Interlock vs single jersey: which knit for your garment?

Single jersey is knitted on one set of needles: it is light, drapey, quick to make and usually the cheapest knit per square metre, but its cut edges curl and it can twist after washing. Interlock is knitted on two sets of needles as two 1x1 ribs locked together: it looks the same on both faces, is heavier, thicker and more stable, does not curl, and costs more. Jersey is the default for t-shirts. Interlock earns its price in babywear, smooth premium basics, printed garments and opaque activewear.

What is the structural difference?

Single jersey is the simplest weft knit. Every needle knits every course, and every loop is pulled through to the same side. That gives a face of neat vertical “V” columns and a back of horizontal loop heads, so the two sides look different. On a circular knitting machine it uses a single set of needles, the cylinder.

Interlock is a double knit. Cotton Incorporated explains the name: it is two 1x1 rib fabrics “interlocked” into one. The machine has two needle beds, the cylinder and the dial, with their needles set directly opposite each other, in what is called interlock gaiting. Because opposite needles would collide, they never knit at the same time: on one feed, alternate needles on each bed knit; on the next feed, the others do. It therefore takes two feeds to build one visible course, where jersey takes one. The result looks like fine jersey on both sides, with a faint rib visible on close inspection.

Wool education notes from the University of New England summarise interlock as thicker and heavier than rib of the same gauge, the same on both sides, with good width stretch and recovery, and a stable, balanced structure.

Why does single jersey curl, and interlock not?

Jersey curls because yarn bent into loops stores energy and tries to straighten. Since every loop in jersey faces the same way, that energy is unbalanced, and cut edges roll. The IIT knitting notes on India’s NPTEL platform identify stored bending energy as the primary cause, and add that yarn with more twist resists bending more, stores more energy, and so curls more.

In interlock, and in rib, loops meshed in opposite directions cancel each other’s pull. The University of New England notes are explicit that, like all rib structures, interlock does not curl at the edges and is easy to handle in cutting.

This is the whole story behind searches for “anti-curling interlock fabric”. Interlock is anti-curl by construction; it does not need a special finish to lie flat. Curl in jersey matters mainly in the cutting room and at the sewing machine, where rolled edges slow spreading and make seams harder to guide, and on raw-edge designs, where the roll is part of the look.

What about twisting and spirality?

Single jersey has a second weakness: spirality, where the wales run on a slant rather than straight down, and side seams twist around the body after washing. The University of New England notes attribute it to singles yarns, or unbalanced two-fold yarns, knitted into single-bed structures. The NPTEL notes state that a rib construction does not show spirality of the wale line. Interlock, built from two ribs, shares that balance.

Jersey can be made stable, with the right yarn twist, fabric finishing and cutting, and most good tees are. But if a design cannot tolerate any twist, such as a garment with prominent vertical stripes or side panels that must stay straight, interlock removes one source of risk.

Interlock vs single jersey at a glance

The comparisons below assume the same yarn and the same loop length. The rankings for weight, thickness and stretch are from the NPTEL knitting notes, which rank the basic weft knits against each other on exactly that basis.

Weight, handle and opacity

Because interlock is two layers of loops knitted as one, it carries more yarn in every square metre. That makes it heavier and fuller than jersey knitted from the same yarn, with better cover, which matters in pale colours and in leggings. The University of New England notes describe interlock as having an extremely soft handle, a high degree of firmness and good moisture absorption. Cotton Incorporated adds that interlock knitted in combed cotton can be very soft, which is why it appears in dresses, baby clothes and close-to-the-body garments such as turtlenecks.

Handle is also where the two differ most in wear. Jersey drapes and clings; interlock holds a little more shape and feels fuller in the hand. Neither is better. A relaxed, fluid tee wants jersey. A structured baby sleepsuit or a smooth, substantial long-sleeve top may want interlock. Our fabric and GSM guide for knitwear explains how weight and yarn change handle within each construction, so compare the two knits at similar finished weights before deciding.

Which is better for printing?

Interlock’s two smooth faces and its stability make it a forgiving print base. It does not curl on the print table, it tends to stay put under the screen, and a large area print is less likely to distort as the garment is worn. Our kidswear page notes interlock at 200 to 240 GSM for sleepsuits and anything printed for that reason.

Single jersey prints perfectly well and is the usual base for printed tees. It asks for a little more care: fabric needs to be laid flat without stretching, and a heavy plastisol or large solid print on a light jersey can feel stiff and change how the fabric drapes. Our screen printing page covers ink choices for both.

What makes interlock cost more?

