fine vertical line (needle line)	Bent or worn needle; uneven needle height	Replace and equalise needles
Horizontal bars or a shadow band (barré)	Mixed yarn lots; stitch length or tension at one feed; oil or wax	Segregate lots; equalise feeds; use UV if oil is suspected
Fine width-wise crack	Fine yarn or a loose course	Check that feed’s yarn and stitch cam
Wales leaning; garment twists after washing	Yarn torque; single jersey; finishing tension	Ply or alternate twist; relax without adding torque
Round or irregular oil mark	Oil from a processing step	Correct lubrication; improve preparation
Short thick lump (slub)	Yarn irregularity	Improve clearing; do not mix packages
Unwanted tuck, birdseye, float or broken pattern	Malfunctioning needle or stuck jack; erratic feed	Repair the element; check selection and yarn feed

FAQ

Is a hole always a knitting fault? No. TRI 3015 distinguishes knitting causes from later physical damage, such as snagging, over-spreading or compacting, and from chemical damage in bleaching or resin finishing. CottonWorks also records holes created by lint during knitting and by compaction.

How do I tell a needle line from a dropped-stitch run? A needle line, in the CottonWorks double-knit example, is the result of a bent needle and may be a relatively fine vertical mark. A run is a vertical line of unformed stitches from a broken needle or jack. Both follow a wale.

Why does barré sometimes appear only after dyeing? TRI 1002 states that barré can be caused by physical, optical or dye differences in the yarns, by geometric differences in the fabric, or by a combination. Dyeing can reveal a difference that was already present. Ultraviolet light can show mineral oil.

Do these faults occur on flat machines as well as circular ones? Yes, in principle. A bent needle, a thick place in the yarn, a bad knot, or a wrong yarn tension will mark a V-bed fabric as surely as a circular one. The published examples are mostly circular; apply the same checks on a flat machine.

Can I correct spirality in finishing alone? Finishing can relax the fabric and, if singles yarns must be used, TRI 2002 says resin finishing offers reasonable control of skew. The same bulletin still puts the best answer in the yarn: plied yarns or alternating feeds of opposite twist.

Sources

• ASTM D3990-12(2020), Standard Terminology Relating to Fabric Defects (official scope: defects in both woven and knit fabrics).
• CottonWorks Defects Glossary (Cotton Incorporated), including the individual entries Needle Line (0179), Run (0174), Dropped Stitches (0189), Hole (0183), Hole (0184), Slub (0182), Tucking (Unwanted) (0185), Birdseye (0178), Skip Stitch (0186), Mis-selection (0187), Coarse Yarn (0172), Missing Yarn (0173), Fine Yarn - Loose Course (0191), Press-off (0192), Oil Spot (0132), Pin Holes (0147) and Compactor Creases (0181).
• Cotton Incorporated, TRI 3015, Guide to Evaluating and Reducing Holes in Knitted Fabrics (2002).
• Cotton Incorporated, TRI 1002, Barré (1992).
• Cotton Incorporated, TRI 2002, Knit Fabrics and the Reduction of Torque (2001).
• Cotton Incorporated, TRI 2007, Weft Knitting Style Change-Over and Machine Setup Procedure (2004).
• Cotton Incorporated, ISP 1009, A Guide to Improved Shrinkage Performance of Cotton Fabrics (2004): compaction defects from improper loop movement.
• AATCC, Standard Test Methods and Procedures: listing for AATCC TM179, Skew Change in Fabrics After Home Laundering.

Single Jersey vs Rib vs Interlock: The Basic Weft Knits

Single jersey, 1 × 1 rib and interlock are the three weft-knit structures from which most everyday knitted cloth is built. They differ in how many needle beds are used, how those needles are arranged, and how the loops are intermeshed. Those differences decide whether a cut edge curls, how far the fabric will stretch in width, how stable it feels, and what it is used for.

This article compares the three structures as they are made on circular and flat weft-knitting machines. It is about fabric construction, not about choosing a yarn for a particular machine gauge; that is covered in Knitting Machine Gauge Explained. Yarn count, which affects fabric mass and tightness together with stitch length, is explained in Yarn Count Systems Explained. Fabric mass per unit area is GSM, and it cannot be read from the structure name alone.

