Metric (mm) to UK Knitting Needle Size Conversion
Find the UK needle size for any millimeter measurement. Essential for working from European patterns with British-standard needles, or understanding UK patterns when you only have mm needles.
4.0 mm = UK 8 · 4.5 mm = UK 7 · 5.0 mm = UK 6 · 5.5 mm = UK 5 · 6.0 mm = UK 4
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Metric (mm) to UK Conversion Chart
Every standard metric needle size with its UK equivalent. Sizes without a UK equivalent (above 10mm or at non-standard increments) are shown with the nearest UK size.
| Metric (mm) | UK Size | US Size | Yarn Weight |
|---|---|---|---|
| 1.5 mm | — (use mm) | US 000000 | Lace / Cobweb |
| 1.75 mm | — (use mm) | US 00000 | Lace / Cobweb |
| 2 mm | UK 14 | US 0 | Fingering / Sock |
| 2.1 mm | — (use mm) | — | Fingering / Sock |
| 2.25 mm | UK 13 | US 1 | Fingering / Sock |
| 2.4 mm | — (use mm) | — | Fingering / Sock |
| 2.5 mm | — (use mm) | US 1.5 | Fingering / Sock |
| 2.7 mm | — (use mm) | — | Fingering / Sock |
| 2.75 mm | UK 12 | US 2 | Sport / DK |
| 3 mm | UK 11 | US 2.5 | Sport / DK |
| 3.25 mm | UK 10 | US 3 | Sport / DK |
| 3.3 mm | — (use mm) | — | Sport / DK |
| 3.5 mm | — (use mm) | US 4 | DK / Worsted |
| 3.6 mm | — (use mm) | — | DK / Worsted |
| 3.75 mm | UK 9 | US 5 | DK / Worsted |
| 3.9 mm | — (use mm) | — | DK / Worsted |
| 4 mm | UK 8 | US 6 | DK / Worsted |
| 4.2 mm | — (use mm) | — | DK / Worsted |
| 4.5 mm | UK 7 | US 7 | Worsted / Aran |
| 4.5 mm | — (use mm) | — | Worsted / Aran |
| 5 mm | UK 6 | US 8 | Worsted / Aran |
| 5.1 mm | — (use mm) | — | Worsted / Aran |
| 5.4 mm | — (use mm) | — | Worsted / Aran |
| 5.5 mm | UK 5 | US 9 | Bulky / Chunky |
| 5.7 mm | — (use mm) | — | Bulky / Chunky |
| 6 mm | UK 4 | US 10 | Bulky / Chunky |
| 6 mm | — (use mm) | — | Bulky / Chunky |
| 6.3 mm | — (use mm) | — | Bulky / Chunky |
| 6.5 mm | UK 3 | US 10.5 | Bulky / Chunky |
| 6.6 mm | — (use mm) | — | Bulky / Chunky |
| 7 mm | UK 2 | — | Bulky / Chunky |
| 7.5 mm | UK 1 | — | Bulky / Chunky |
| 8 mm | UK 0 | US 11 | Super Bulky / Jumbo |
| 9 mm | UK 00 | US 13 | Super Bulky / Jumbo |
| 10 mm | UK 000 | US 15 | Super Bulky / Jumbo |
| 12 mm | — (use mm) | US 17 | Super Bulky / Jumbo |
| 15 mm | — (use mm) | US 19 | Super Bulky / Jumbo |
| 19 mm | — (use mm) | US 35 | Super Bulky / Jumbo |
| 20 mm | — (use mm) | US 36 | Super Bulky / Jumbo |
| 25 mm | — (use mm) | US 50 | Super Bulky / Jumbo |
When Metric Sizes Have No UK Equivalent
Some metric sizes don't have a UK equivalent because the UK scale doesn't cover every 0.25mm increment. For needles above 10mm, the UK scale stops entirely — modern British patterns use metric sizing for those sizes. If your needle is labeled in a mm size that doesn't appear in the UK column, use the nearest UK size that produces the correct gauge for your project.