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What does that number on the yarn label mean?

Have you been looking at a yarn label/website and seen a mysterious number inside of a cartoon ball of yarn? Like this one:

What does that number mean?

That number (which ranges from 0 to 6) is an indication of the thickness of the yarn. In our example above, the ‘4’ would indicate that the yarn is a medium weight yarn.

The symbols were devised by the Craft Yarn Council, and have a standardized usage. You can look up the exact thicknesses that correspond to each number on the Craft Yarn Council’s website.

Oftentimes, though, you won’t have to. It’s pretty rare that you’ll see the number alone… it’s usually accompanied by more information on the yarn label:

When available, you should go by this more detailed, gauge information.

Why you should pay attention to gauge, instead

Even though the number is cute and catchy, it’s not the most accurate way to categorize your yarn. Each number is actually a category that contains a group of thicknesses.

For example, ‘4’ contains: worsted, afghan and aran yarns… and the recommended needle size ranges from 7 to 9 (and hooks from I to K). That’s quite a range!

When selecting yarn for a project, you want to make sure you’re getting the right number of stitches per inch. Since the number represents a range of yarn thicknesses, seeing a ‘4’ on the yarn label doesn’t guarantee you’ve found the right thickness! You want to make sure that your yarn works up to the right number of stitches per inch.

Of course, the best way to do this is by doing a gauge swatch… but since yarn stores don’t usually make swatches with yarn you haven’t bought yet, the best shortcut is by reading the gauge info. If you’re looking for a worsted weight yarn that works up to 5 sts/inch, then finding this information on the label is a good clue you’re on track!

While the number is a helpful guide to yarn thickness, it isn’t a replacement for reading gauge information! Read the gauge info on the yarn label, and you’ll be assured that you’re finding the right yarn for your project!


  1. S. Seliskar SAYS...

    Very helpful, thanks