The official vocabulary for industrially produced machine-knitted fabrics is EVS-EN ISO 8388:2003, the European adoption of ISO 8388:1998, also published as BS EN ISO 8388:2003. EVS-EN ISO 4921:2002 defines terms for basic knitting concepts. The descriptions below are taken from public technical pages that can be checked: Cotton Incorporated’s CottonWorks knitting courses, and the STARFISH fabric-type definitions published by Cotton Technology International.

Self-made diagram for this article, after the face and back descriptions in CottonWorks (Single & Double Knits; Knit Basics) and the STARFISH fabric-type definitions. The loops are stylised, not a standard notation.

Needle beds and gaiting

The first question is how many sets of needles the structure needs, and how those needles are placed relative to one another. CottonWorks calls this arrangement gaiting (also written gating).

Plain single jersey is made on one set of needles. In the STARFISH definitions, “single jersey” is a generic term for weft-knitted fabrics made on a single-jersey machine having one set of needles, and plain jersey is the simplest case: every course is made by one yarn knitting on all needles. On a circular machine those needles stand in tricks cut in a cylinder. CottonWorks’ machinery course notes that single-knit machines also have sinkers: narrow blades between adjacent needles that hold the fabric, assist loop formation, or allow a pile loop to be formed. A flat-bed machine with only one needle bed can also knit a jersey structure.

Rib and interlock need two needle beds. On a circular machine the second bed is a dial sitting above the cylinder, with tricks cut to the same gauge as the cylinder. On a flat machine the two beds are usually set in a V, which CottonWorks calls a V-bed; most flat-bed machines are described there as double-knit machines with two beds, used for heavier knits such as sweaters and for flat-knit trims such as polo collars.

The two beds can be gaited in two different ways, and that choice is what separates rib from interlock.

In rib gaiting, as CottonWorks describes it, the two sets of needles are not directly opposite each other. The cylinder needles sit between the dial needles, so both sets can knit at the same time without hitting. Face and back loops then alternate in the same course: cylinder needles make a face wale, dial needles a back wale. A 1 × 1 rib is completed on one yarn feed. STARFISH gives the same geometry in construction terms: rib fabrics are made with two sets of needles, one in the cylinder and the other in the dial, and the two sets are offset.

Self-made diagram for this article, after CottonWorks, Single & Double Knits (rib gaiting and interlock gaiting) and Knit Machinery (cylinder and dial; V-bed as a two-bed flat machine).

In interlock gaiting the needles stand directly opposite each other. To stop them colliding, opposing needles are not selected at the same time. CottonWorks notes that this arrangement needs two cam tracks on each bed and needles with long and short butts, set out alternately. At one feed, only half the needles knit (for example long-butt needles in odd cylinder and even dial positions); at the next feed the other half knit. Two feeds are therefore required to complete one visible interlock course, whereas a 1 × 1 rib is completed on one feed. STARFISH describes the same machine as having two sets of opposed needles, with alternate needles knitting and missing on dial and cylinder, and with the pattern repeating over two feeders.

Loop structure, face and back

CottonWorks’ Knit Basics is a clear starting point for reading a stitch. A horizontal row of loops is a course; a vertical column is a wale. A single jersey stitch has legs and a crown. The legs form a V, and the crown is more noticeable on the reverse side. On the technical face the stitches have an overall vertical appearance and you see mainly the legs; on the technical back they have an overall horizontal appearance and you see mainly the crowns. If every needle is fed a yarn and goes through the basic knitting cycle, and all the loops look alike, the fabric is single jersey.

A 1 × 1 rib looks the same on both sides. STARFISH defines a rib as a weft-knitted fabric in which both back and face loops occur along the course, but in which all the loops in any single wale are of the same type, either back or face. In 1 × 1 rib, single wales of face (plain) loops alternate with single wales of back (rib) loops. CottonWorks adds the practical detail that, in a relaxed fabric, the back wales hide behind the face wales. When the cloth is stretched in width the structure opens like an accordion and the back wales become visible.

Interlock has the appearance of a jersey face on both sides. STARFISH defines it as a weft-knitted, double-faced, rib-based fabric formed from two 1 × 1 rib fabrics joined by interlocking sinker loops. CottonWorks makes the same point: interlock is the interlocking of two 1 × 1 rib fabrics, and because the loops interlock and alternate from front to back, adjacent wales have little mobility. The wales on each side sit opposite each other.

