Wraps Per Inch (WPI) Reference Chart

Wraps per inch (WPI) measures how many strands of yarn fit snugly side by side across one inch when wound around a ruler or WPI tool. It's the standard way to identify an unlabeled skein, since it measures the yarn itself rather than relying on a label that might be missing, faded, or from a brand using its own naming.

WPI ranges by yarn weight category
Category	Typical WPI
Lace	30+
Light Fingering	19-22
Fingering / Sock	14-18
Sport	12-13
DK	11-12
Worsted	9-10
Aran	8-9
Bulky	6-7
Super Bulky	5-6
Jumbo	1-4

These ranges overlap at the edges on purpose. WPI is a wound measurement, and how snugly you wrap changes the count by a wrap or two either way. Wrap the same yarn three times and average the results before trusting the number, especially if it lands right on a boundary between two categories.

Fiber and ply affect the reading too. A loosely spun single will compress more than a tightly plied yarn of the same actual thickness, so two yarns with identical WPI can still knit up at different gauges. Treat WPI as a strong first identification, then confirm with a gauge swatch before committing a full project to an unlabeled skein.

Frequently Asked Questions

What do I wrap the yarn around to measure WPI?

A wraps-per-inch tool, a ruler, or even a pencil works. Wrap the yarn around it snugly with strands touching but not overlapping or stretched, then count how many wraps fit in one inch.

My yarn measures between two categories on this chart. Which one is it?

Wrap it a few more times and average your counts, then check it against the needle size and gauge that feels right when you swatch. WPI narrows the range, but the swatch is the final word.

Does WPI work for novelty or textured yarn?

Less reliably. Boucle, chenille, and other heavily textured yarns compress unevenly when wrapped, so WPI readings on those are rougher estimates than on smooth, evenly spun yarn.