Two rolls sit on the cutting table. Both are 100% cotton, both are tubular, both are within ten grams per square metre of each other on the header card. One is single jersey, one is interlock. The hand feel is close, the colour is the same, and the quotes differ by a few cents per piece. On a 300-piece test order that difference looks like noise. On the sewing floor it decides whether the neckline recovers after stretching, whether the side seam spirals after the first wash, and whether the print sits on a surface flat enough to hold a fine half-tone.
Jersey and interlock are the two most common weft knits in apparel and are routinely treated as interchangeable in sourcing conversations. They are not: they are built on different machines, behave differently under tension, cost differently to knit and fail in different ways. What follows is written from the knitting and cutting side of a Bangladesh factory, in terms you can put into a tech pack and a fabric approval sheet.
What Single Jersey Actually Is
Single jersey is knitted on a machine with one set of needles, one needle bed, one cylinder. Every course of loops is drawn through the loops of the previous course on the same side, which produces two different faces on the same fabric. The technical face — the side that shows the vertical wales — is smooth. The technical back is a mesh of semicircular loops, the purl side, which is why jersey looks different inside and out.
That single-needle structure has three consequences you can see on the table at once.
Single jersey knits fast: each revolution lays one course at every feeder, so a 30-inch machine with 96 feeders at 25–30 rpm produces metres per minute — which is why jersey is the cheapest weft knit per kilogram. Spiral (torsion) is its known weakness: the loops lean slightly, so a tubular body can twist after washing unless the fabric is compacted or the panel is cut with a compensated side seam.
What Interlock Knit Fabric Is
Interlock is knitted on a machine with two sets of needles working at right angles — a cylinder and a dial — with two sets of needles facing each other. Each course is actually two interlocked 1x1 rib courses, one knitted on the cylinder needles and one on the dial needles, and each set of needles knits through the loops held by the other. The result is a fabric with two smooth, identical faces made of face loops, with the reverse loops buried in the middle of the structure.
That is the whole reason buyers specify interlock: it looks the same on both sides, and it does not curl. Because the two loop systems lock each other, the fabric is balanced, denser, and far more dimensionally stable than jersey.
Interlock also consumes more yarn per square metre, because the structure is denser and the stitch length shorter. That double hit — slower machine plus more yarn — explains most of the price gap.
Jersey vs Interlock vs Rib: Side-by-Side
Rib is included because most knit programmes use all three, and the confusion between interlock and 2x2 rib is common. They look similar in a folded swatch and behave very differently.
| Property | Single jersey | Interlock | 1x1 / 2x2 rib |
|---|---|---|---|
| Needle configuration | One bed (cylinder) | Two beds (cylinder + dial) | Two beds, needles selected in a rib pattern |
| Faces | Different face and back | Two identical smooth faces | Both sides ribbed, deeply textured |
| Typical GSM | 120–220 | 180–320 | 180–320 for body rib, 300–450 for cuff rib |
| Widthwise stretch | High, 40–60% | Moderate, 25–40% | Very high, 60–100% |
| Recovery | Moderate, prone to growth | Good | Excellent, snaps back |
| Edge curling | Strong | Minimal | Minimal |
| Spiral / torsion | Noticeable | Low | Low |
| Hand feel | Light, soft, dry | Denser, smoother, slightly cooler | Chunky, elastic, textured |
| Relative knit cost per kg | Lowest | 15–30% higher than jersey | Similar to interlock |
| Typical use | T-shirt bodies, singlets, linings | Polo bodies, babywear, dresses, matching sets | Cuffs, collars, waistbands, fitted bodies |
The column that decides most projects is the last one. If the fabric has to hold a shape at a cuff or waistband, rib is doing a mechanical job that jersey cannot do and interlock does only partially. If the fabric has to be flat, opaque and printable on both sides, interlock wins. If the fabric has to be cheap, light and drapey, jersey wins and you design around its weaknesses.
The Real Differences That Change a Garment
Stretch direction and growth
Jersey extends far in the width and recovers slowly. A jersey t-shirt body that is cut exactly to the spec measurement will often measure 1–2 cm wider after a wash cycle and a day on a hanger. Interlock moves less, so the spec holds. For a fitted women's top or a children's garment where the pattern is graded tight, this single property usually settles the choice before cost is discussed.