Stretch, curling, running and stability

CottonWorks gives comparative stretch figures that should be treated as published descriptions, not as a substitute for a measured test. For jersey, extensibility in the width direction is approximately twice the length extensibility. For ribs, extensibility in the width direction stretches to twice that of a single jersey. That is why a basic rib is used where width stretch and recovery are wanted. CottonWorks also notes that a stretch yarn is sometimes added in the rib to help the fabric recover its shape. Interlock is described as more rigid and stable than a rib, because the interlocked wales cannot move in the same way.

Curling is a single-jersey problem. CottonWorks states that when jersey is cut across the width, the fabric curls and runs, and that, because of the horizontal knitting, it unravels from both ends. In the Knit Basics course, weft knitting is also characterised as having more horizontal stretch, and as a family of fabrics that curl, run and unravel. The more specific pages then distinguish the two-bed structures. A rib “does not curl if knit correctly but runs or unravels from the last knit.” Interlocks “are very stable fabrics with no curling.” Double-knit fabrics in general “tend to be more stable and curl less than single knits.”

A run is not the same as curl, and it is not the same as skew. Cotton Incorporated’s technical bulletin TRI 2002 deals with torque, also called skew or spirality: cotton single jersey knits tend to let the course and wale loops skew when the fabric is allowed to relax. An ideal single jersey would have courses and wales at a right angle, with the wales parallel to the edge of the tube or open-width piece. Skew is a finishing and yarn issue as well as a structural one; it should not be confused with the edge curl of a cut jersey panel.

On thickness and mass, only qualitative statements are used here. CottonWorks describes double-knit fabrics as heavier because they are composed of two fabrics linked together and therefore use more yarn, which also increases cost. Dial height on a circular double-knit machine is said to affect stitch length and, through it, weight, width, thickness, strength and hand. A tuck loop, which is the basis of piqué, is described as making the fabric wider, thicker and slightly less extensible. No typical GSM figures for jersey, rib or interlock are quoted in this article, because none of the cited official pages gives a verified range. If a specification needs a mass per unit area, measure it against a named method, as set out in the fabric GSM article.

Variants: 1 × 1 and 2 × 2 rib, piqué and double knits

STARFISH distinguishes 1 × 1 rib from 2 × 2 rib. In 2 × 2 rib, two wales of face loops alternate with two wales of back loops. That fabric can be made with two different needle set-outs. In so-called Swiss rib, one third of the needles in cylinder and dial are taken out of action in a 2/1 sequence (two knitting, one out); STARFISH notes that this is probably the most common set-out for 2 × 2 rib on rib machines, and that it is also often called 2/1 rib. In so-called English rib, half the needles are taken out in a 2/2 sequence (two knitting, two out). The needle set-out must be stated, because it changes how many needles are actually knitting.

Piqué is a single-jersey variant that uses tuck stitches, not a two-bed structure. CottonWorks explains that piqué takes its name from a pierced or open appearance: a visible micro-mesh of holes, commonly used in polo shirts and favoured for active apparel. Single piqué, which it says constitutes most of the piqué on the market, usually shows the technical face as the design face and repeats over four feeds: the first and third are plain jersey, and the second and fourth alternate knit and tuck, offset from one another. Double piqué also needs four feeds, is thicker than single piqué because two feeds are knitted on each needle before the loops are cleared, and usually uses the technical back as the selling face. A six-feed piqué is described as having more texture and stability than double piqué. STARFISH groups the same family of single-jersey tuck constructions under the name crosstuck, and notes that they are often called piqué or Lacoste.

“Double knit” in CottonWorks is the wider family of fabrics that use two needle beds. Interlocks, rib knits, Ponte di Roma and double-knit jacquards are listed as common examples, used for heavier garments that need structure or for layering. Ponte di Roma is described as a variation of interlock: the first two feeds knit interlock, the third knits jersey on the cylinder only, and the fourth knits jersey on the dial only, so four feeds make two visual courses. It has the same appearance on both sides, is thicker and more stable than interlock, and is used for tailored knit garments such as trousers and jackets.

Typical end uses, gauges and weight

End uses follow the properties. CottonWorks names jersey for t-shirts, underwear and swimwear, and notes that it comes in various weights depending on the use and is often used for garments worn close to the body. Ribs are used for dresses and sweaters, and as trim for neck collars, wristbands and waistbands; V-bed machines are used for chunkier or heavier-gauge ribs such as those on sweaters. Interlock knitted in combed cotton is described as very soft, with applications for dresses, baby clothes, and close-to-the-body garments such as turtlenecks. Piqué, as already noted, is the usual construction for polo shirts.

