Have you ever found yarn with no label, uh yea, how do you know the weight of the yarn, #4 worsted or #3 DK? There is a simple method for finding this out, it’s called Wraps Per Inch or WPI. This topic came up at a recent crochet meet-up because there was donated yarn without labels. So, I pulled up the Craft Yarn Council website to find the WPI chart on my phone. I quickly showed the group how to measure using one of the methods below, this worked out perfectly.

Wraps Per Inch (WPI) by yarn weight

CYC weight	WPI
0 Lace	30-40+
1 Super Fine	14-30
2 Fine	12-18
3 Light	11-15
4 Medium	9-12
5 Bulky	6-9
6 Super Bulky	5-6
7 Jumbo	1-4

This chart is based on WPI information shared by industry experts and the two WPI lists noted below.

http://woolery.com/yarns/help-withyarn-sizes/wraps-per-inch.html

http://www.ravelry.com/help/yarn/weights

Below I tested this method with yarn from my stash (with labels) to confirm. Left is Cascade 220 Superwash, #4 Worsted, and right is Queensland Dungarees #2fine/sport.

The Test

I used 2 methods to confirm these weights. First is wrapping around a ruler for 2-3″, not too tight or loose, make sure wraps are close together and not overlapping. This shows 10 wraps to the inch. This falls right in the middle of the WPI chart for #4 Worsted weight. The next method I wrapped around a pencil, again not loose or tight, pushed it together, and measured on my gauge ruler. I got 18 WPI, again I made the higher end of the #2 Fine/Sport weight.

So, if you have inherited shopped, or found yarn without a label, have no fear. Tip: I always have a pen and tape measure in my purse. you never know.

Further information

• https://www.craftyarncouncil.com/standards/how-measure-wraps-inch-wpi
• https://www.interweave.com/article/crochet/wpi-guide-yarn-substitution/