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Knitting Needle Size Converter
US 8, 5 mm and UK 6 are the same needle. Type any one of them and get the other two, or find the nearest standard size for an odd millimetre measurement.
Knitting needle size chart
| US | Metric | UK / Canadian |
|---|---|---|
| 0 | 2 mm | 14 |
| 1 | 2.25 mm | 13 |
| 1½ | 2.5 mm | 12 |
| 2 | 2.75 mm | — |
| 2½ | 3 mm | 11 |
| 3 | 3.25 mm | 10 |
| 4 | 3.5 mm | 9 |
| 5 | 3.75 mm | — |
| 6 | 4 mm | 8 |
| 7 | 4.5 mm | 7 |
| 8 | 5 mm | 6 |
| 9 | 5.5 mm | 5 |
| 10 | 6 mm | 4 |
| 10½ | 6.5 mm | 3 |
| — | 7 mm | 2 |
| — | 7.5 mm | 1 |
| 11 | 8 mm | 0 |
| 13 | 9 mm | 00 |
| 15 | 10 mm | 000 |
| 17 | 12 mm | — |
| 19 | 15 mm | — |
| 35 | 19 mm | — |
| 50 | 25 mm | — |
A dash means that system has no size at that millimetre. US 1½ and 2½ exist on sock needles from some makers and not others.
Reading the three systems
Metric is the needle's diameter in millimetres and the only true measurement of the three. US and UK sizes are labels attached to particular millimetre sizes, so when two systems disagree, the millimetres win. If you keep one note of a needle size, keep the metric one.
US sizes count up as the needle gets bigger, but in uneven steps: sizes 0 to 10 climb by a quarter or half millimetre, then the scale jumps (10½ is 6.5 mm, 11 is 8 mm, 13 is 9 mm) and the numbers stop meaning much. There is no US 12, 14 or 16.
UK sizes (also used in Canada and in older Australian patterns) run backwards, because they come from the old imperial wire gauge: UK 14 is a 2 mm needle and UK 000 is 10 mm. Any UK pattern from before about 1980 uses them, and many still list them alongside metric. A "size 8" needle in a British vintage pattern is 4 mm, not the 5 mm a US 8 would be. That single confusion is the most common way a garment comes out a size wrong.
Needle size by yarn weight
The range the Craft Yarn Council suggests for each yarn weight. It's a starting point for the swatch, not a rule: the gauge calculator tells you whether to move up or down a size once you've measured.
| Yarn weight | Needle range | Stockinette per 4 in |
|---|---|---|
| Lace (0) | 1.5 to 2.25 mm | 33 to 40 |
| Fingering (1) | 2.25 to 3.25 mm | 27 to 32 |
| Sport (2) | 3.25 to 3.75 mm | 23 to 26 |
| DK (3) | 3.75 to 4.5 mm | 21 to 24 |
| Worsted (4) | 4.5 to 5.5 mm | 16 to 20 |
| Bulky (5) | 5.5 to 8 mm | 12 to 15 |
| Super bulky (6) | 8 to 12.75 mm | 7 to 11 |
| Jumbo (7) | 12.75 to 25 mm | 1 to 6 |
Crocheting instead? The crochet hook size converter has the matching chart for hooks, including the US letter sizes.