On machine gauge, CottonWorks’ circular-machinery page defines gauge as the number of tricks per linear inch on the cylinder. It states that standard knits are in the 20–44 gauge range, with ultra-fine knits reaching 60 gauge, and that for cotton 8–28 gauge is common, with finer gauges up to 44. Those figures are for circular machines in general, not a typical gauge for each of the three structures, and they should be read with the knitting-machine gauge article, which explains how gauge is defined on different machine types. This article does not invent a “usual” gauge for jersey, rib or interlock.

How to identify each fabric

Start with the two faces, then confirm with stretch and a close look at the wales.

Single jersey has a technical face of vertical V-shaped legs and a technical back of horizontal crowns. The two sides do not look the same. A cut edge tends to curl, and the fabric can be unravelled from both ends.

A 1 × 1 rib looks the same on front and back. In the relaxed cloth you see vertical face wales, with the reverse wales hidden in the grooves between them. Stretch the fabric in width: it opens like an accordion and the reverse wales appear. It should lie flat if it has been knitted correctly, and it unravels from the end knitted last rather than from both ends.

Interlock also looks the same on both sides, but each side resembles a jersey face rather than a rib. It feels more stable and does not curl. Because the wales on the two sides sit opposite each other, you cannot stretch the surface out to reveal a set of reverse-mesh wales in the way you can with a rib. CottonWorks notes a subtle rib structure on close inspection, but the fabric is the meshing of two 1 × 1 rib courses.

A rib knitted fabric, with vertical face wales and the reverse wales sitting in the grooves between them. Photograph by Hobbsansak, Wikimedia Commons, CC BY-SA 4.0. Resized to 800 pixels wide.

A counting glass, or pick glass, is the usual shop-floor way to see those wales and courses clearly. CottonWorks’ Knit Basics course points out that learning to find the crown and the legs is what leads to understanding stitch count and gauge. The British standard for this kind of work is BS 5441:1988+A1:2019, Methods of test for knitted fabrics, which covers weft-knitted fabrics, fabric construction analysis and visual inspection (the public catalogue page does not specify the aperture of the glass, so none is quoted here). Count what you can actually see, and name the structure from the arrangement of face and reverse wales, not from the garment type: a polo body may be piqué, and a T-shirt may have a rib collar.

Self-made diagram for this article. The comparisons are those published by CottonWorks and in the STARFISH fabric-type definitions. The stretch figures are CottonWorks descriptions, not laboratory measurements. No unsourced GSM ranges are included.

FAQ

What is the difference between rib and interlock? Both use two needle beds. In rib gaiting the needles are offset and can knit together, so a 1 × 1 rib is made on one feed and face and back wales alternate. In interlock gaiting the needles stand opposite each other and knit in an alternate sequence, so two feeds make one visible course and the fabric is two 1 × 1 ribs interlocked. Interlock is more stable and does not curl; rib has more width stretch.

Why does single jersey curl at the edges? CottonWorks states that when jersey is cut across the width it curls and runs. The two faces of the fabric are not the same, and the structure is made on one set of needles. Rib, if knitted correctly, and interlock do not curl in that way.

Does rib unravel? Yes. CottonWorks says a rib does not curl if it is knit correctly, but it runs or unravels from the last course knitted. Jersey unravels from both ends. Interlock is described as very stable, with little wale mobility, but a laboratory result should still be tied to a named method if the point is in dispute.

Is piqué a type of rib? No. Piqué, also often called Lacoste in the STARFISH descriptions, is a single-jersey construction that uses tuck stitches to give a micro-mesh surface. It is made on one needle bed. It is the usual fabric for a polo body; the collar and cuffs of the same garment are usually rib.

Can I tell the GSM from the structure name? No. Double knits are generally heavier than single knits because they use more yarn, but GSM still depends on the yarn count, the stitch length, the gauge and the finish. Measure mass per unit area by a named method, as explained in the GSM article. For laboratory fabric tests more generally, see Fabric Testing: Methods, Equipment and What Results Mean.