Spirality
Jersey spirals. The loops lean, the tube twists, and after washing the side seam of a jersey tee can shift several centimetres at the hem. Factories manage this by knitting with a balanced stitch length, compacting or calendering the fabric, and by cutting side seams with a counter-twist allowance. Interlock spirals very little because the two needle sets oppose each other. On striped jersey, spirality is visible as a diagonal drift in the stripe; that is a fabric approval issue, not a sewing fault, and it should be caught on the swatch.
Curling at the cut edge
Jersey curls at the cut edge and will not lie flat on the cutting table without a vacuum table holding it, and it curls again at the seam allowance inside the garment. Interlock lies flat. On a lightweight jersey, this is why bindings, tapes and overlocked edges are so common; on interlock you have the option of a clean, flat-felled or simple turned hem.
Opacity and cover
At equal GSM, jersey is more translucent because the structure is more open. White jersey under 160 GSM is close to transparent in daylight. Interlock at 200 GSM reads opaque in white because the two loop systems stack cover. If the design is a white or pastel jersey body, the fabric either moves up in weight or accepts a higher yarn count and tighter stitch length — both of which narrow the gap to interlock pricing.
Print surface
Jersey's face has fine wales that can show through a plastisol print on very fine gauge fabric; interlock's flatter, denser face holds fine detail and discharge prints better. For all-over prints with tight registration, interlock is the more forgiving substrate. For large solid prints or embroidery, both are fine, though interlock's density means less puckering under a multi-colour embroidery.
Shrinkage and finishing
Both are usually sold compacted, but the mechanisms differ: jersey depends heavily on compaction and stentering to reach under 5% length shrinkage, while balanced interlock stabilises more easily. Ask for shrinkage measured on the finished, washed garment rather than on the greige roll.
Cost: Why Interlock Quotes Come In Higher
Three cost drivers explain almost all of the price difference, and none of them is the yarn price.
Interlock also takes longer to dry after dyeing and needs more careful handling in the finishing stenter to avoid edge marks. Individually none of this is large; together it justifies a fabric cost difference in the range of 10–25% at comparable yarn quality, and a smaller garment cost difference, because fabric is only one line in the costing sheet.
The trap is comparing a 160 GSM jersey quote to a 220 GSM interlock quote and concluding interlock is overpriced. Compare at equal GSM and equal yarn count, and the gap narrows to the knitting efficiency difference alone — which is a real, explainable charge rather than padding.
Which Fabric Fits Which Product
| Garment | Recommended knit | Why |
|---|---|---|
| Basic crew-neck t-shirt | Single jersey 160–180 GSM | Light, cheap, takes print well, drapes |
| Premium heavyweight tee | Interlock 200–240 GSM or heavy jersey | Structure without a fleece back |
| Polo shirt body | Interlock or piqué knit 200–220 GSM | Flat face for placket and collar, holds shape |
| Baby bodysuit and sleepwear | Interlock 190–220 GSM | Both faces smooth against skin, low curl, stable after washing |
| Matching lounge sets | Interlock 220–260 GSM | Identical face inside and out, no show-through |
| Fitted women's top or dress | Interlock or 2x2 rib | Recovery and opacity at thin panels |
| Sportswear base layer | Single jersey, polyester or blends, 130–170 GSM | Moisture movement and low weight |
| Cuffs, collars, waistbands | 2x2 rib 300–400 GSM | Mechanical stretch and snap-back |
| Lightweight lining | Single jersey 120–140 GSM | Lowest cost and weight |
Reading a Knit Spec: GSM, Yarn Count and Gauge
Most fabric quality arguments start because the approval sheet specified a GSM and nothing else. GSM alone does not define a knit — two 180 GSM jerseys can feel entirely different depending on yarn count and machine gauge.
| Parameter | What it controls | Typical spec for jersey | Typical spec for interlock |
|---|---|---|---|
| Yarn count | Softness, drape, cover | Ne 26/1 to Ne 30/1 combed cotton | Ne 30/1 to Ne 40/1 combed cotton |
| Machine gauge | Stitch density and surface fineness | 24–28 gauge | 24–28 gauge, two needle beds |
| Stitch length | Hand feel and stability | 2.7–3.2 mm | 2.3–2.8 mm |
| Courses per cm | Density along the length | 12–16 | 16–22 |
| Wales per cm | Density across the width | 14–18 | 18–24 |
| Shrinkage after wash | Fit retention | Up to 5% length, 5% width | Up to 4% length, 4% width |
A tighter stitch length gives a denser fabric that holds shape and prints better; a longer one gives a softer fabric that grows. Two mills can both supply 180 GSM jersey and hand you a different garment depending on this number, so put stitch length, yarn count, gauge and shrinkage tolerance on the approval sheet.
