Woven fabric is made of two sets of threads crossing at right angles, so it is stable and barely stretches except on the bias. Knit fabric is made of one yarn formed into rows of interlocking loops, so it stretches, often in both directions, and springs back. To tell them apart, pull the fabric crosswise and look closely: a woven barely gives and shows a grid of threads, while a knit stretches easily and shows rows of tiny V-shaped loops.
Woven and knit at a glance
| Woven | Knit | |
|---|---|---|
| Structure | Lengthwise warp threads and crosswise weft threads crossing at right angles | One continuous yarn looped into rows |
| Stretch | Little or none along the grain, some on the bias, unless it contains elastane | Stretches across, often lengthwise too, and recovers |
| Cut edges | Fray | Do not fray; jersey edges curl |
| Typical fabrics | Poplin, lawn, linen, denim, chambray, satin | Jersey, interlock, rib, French terry, ponte, sweatshirt fleece |
| Machine needle | Universal, or microtex for fine fabrics | Ballpoint, or stretch for knits with elastane |
| Stitch | Straight stitch | Narrow zigzag, stretch stitch or serger |
| Seam allowance (Sewly default) | 1.5 cm (5/8 in) | 1 cm (3/8 in) |
| Hem | Double fold or blind hem | Single fold with a twin needle or zigzag |
| Ease | Always positive | Can be zero or negative |
How to tell woven from knit: five quick tests
- Look at the surface. Zoom in with your phone camera. A knit shows little columns of V shapes on the right side of jersey, or loops; a woven shows a grid of crossing threads, or the diagonal lines of a twill.
- Pull it crosswise. A knit stretches easily and springs back. A woven barely moves.
- Pull it diagonally. A woven gives on the bias but not along the straight grain. A fabric that stretches in every direction is a knit.
- Check a cut edge. Woven edges fray into loose threads. Single jersey curls: the lengthwise edges roll toward the right side, the crosswise edges toward the wrong side.
- Pull out a thread. From a woven, you can pull straight single threads off the edge. From a knit, the yarn comes out crimped and wavy, and a crosswise edge may unravel or ladder like tights.
Stretch wovens are still wovens
Stretch denim, stretch sateen and stretch poplin contain a little elastane, usually 2 to 5 %. They give across the width for comfort, but they fray, press and sew like wovens and use woven patterns. They do not stretch enough to replace a knit in a pattern drafted for knits.
Types of knit and how stretchy they are
Knits differ widely in stretch, and patterns for knits are drafted for a certain amount. Measure it: fold the fabric along a crosswise line, hold 10 cm (4 in) against a ruler and stretch until it resists. If it reaches 15 cm (6 in), the stretch percentage is 50 %.
| Stretch | Examples | Good for |
|---|---|---|
| Under 25 % | Ponte, double knit, sweatshirt fleece | Structured dresses, pencil skirts, sweatshirts |
| 25 to 50 % | Cotton jersey, interlock, French terry | T-shirts, relaxed dresses, joggers |
| 50 to 75 % | Cotton elastane jersey, rib knit | Fitted tees, neckbands, cuffs |
| Over 75 % | Activewear and swimwear knits | Leggings and close-fitting sportswear |
Types of woven
- Plain weave (poplin, lawn, voile, linen, calico): one thread over, one under. It looks the same on both sides and is the most stable.
- Twill (denim, gabardine, drill): diagonal lines on the surface. It drapes a little more, hides creases and wears hard.
- Satin weave (satin, sateen): long floating threads give a smooth sheen, at the price of slipperiness when you sew.
Why it matters for your pattern
Patterns are drafted for one or the other. A knit pattern has less ease, sometimes negative ease, because the fabric stretches to fit; a woven pattern needs ease to move in and an opening to get in, such as a zip, buttons or a keyhole. In Sewly, for example, a regular-fit top gets 10 cm (4 in) of ease at the bust in a woven but 5 cm (2 in) in a knit, and a fitted knit top is drafted 2 cm (3/4 in) smaller than the body. Choose a round neck on a woven top with no opening and Sewly adds a back keyhole, because a woven round neck cannot stretch over your head.
Sewing them: the key differences
- Needles: a universal 80/12 for medium wovens, a microtex for fine ones; a ballpoint 75/11 or 80/12 for jersey, a stretch needle for knits with elastane.
- Stitches: a straight stitch of 2.5 mm for wovens. For knits, a narrow zigzag (about 0.5 to 1 mm wide, 2.5 to 3 mm long) or the stretch stitch, so seams stretch without snapping.
- Seam finishes: wovens fray, so finish the edges; knits do not need it, although a serger makes them neater.
- Cutting: never let a knit hang off the table while you cut, and line the pattern's grainline up with a column of loops.
- Pressing: lift and lower the iron on knits; sliding it stretches them.
The whole knit workflow, from needles to hems, is in sewing knit fabrics on a regular machine. Some patterns, such as the T-shirt, are drafted for knits only.
Which one for your project?
Let the garment decide. Choose a woven when it needs structure, crisp edges, sharp pressing or a closure: skirts with a waistband and zip, shift dresses, blouses, tailored shorts, tote bags and aprons. Choose a knit when it should pull on and move with you without fastenings: T-shirts, tanks, sweatshirts, hoodies and leggings. Some shapes exist in both versions, such as pull-on trousers or a simple dress. There a knit gives a softer, sportier result and a woven a crisper, smarter one, as long as the pattern is drafted for the fabric you choose. For a first project, a stable woven is the easier of the two to cut and sew.
Common mistakes
- A woven in a knit pattern: the garment comes out too tight and may not go on at all.
- The stretch running the wrong way: the greatest stretch must go around the body, not up and down.
- Stretching knit seams as you sew: they wave. Let the feed dogs move the fabric, lighten the presser foot pressure or use a walking foot.
- Ignoring recovery: a knit that does not spring back bags out at the knees and elbows.
- Treating a stretch woven as a knit: 3 % elastane is comfort, not a substitute for jersey.