Can these structures be made on a V-bed machine as well as a circular machine? Yes. Rib and interlock need two needle beds, which may be a cylinder and dial or the two beds of a V-bed machine. CottonWorks notes that V-bed machines are used for chunkier or heavier-gauge ribs, such as those on sweaters, and that most flat-bed machines are double-knit machines with two beds.

Sources

• CottonWorks, Single & Double Knits (Cotton Incorporated): jersey, rib and interlock properties; rib gaiting and interlock gaiting; piqué; double knits and Ponte di Roma; end uses.
• CottonWorks, Knit Basics: courses and wales; legs and crowns; technical face and back; tuck stitches and piqué; weft-knit stretch, curling and unravelling.
• CottonWorks, Knit Machinery: Flat, Circular, and Seamless: cylinder, dial and V-bed; sinkers; circular gauge as tricks per inch, with the published circular-machine ranges; dial height and fabric weight.
• Cotton Technology International, STARFISH Model Environment, Fabric Types (2019): definitions of plain single jersey, rib, 1 × 1 and 2 × 2 rib (including Swiss and English set-outs), interlock, and crosstuck constructions often called piqué or Lacoste.
• EVS-EN ISO 8388:2003 / BS EN ISO 8388:2003 (official scope: terms for industrially produced machine-knitted fabrics).
• EVS-EN ISO 4921:2002 (official scope: terms for basic knitting concepts).
• BS 5441:1988+A1:2019, Methods of test for knitted fabrics (weft-knitted fabrics, fabric construction analysis, visual inspection; published 30 September 2019).
• Cotton Incorporated, TRI 2002, Knit Fabrics and the Reduction of Torque: skew or torque in cotton single jersey.

Yarn Count Systems Explained: Ne, Nm, Tex and Denier

Yarn count is the number that tells you how coarse or fine a yarn is. Mills and laboratories use several systems: tex and decitex, denier, metric count (Nm) and English cotton count (Ne). This article explains what those systems mean, how to convert between them with published factors, how plied yarns are described, and how linear density is measured by the skein method.

Yarn count is not fabric weight: fabric mass per unit area is GSM, grams per square metre, and you cannot read GSM from count alone. It is also not knitting-machine gauge. How a count is chosen for a needle bed is covered in Knitting Machine Gauge Explained.

Self-made diagram for this article. Definitions follow Coats, Thread Numbering (Bulletin 05), and AMANN, Textile numbering systems.

Direct and indirect systems

All common numbering systems relate a mass to a length. They fall into two families.

Direct systems express linear density: the mass of a stated length. Tex, decitex (dtex) and denier belong here. In a direct system a larger number means a coarser, heavier yarn. Coats, in its Thread Numbering bulletin, groups these as fixed-length systems, because a unit length is taken as fixed and the mass of that length is measured.

Indirect systems express a count: the length of a stated mass. Metric count (Nm) and English cotton count (Ne) belong here. In an indirect system a larger number means a finer yarn. Coats groups these as fixed-weight systems, because a unit mass is taken as fixed and the length of that mass is measured.

The words “fixed length” and “fixed weight” are not used consistently everywhere in the trade. AMANN describes the same two families and the same finer/coarser rules, yet it applies those labels the other way round. When a document says only “fixed-length system”, read the definition, not just the heading. The reliable distinction is direct (mass per unit length) versus indirect (length per unit mass).

What the main systems mean

The international reference for the Tex System is ISO 1144:2016. The official scope, as given in the EVS catalogue, is that the standard gives the principles and recommended units of the Tex System, includes conversion tables for calculating the tex values of numbers or counts in other systems, and states a procedure for implementing the system in trade and industry. It applies to all kinds of textile fibres, intermediate products (for example tops, slivers and rovings), yarns and similar structures. EVS records the second edition as valid from 14 September 2016.

The unit definitions below are those published by Coats and, where the wording helps, by AMANN. They agree with each other and with the SI equivalents tabulated by NIST.

Tex is the mass in grams of 1,000 metres of yarn. AMANN’s example is that 10 tex means 1,000 metres of the sample weigh 10 grams. The NIST Guide to the SI, Appendix B.8 lists the exact conversion 1 tex = 1.0 × 10⁻⁶ kilogram per metre, which is the same relationship.

Decitex (dtex) is the mass in grams of 10,000 metres, so dtex is ten times tex for the same yarn: 20 tex is 200 dtex. Filament yarns are often written in dtex.

