Yarn Weight Numbers Explained: What 0 to 7 Actually Means

Yarn weight has nothing to do with how heavy the ball is. It means how thick the strand is, and it is the single most important number on a yarn label, because it decides what hook you use and how big your finished piece comes out.

The confusing part is that every country named the same thicknesses differently, and then a numbering system was added on top. Here is the whole thing in one place.

The full chart

The number is the reliable part. If a pattern says weight 4 and your yarn label shows a 4 inside a little skein symbol, you are matched, whatever the label calls it in words.

The naming traps

"Ply" does not mean what it sounds like. In UK and Australian naming, ply is a thickness label, not a count of strands. A modern "8 ply" yarn is not necessarily made of eight plies. Treat it as a name.

Worsted and Aran are not quite the same. Both sit at number 4, but Aran usually runs slightly thicker. Within amigurumi that difference rarely matters. In a fitted garment it does.

DK is number 3, not 4. This one catches people out constantly, because DK feels like a middle weight and 4 is labelled "Medium". If a pattern calls for worsted and you use DK, your piece comes out noticeably smaller.

Fingering, sock and 4 ply are the same thing. Three names, one weight, number 1.

Which weight does amigurumi want?

Weight 4, worsted, almost always. It is thick enough that the stitches are easy to see and count while you are learning, and it builds a firm fabric quickly.

Yon Yarn is a weight 4 worsted, a 68% cotton and 32% nylon blend chosen so the ply does not separate under the hook.

Two things worth knowing:

• Go smaller on the hook than the label says. A worsted label will suggest 5 to 6.5mm. For amigurumi most people work at 3.5 to 4mm, because stuffed pieces need fabric dense enough to hold stuffing in. Our guide to gauge in amigurumi explains the light test for checking density.
• Weight is not the only thing that matters. A fuzzy weight 4 yarn hides your stitches so you cannot count them, and a loosely spun one splits. Our guide to the best yarn for amigurumi covers fibre and construction.

What if the label has no number?

Plenty of yarn, especially from small dyers and older stock, never carries the numbering symbol. Two ways to work it out:

Use the recommended hook size. Work backwards through the chart above. A label suggesting 5.5mm is almost certainly a 4.

Use metres per gram. Divide the length by the weight of the ball. Roughly:

• More than 3.5 m/g: weight 1 or finer
• Around 2.5 to 3.5 m/g: weight 3, DK
• Around 1.5 to 2.5 m/g: weight 4, worsted
• Less than 1.5 m/g: weight 5 or heavier

A 50g ball with 100m is 2 m/g, which lands squarely in worsted. Our guide to reading a yarn label covers the other symbols.

Substituting a weight you do not have

You can go one number away and usually still get a good result, as long as you adjust the hook to match and accept a size change. Going from 4 to 3 makes the piece smaller and denser; 4 to 5 makes it bigger and looser.

For amigurumi that is usually fine, because nothing has to fit. For anything worn, swatch first.

The short version

• The number is thickness, and it is the part that travels between countries.
• DK is 3. Worsted and Aran are 4. Do not let the word "Medium" mislead you.
• Amigurumi wants weight 4, worked on a smaller hook than the label suggests.

If reading the rest of the pattern is the harder part, our free Pattern Trainer teaches crochet notation from a single round through to a complete multi-piece pattern, with no purchase and no account required.