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Worsted and Weave

Reference Charts

Size charts, the weight system, and a yardage matrix - the numbers, without the preamble.

A knitting gauge ruler laid across a swatch with a tape measure alongside

The numbers, without the preamble. Every table in this section is either reproduced from a published standard or computed from one, and every page says which.

Most of what these pages contain is the Craft Yarn Council's Standard Yarn Weight System, which is the industry's own mapping of yarn thickness to gauge, needle size and hook size. We compiled it; we did not derive it, and we have not adjusted or averaged anything.

The one page here that is genuinely ours is the yardage method, and it is honest about what it is: an arithmetic procedure you run on your own swatch, rather than a single number we made up for you.

Everything in this section

Which chart you need

  • [Yarn weight chart](/reference/yarn-weight-chart) - all eight categories with knit gauge, crochet gauge and both tool ranges. Start here if you are holding a yarn and do not know what it is.
  • [Needle size chart](/reference/needle-size-chart) - US to metric conversions plus the range each yarn weight calls for. Start here if you are holding a needle with no marking.
  • [Hook size chart](/reference/hook-size-chart) - US letters to millimeters, plus the steel scale that runs backwards.
  • [How much yarn do I need](/reference/how-much-yarn-do-i-need) - the area method, standard finished sizes, and published yardage per skein.
  • [How to substitute yarn](/reference/yarn-substitution) - the five checks a safe substitution needs, in order.

The one thing to understand about all of them

Gauge is the definition and the tool size is a suggestion. A yarn is category 4 because it knits at 16 to 20 stitches over 4 inches, not because the label says 5mm. If you knit tightly you may need 5.5mm to land inside that range; if you knit loosely, 4.5mm. Both of you are using category 4 yarn correctly.

Most people have this backwards, and it is the single most common cause of a garment coming out the wrong size. Match the fabric, not the tool.

Why the yardage page has no single number

Because we would have to invent one. Yardage depends on your gauge, your stitch, your yarn's density and your finished size, and a blanket is anywhere from 1,000 to 4,500 yards depending on those four. Every page that answers with one number is guessing on your behalf.

What we give you instead is exact: the finished areas for standard sizes, published yardage per skein for real yarns, and the arithmetic to turn your own swatch into a shopping list. It takes two minutes longer and it does not leave you three skeins short in a discontinued dye lot.

Two rules that apply across every page here

  1. Buy on yards, never on skeins. Two 100g skeins of the same weight category can differ by 50 yards or more depending on fiber density. Skein counts do not transfer between yarns.
  2. Swatch when you swap. Every substitution changes something, and the swatch is where you find out what. Wash and block it the way you will treat the finished object - superwash wool in particular grows when wet and often does not fully recover.

If a standard changes

These pages get revised with it. The tables here are compiled from published sources rather than remembered, and the sources are linked at the bottom of every page so you can check them yourself. That is the whole method, and it is set out in full on how we pick.

Before you buy anything

Everyone in this category says they tested twenty of these. We have not tested any, and we say so. What we publish instead is the manufacturers' own specifications, the arithmetic, and live prices with the date attached.

How we pick