Denier is the mass in grams of 9,000 metres. NIST tabulates 1 denier = 1.111 111 × 10⁻⁷ kilogram per metre, which is one-ninth of the tex factor, so denier = 9 × tex. Denier remains familiar for filament yarns and for some consumer products.

Metric count (Nm) is the number of hanks of 1,000 metres in one kilogram, which is the same as the length in metres of one gram. AMANN’s example is that Nm 10 means 1 gram of the sample is 10 metres long. A higher Nm is a finer yarn.

English cotton count (Ne), also written Nec or Ne B, is the number of hanks of 840 yards in one pound. Coats’ example is that Ne 1 means one pound contains 840 yards, and Ne 5 means it contains 4,200 yards (840 × 5). A higher Ne is a finer yarn.

ISO 2947:1973 is a changeover document rather than a set of exact factors: its official scope is to facilitate the move from traditional numbering systems to tex by providing recommended rounded tex values to replace yarn numbers in the six main traditional systems. ASTM D2260-24 is the current ASTM collection of conversion factors and equivalent yarn numbers; its official scope states that its content is basically consistent with ISO 2947. Use the edition named in a specification. The worked table later in this article is calculated from freely published Coats factors, not copied from those paid standards. This article does not quote hank lengths for worsted, woollen or linen lea counts, because the cited public pages do not state them.

Converting between systems

Coats publishes the following conversion relationships. They are the factors used for every worked number in this article.

• tex = 1,000 / Nm
• tex = 590.54 / Ne
• tex = denier / 9
• tex = dtex / 10
• dtex = 10 × tex
• denier = 9 × tex
• Nm = 1,000 / tex
• Ne = 590.54 / tex
• Nm = Ne × 1.6934
• Ne = Nm × 0.5905

AMANN publishes the same relationships with more heavily rounded constants (590 and 0.59). For a specification or a laboratory conversion, prefer the more precise Coats factors, or the official tables in ISO 1144 or ASTM D2260 when those documents are named in the order.

The constant 590.54 follows from the definition of cotton count together with official SI factors. Coats defines Ne as the number of 840 yard hanks per pound. NIST lists 1 yard = 9.144 × 10⁻¹ metre (0.9144 m; factors in boldface in Appendix B.8 are exact) and 1 pound (avoirdupois) = 4.535 924 × 10⁻¹ kilogram (0.4535924 kg). Then, as arithmetic:

840 × 0.9144 = 768.096 metres

0.4535924 × 1,000 = 453.5924 grams

tex of Ne 1 = 453.5924 / 768.096 × 1,000 = 590.541, which rounds to the Coats factor 590.54.

Worked conversions (arithmetic)

These examples use the Coats factors, rounded as stated. They are not measured yarns.

Example 1. Convert 30 tex to cotton count. Ne = 590.54 / 30 = 19.6846..., which is 19.68 Ne at two decimal places.

Example 2. Convert 40 Nm to tex. tex = 1,000 / 40 = 25 tex exactly.

Example 3. Convert 150 denier to tex. tex = 150 / 9 = 16.666..., which is 16.67 tex at two decimal places. The same yarn is 166.7 dtex (10 × 16.67).

Example 4. Convert 20 Ne to metric count. Going through tex keeps the rounding consistent: tex = 590.54 / 20 = 29.527 tex, then Nm = 1,000 / 29.527 = 33.867..., which is 33.87 Nm at two decimal places. Coats’ direct factor Nm = Ne × 1.6934 gives 20 × 1.6934 = 33.868, which rounds to the same two-decimal figure.

Self-made diagram for this article. Table values are arithmetic from the conversion factors published by Coats, Thread Numbering (Bulletin 05), rounded to two decimal places where the value is not a whole number. They are not measured yarns.

The table in the diagram is calculated from the same factors, starting from the tex column: Nm = 1,000 / tex, Ne = 590.54 / tex, dtex = 10 × tex and denier = 9 × tex, with Nm and Ne rounded to two decimal places where the value is not a whole number. The rows are rounded conversions, not a list of commercial products.

Ply notation and resultant count

A folded or plied yarn is made from more than one single. The number that matters for most specifications is the resultant count of the finished thread. Coats gives two rules:

• In fixed-weight (indirect) systems: resultant size = individual yarn count / number of plies.
• In fixed-length (direct) systems: resultant size = individual yarn count × number of plies.

