How to Tell the Difference Between Woven and Knit Fabric

When you think of woven fabrics, think of fabric you’d use to make a quilt or curtains or upholstery. Woven fabric is generally crisp and not stretchy*. It can be as thin as chiffon or as thick as denim.

*Some woven fabrics, like stretch denim or stretch poplin, have spandex woven in to give it some stretch. A stretch poplin may have 15% stretch across the grain, which means a 10″ piece of fabric can stretch up to 11.5″.

When you think of knit fabrics, think of t-shirts and leggings. Knit fabric is usually stretchy and supple. It can be as thin as mesh or as thick as sweatshirt fleece.

Knit fabrics tend to offer a superior amount of stretch compared with woven, perhaps 30-50% for a t-shirt or up to 100% for something like a nylon spandex. 50% stretch would mean a 10″ piece of fabric can stretch up to 15″. 100% would mean a 10″ piece of fabric could stretch up to 20″. That’s quite a difference from the 11.5″ from the stretch poplin example.

This handy little drawing (courtesy of Threads magazine) is a close-up of how woven fabric is constructed. Notice it’s a sort of basket-weave pattern, with the threads running perpendicular to each other. Each thread is separate from the next, meaning that when it’s cut, the edges fray.

This is a close up of a knit fabric. Knit fabric is called knit fabric because it is literally knit- very similar to the way you would knit a sweater with a ball of yarn and knitting needles. It’s just usually done on a much smaller scale: tiny needles, a very thin “yarn”. Knit fabric is all one continuous piece of thread (or close to it), so a raw edge usually won’t unravel the way it would on a woven fabric. And all of those interlocking loops are what allows for the natural stretchiness.

HOW TO TELL THE DIFFERENCE

What if the fibers are so tiny that you can’t tell if they’re crossed or looped? One way to find out if it’s knit or woven is to test how it stretches.

Because knit fabric is made from one continuous thread (much like the one continuous yarn in your handknitting), it stretches all over. Woven fabrics, on the other hand, will only stretch diagonally or as a sewer might say, on the bias.

Grab the fabric in question and pull it gently from side to side, top to bottom, diagonally. Does it stretch easily in all directions? If so, it’s probably a knit fabric. If you can only get a bit of stretch diagonally, it’s probably a woven fabric.