Wraps Per Inch Chart (Free Printable)

Wraps per inch (aka. WPI) is a way to identify yarn weight.

If you have mystery yarn without a label, use wraps per inch to figure out its yarn weight. All you need is a ruler and pencil.

Wraps per inch was originally developed by weavers working with yarn, but us knitters can also benefit from this nifty technique.

How to Determine Wraps Per Inch

1. Wrap the mystery yarn around a pencil for a few inches. The yarn should be snug but not tight, and the wraps should lay side by side against each other.

2. Carefully lay the pencil on a flat surface. Count how many wraps there are within an inch. This is the yarn’s WPI.

3. I’ve counted 8 WPI for my mystery yarn.

4. Refer to the WPI chart below to reveal the mystery yarn’s weight. This chart is based on information from the Craft Yarn Council.

According to the WPI chart, 8 wraps per inch falls within the range for bulky weight yarn.

Mystery solved!

Wraps Per Inch Chart

Yarn Weight	WPI	Needle Size	Knitting Gauge Per Inch
0 – Lace	30-40	1.5-4.5mm	8-10
1 – Super Fine	14-30	2.25-3.25mm	6-8
2 – Fine	12-18	3.25-3.75mm	5-6.5
3 – Light	11-15	3.75-4.5mm	5-6
4 – Worsted	9-12	4.5-5.5mm	4-5
5 – Bulky	6-9	5.5-8mm	3-4
6 – Super Bulky	5-6	8-12.75mm	1.75-2.75
7 – Jumbo	1-4	12.75mm+	1.5 or less

Download and print out the wraps per inch chart below so you’ll have it handy when you encounter mystery yarn!

Tips for Measuring with WPI

If you want to be very accurate, measure the WPIs along different points along the pencil. Then take an average of the wraps.

The accuracy of the WPI will depend on the tension of how tightly or loosely you wrap.

To practice your wrapping tension, use a yarn whose yarn weight you already know.

When wrapping thicker yarns, wrap for several inches and then divide by the number of inches.This gives a more accurate reading.

For example, if I had yarn that looked like bulky or super bulky, I would wrap it for 3 inches and count the wraps. Then divide the number by three for the WPI.

If you’re using mystery yarn to knit a pattern, make sure you match the pattern’s knitting gauge too!

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