A particular resultant size can be made with any number of plies.

Example 5 (arithmetic). Two plies, each of Nm 30 singles, have a resultant metric count of 30 / 2 = 15 Nm.

Example 6 (arithmetic). Two plies, each of 20 tex singles, have a resultant linear density of 20 × 2 = 40 tex. The same yarn is 400 dtex.

Those calculations assume that folding does not add or remove mass other than the second ply. Twist, a binder or finish can move a measured result slightly; the measured resultant, by a named method, is then the number to report.

Written shorthand such as 2/30 Nm, 30/2 Nm or 30/1 Ne is common, but it is not a single universal code. In some cotton-spinning documents the first number is the singles count and the figure after the stroke is the number of plies (30/1 for a singles 30 Ne yarn; 30/2 for two plies of 30 Ne, resultant 15 Ne). In some metric knitting documents the number of plies is written first (2/30 Nm for two plies of Nm 30, resultant 15 Nm). The two forms can be read as opposites if the convention is not stated. Write the singles count, the number of plies and the system in words, then give the resultant by the Coats rule.

ISO 1139:2025, also published as BS ISO 1139:2025 on 31 December 2025, specifies two methods of indicating the composition of single, folded, cabled or multiple-wound yarns. The official notation comprises linear density in the Tex System, the number of filaments in filament yarns, the direction and amount of twist, and the number of folds. It is not applicable to some special yarns, including fancy, textured or bulked yarns and yarns produced by wrapping a material round a core. Where a specification calls for ISO 1139, follow that standard rather than an informal stroke notation.

Sewing-thread ticket numbers are a further commercial shorthand. Coats notes that a ticket number is the manufacturer’s reference for the size of a given thread, that a higher ticket number is a finer thread, and that a Ticket 40 in one thread type is not the same as a Ticket 40 in another.

Self-made diagram for this article. The two resultant rules are those published by Coats, Thread Numbering (Bulletin 05). The worked numbers are arithmetic illustrations. Written forms such as 2/30 Nm or 30/2 Nm vary in trade; state the singles count, the number of plies and the system.

Count, diameter and fabric weight

Linear density is not yarn diameter. Two yarns can share a tex value and still differ in diameter if the fibre density, the twist or the bulk is different. This article does not give a diameter formula, because none of the cited public pages states one.

Nor is yarn count a fabric GSM. GSM is mass per unit area of the cloth, measured on a known area by a named method, as explained in the fabric GSM article. To go from yarn linear density to fabric mass you also need the construction, and after dyeing and finishing you need a measurement. Garment merchandisers who put a count on an order should name the system, the resultant of any ply, and, where fabric weight is also specified, a GSM method and fabric state.

Measuring count: the skein method

Count on a package label is a nominal figure. When the number must be checked, the usual laboratory method is to reel a known length into a skein, weigh it, and express the result in the required numbering system. ASTM D1907 notes that the same skeins may also be used later for skein breaking strength.

A laboratory wrap reel used to wind a known length of yarn into a skein before weighing, which is the principle of the skein method in ISO 2060 and ASTM D1907. Photograph by Ikiwaner, Wikimedia Commons, CC BY-SA 3.0. Cropped and resized to 800 pixels wide.

Two current methods cover this work. They are related, but they are not interchangeable on every yarn.

ISO 2060:1994 specifies a method for the linear density of all types of yarn in package form. The official abstract states that it includes seven optional procedures based on different methods of conditioning and preparation; that it applies to single, folded and cabled yarns; that it is not applicable to yarns which stretch more than 0.5 per cent when the tension, in centinewtons per tex, increases from 0.5 to 1.0; and that it is not applicable above 2,000 tex. EVS records the standard as valid from 17 November 1994.

ASTM D1907/D1907M-12(2025) is the current ASTM skein method (the store lists the 12R25 edition as active). Its official scope covers yarn in package form, with provision for expressing the result in all the traditional numbering systems. It applies to yarns that stretch less than 5 per cent when tension increases from 0.25 cN/tex to 0.75 cN/tex; by agreement, and with a lower reeling tension, it may be adapted to yarns that stretch more than 5 per cent. It applies to yarns finer than 2,000 tex, and may be adapted to coarser yarns with shorter skeins and alternate reeling conditions agreed by the parties.

