Yarn weight chart and wraps per inch calculator

How to measure wraps per inch

1. Wind the yarn around something straight and even, like a pencil or a ruler, for a few inches.
2. Lay each wrap snugly against the one before it, with no gaps and no overlaps. Don't stretch the yarn: let it sit as it would in the ball.
3. Count the wraps along 2 in (5 cm) of the pencil. Count again in another place, and use the middle of the two counts.
4. Enter the count and the length you counted along.

How it works

Wraps per inch (WPI) is the number of wraps divided by the length in inches. A length in centimeters is changed to inches first. The calculator then finds which yarn weights have that number in their range on the Craft Yarn Council's wraps per inch chart.

wraps per inch = wraps ÷ length in inches
length in inches = length in cm ÷ 2.54

Example: 20 wraps along 2 in is 20 ÷ 2 = 10 wraps per inch. That's inside the range for medium (4) yarn, 9 to 12, and no other, so it's most likely a yarn sold as worsted, afghan or aran. For knitting, start a swatch on 4.5 to 5.5 mm needles (US 7 to 9).

The ranges overlap, so many counts fit more than one weight. 24 wraps along 2 in is 12 wraps per inch, which fits fine (2), light (3) and medium (4). A swatch settles it: compare your stitches in 4 in with the gauges in the chart below.

Yarn weight chart

The eight weights of the Craft Yarn Council's standard yarn weight system, from 0 (lace) to 7 (jumbo). Many yarn labels show the number inside a small picture of a yarn ball. Gauges are the usual number of stitches in 4 in (10 cm): stockinette for knitting and single crochet for crochet.

Needles and hooks for each weight

The needle and hook sizes most often used for each weight. Your pattern's size comes first: it's the one that gave the designer their gauge.

* Lace: the crochet gauge is in double crochet, and crochet thread can also use a steel hook of 1.4 to 1.6 mm (steel sizes 6 to 8; steel hook numbers get bigger as the hook gets smaller). Lace yarn is often worked on much bigger needles or hooks than these to make an open, lacy fabric, so follow your pattern's gauge.

Sources: the Craft Yarn Council's Standard Yarn Weight System and wraps per inch chart, checked October 2026. The council gives these ranges as guidelines, not rules.

Tips

• Wraps per inch is a rough guide. Wrap more tightly and you'll count more wraps. If you have a yarn whose weight you know, wrap it the same way to check your tension.
• For thick yarn, count along 3 or 4 in (8 or 10 cm). With only a few wraps per inch, one wrap more or less changes the answer a lot.
• Fuzzy, bouclé and other textured yarns are hard to wrap evenly. For those, a swatch tells you more than wraps per inch.
• Swatch with a needle or hook from the middle of the suggested sizes, wash it, and count your stitches in 4 in. The cast-on calculator turns that gauge into a stitch count for your project.
• Swapping yarn in a pattern? Pick the same weight, then use the yarn substitution calculator to see how many skeins to buy.