Several things push the price of interlock above jersey, and they compound:

• More yarn per square metre. Cotton Incorporated notes that double knits use more yarn, which increases the cost of the fabric.
• Finer yarn at the same machine gauge. Cotton Incorporated’s knitting guidance suggests yarn counts by gauge. On a 24 gauge machine it suggests Ne 24 to 36 for jersey but Ne 32 to 48 for interlock; on a 28 gauge, Ne 30 to 45 for jersey and Ne 40 to 60 for interlock. Higher Ne means finer yarn, and the University of New England notes that as yarn gets finer, its cost rises.
• Slower knitting per course. Two feeds make one visible course, where jersey needs one.

Against that, interlock can save time in cutting and sewing because it lies flat, and it can reduce returns for twisting. For most adult t-shirts, jersey still wins on price and drape.

Which knit suits which garment?

• T-shirts: single jersey in almost every case. Interlock tees exist at the premium end, for a smooth, substantial feel. See our t-shirt manufacturing page.
• Babywear and kidswear: interlock is a favourite for sleepsuits, bodysuits and printed pieces, because it is soft, opaque and stable. Combed cotton jersey is used for lighter pieces. Our kidswear page covers both.
• Polo shirts: piqué is the classic polo fabric. Interlock gives a smoother polo face, in cotton or in polyester blends for performance styles. Our polo shirt page covers the choice.
• Activewear and leggings: polyester and polyester-elastane interlock is common for training tops, and interlock gives a heavier, more opaque legging. See our activewear page.
• Dresses: jersey for drape; interlock where a smoother face and more body are wanted.

Double knits beyond interlock

Interlock is one member of the double-knit family, all made on two needle beds. Rib is the simplest, used for trims and fitted tops. Ponte di Roma is an interlock variation that knits one interlock course and then a course of jersey on each bed separately; Cotton Incorporated describes it as thicker and more stable than interlock, with a slight horizontal rib, used for tailored knit trousers and jackets. Double-knit jacquards hide unused colours as a second knitted layer rather than floats. If interlock is not quite heavy or stable enough for a structured design, ponte is usually the next fabric to look at.

Shrinkage and testing for both knits

Neither construction is immune to shrinkage. Cotton Incorporated’s guidance on shrinkage and skewing notes that knitted fabrics of all constructions are inherently more prone to shrinkage than wovens, and that the result depends on knitting parameters, the tension the fabric sees in processing, and the relaxation and compaction used in finishing. Interlock’s stability helps with twist, not automatically with length shrinkage. So test both the same way: dimensional change after washing, and for jersey, twist after washing as well. Set your limits in the tech pack before the fabric is knitted, not after the first samples come back.

Buying anti-curl interlock for a garment order

Requests for anti-curling interlock often come with a fibre, a stretch level or a custom colour attached. Each is a line in the fabric specification, not a different product, because plain interlock lies flat by construction. Cotton Incorporated’s general rule for the family is that double knits tend to be more stable and curl less than single knits.

• Double-knit. Interlock is a double knit by definition, so “double-knit anti-curl interlock” describes ordinary interlock. For more weight and stability, see ponte di Roma above.
• Cotton or a cotton blend. State every fibre and its percentage. Interlock takes finer yarn than jersey on the same machine, as the cost section above explains.
• Stretch. Interlock already has good stretch and recovery across the width. If the garment needs more, write the elastane percentage into the specification and ask for a stretch and growth result to a named method rather than accepting “high-stretch” as a description. ASTM D2594 is written for knits that stretch a lot and recover well under low tension; fabrics meant for support are better tested by other methods.
• Custom colour. Give a physical colour standard, approve a lab dip on the actual interlock, and expect a minimum per colour from the dye house. Our guide to sourcing fabric for a clothing line explains why fabric minimums are set per colour. For dark or bright shades, ask for colour fastness results on the bulk lot.

We do not sell interlock by the metre. We source it to your specification for garments made in our own knitwear factory, our sister company’s, from 500 pieces per style and colour, and test the bulk fabric against the approved swatch before cutting.

How to specify it, and what to do next

Write the construction by name, “100% combed cotton interlock” or “single jersey”, followed by the finished GSM with a tolerance, the yarn count if you know it, the colour and the tests. For jersey, add a spirality or twist limit and ask for it to be checked after washing. Then compare real swatches: jersey and interlock at similar weights look closer on screen than they feel in the hand.

If you are choosing between the two for a specific product, send us the garment type and target weight through the quote request form. Ask for knit-downs of both so you can feel the difference and see how each takes your print before sampling.