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.
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.
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 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.
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.
