Knitting reference
Knitting needle sizes & conversion chart
Old UK needle numbers run backwards, US numbers use a different system again, and modern patterns usually use millimetres. This is the quick version.
| Metric | Old UK / imperial | US |
|---|---|---|
| 2 mm | 14 | 0 |
| 2.25 mm | 13 | 1 |
| 2.75 mm | 12 | 2 |
| 3 mm | 11 | — |
| 3.25 mm | 10 | 3 |
| 3.5 mm | — | 4 |
| 3.75 mm | 9 | 5 |
| 4 mm | 8 | 6 |
| 4.5 mm | 7 | 7 |
| 5 mm | 6 | 8 |
| 5.5 mm | 5 | 9 |
| 6 mm | 4 | 10 |
| 6.5 mm | 3 | 10½ |
| 7 mm | 2 | — |
| 7.5 mm | 1 | — |
| 8 mm | 0 | 11 |
| 9 mm | 00 | 13 |
| 10 mm | 000 | 15 |
| 12.5 mm | — | 17 |
| 15 mm | — | 19 |
| 19 mm | — | 35 |
| 25 mm | — | 50 |
Why do old UK knitting needle sizes look backwards?
Older British patterns often use imperial needle numbers. In that system, the larger the number, the smaller the needle: an old UK 14 is about 2mm, while an old UK 8 is 4mm.
That is why a vintage pattern asking for a pair of No. 10 needles means roughly 3.25mm — not a giant modern 10mm needle. It is an easy mistake to make once, and quite enough.
What if the US and metric conversion looks slightly different elsewhere?
Needle numbering is not perfectly universal across manufacturers and older charts. If a needle or pattern gives a metric size, treat that as the primary value. The Craft Yarn Council also recommends relying on the millimetre measurement where number systems vary.
And for an actual project, the pattern gauge still wins: if your swatch is too tight or too loose, change needle size until the finished gauge matches rather than clinging heroically to the number printed on the pattern.
Needle size is not the same thing as yarn weight
DK does not have one compulsory needle size, and neither does aran, 4-ply or chunky yarn. Patterns choose a needle size to create a particular fabric and gauge. A loose lace fabric may use a much larger needle than a dense rib in a similar yarn.
For the broader yarn-weight ranges and typical needle sizes, use our yarn weight chart rather than trying to reverse-engineer the yarn from the needle alone.
Conversion data checked against the Craft Yarn Council metric/US standards and UK imperial charts from established UK knitting retailers. Manufacturer sizing can vary slightly.
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