The stretch limits are not the same (0.5 per cent under one tension pair in ISO 2060; 5 per cent under a different pair in ASTM D1907). A result from one method should not be treated as a result from the other without agreement.

ASTM D1907 sets out seven options, depending on whether the yarn is scoured, whether it is weighed conditioned or oven-dry, and whether commercial moisture regain or a commercial allowance is added. Option 1 (unscoured, conditioned yarn) is generally used for yarns spun on the cotton system. Options 6 and 7 (scoured, oven-dried yarn, plus commercial moisture regain or allowance) are generally used for filament yarns, or yarns containing wool fibres. The parties must agree the option, or follow the one prescribed in the relevant method or tolerance. ISO 2060 likewise has seven optional procedures, based on different methods of conditioning and preparation.

Moisture and finish change the mass of a skein, just as they change a fabric GSM. Always report the method, the option or procedure, and the state of the yarn. For laboratory fabric tests more generally, see Fabric Testing: Methods, Equipment and What Results Mean.

FAQ

What is the difference between tex and Nm? Tex is a direct system: grams per 1,000 metres. Nm is an indirect system: metres per gram, or 1,000 metre hanks per kilogram. They are exact reciprocals: tex = 1,000 / Nm, and a higher tex is coarser while a higher Nm is finer.

How do I convert Ne to tex? Use tex = 590.54 / Ne, the factor published by Coats. For 30 tex that is 19.68 Ne at two decimal places (590.54 / 30, arithmetic). For an official table, use ISO 1144 or ASTM D2260 as named in the specification.

Is denier the same as dtex? No. Denier is grams per 9,000 metres; dtex is grams per 10,000 metres. For the same yarn, denier = 0.9 × dtex, or denier = 9 × tex. A 150 denier yarn is 16.67 tex, or 166.7 dtex, at the rounding used above.

What does 2/30 Nm or 30/1 Ne mean? Treat these as trade shorthand, not as a single international code. Confirm whether the first figure is the number of plies or the singles count, then apply the Coats rule: divide in Nm or Ne, multiply in tex or denier. Two plies of Nm 30 singles have a resultant of 15 Nm. If a specification requires a standardised designation, use ISO 1139 in the Tex System.

Can I calculate fabric GSM from yarn count? No. Count is mass per unit length of the yarn. GSM is mass per unit area of the fabric. You need the construction as well, and after finishing you need a measurement against a named fabric method. See the fabric GSM article.

Which method should a laboratory use to measure yarn count? Name the method in the specification. ISO 2060 and ASTM D1907 are both skein methods for yarn in package form, but they have different stretch limits and their conditioning options must be agreed. Report the option, not only the number.

Does a higher count always mean a finer yarn? Only in indirect systems (Nm, Ne). In direct systems (tex, dtex, denier) a higher number is coarser. Always name the system.

Sources

• ISO 1144:2016 (EVS catalogue; official scope: principles and recommended units of the Tex System, conversion tables, implementation procedure; fibres, intermediates, yarns; valid from 14 September 2016).
• ISO 2947:1973 (EVS catalogue; official scope: recommended rounded tex values to replace traditional yarn numbers in the six main systems).
• ASTM D2260-24 (official scope: conversion factors and equivalent yarn numbers; content basically consistent with ISO 2947; current edition).
• ISO 2060:1994 (EVS catalogue; official abstract: skein method, package-form yarns, seven optional procedures, stretch and 2,000 tex limits).
• ASTM D1907/D1907M-12(2025) (official scope and significance: skein method, traditional numbering systems, 5 per cent stretch limit, 2,000 tex, seven options).
• ISO 1139:2025 and BS ISO 1139:2025 (official scope: designation of single, folded, cabled or multiple-wound yarns in the Tex System; published 31 December 2025 as the British adoption).
• Coats, Thread Numbering (Bulletin 05) (definitions, conversion factors including 590.54, resultant-count rules, ticket numbers).
• AMANN, Textile numbering systems (tex, dtex, denier, Nm and Ne B definitions; conversion formulae with rounded constants).
• NIST Guide to the SI, Appendix B.8 (1 tex = 1.0 × 10⁻⁶ kg/m; 1 denier = 1.111 111 × 10⁻⁷ kg/m; 1 yard = 9.144 × 10⁻¹ m, exact where boldface; 1 pound avoirdupois = 4.535 924 × 10⁻¹ kg).