How to Confirm the Right Knit Before Bulk
The decision should be closed before the bulk fabric is booked, not after the first fit sample. The sequence that works:
Steps 4 to 6 are cheap and take a week. Skipping them is how a 3,000-piece order ends up with a body that grows a size after the first wash.
Sourcing Knit Fabrics From Bangladesh
Bangladesh's knit sector is vertically integrated to a degree that surprises first-time buyers: yarn spinning, circular knitting, dyeing, finishing, cutting and sewing frequently sit inside one compound, which removes a layer of transport and lead time between the knitting floor and the cutting table. TEXVENTURE is a Trusted Clothing Manufacturer in Bangladesh working with 20+ vetted factories across knitwear, wovens, denim and sweaters, with MOQ from 100 pieces per style.
For knit programmes the practical route is to specify the fabric rather than the product. Our knitwear manufacturing programmes run single jersey, interlock, rib and fleece through circular knit fabrics knitted and dyed in-house or in partner mills, so the GSM, stitch length and shrinkage you approve on a swatch are the numbers the bulk is inspected against. If you are still fixing weight and shrinkage tolerances, the guide to fabric GSM explained covers how weight interacts with yarn count and cover. Certification documentation — ISO 9001, BSCI, OEKO-TEX, SGS, Sedex and GOTS — is handled as part of our apparel manufacturing services, which matters when a European retailer asks for the chemical and social audit trail behind an interlock babywear order.
Where both fabrics meet in one style, the usual answer is a mixed programme: interlock for the body, 2x2 rib for the neckband and cuffs, single jersey for pocket bags or lining. Each needs its own approval sheet and shrinkage test, because they will not shrink identically.
Common Mistakes Buyers Make With Knit Selection
Frequently Asked Questions
Is interlock better than jersey?
Neither is better in general; they solve different problems. Interlock is denser, balanced, printable on both faces and far more dimensionally stable, which suits babywear, polos, dresses and anything that must not curl or grow. Jersey is lighter, cheaper and drapes more, which suits t-shirt bodies and promotional garments. Choose on the property your garment cannot fail on.
What is interlock fabric used for?
Interlock is used where a smooth, opaque, two-faced fabric with low curl is needed: polo shirt bodies, baby bodysuits and sleepwear, matching lounge sets, dresses, reversible garments, unlined jackets and heavier premium t-shirts. It is also common in underwear and in any style where the inside of the garment will be visible.
Is interlock warmer than jersey?
Yes, at comparable styling. Interlock is usually knitted heavier — 200–260 GSM against 160–180 GSM for a standard jersey tee — and its denser two-loop structure traps more air, so it feels warmer and dries more slowly. For hot-climate basics, jersey at the same weight will feel cooler.
Can you print on interlock fabric?
Yes, and it prints better than jersey for fine detail because both faces are flat and dense with no wales to show through. Plastisol, discharge and sublimation all work, though sublimation on cotton requires a polyester or high-poly blend. Always test the actual colourway, since dark shades on dense interlock can suffer from poor penetration.
What is the difference between interlock and rib?
Interlock has two smooth faces and moderate stretch. Rib has needles selected in a pattern that produces vertical ridges on both sides, giving much higher stretch and near-total recovery, which is why rib is used for cuffs, collars and waistbands. Interlock holds a shape; rib pulls it back into shape.
Getting the Knit Decision Right
The choice between jersey and interlock is settled by four questions: does the garment need to hold its measurements after washing, must both faces look finished, what opacity does the lightest colourway need, and what is the target weight on the tech pack. Answer those and the fabric picks itself; cost follows the answer rather than leading it.
If you are weighing both options for an upcoming knit programme, send the style, the target weight range and the colourways through the knit fabric and garment quote request and the fabric recommendation comes back with a spec sheet you can test against, not a single GSM number.