UK to Metric (mm) Knitting Needle Conversion
Find the exact millimeter measurement for every UK needle size — essential when working from British or Australian patterns or buying needles from international brands.
UK 8 = 4.0 mm · UK 9 = 3.75 mm · UK 10 = 3.25 mm · UK 6 = 5.0 mm · UK 4 = 6.0 mm
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UK to Metric (mm) Conversion Chart
All UK needle sizes from finest (UK 14) to largest (UK 000) with their mm and US equivalents.
| UK Size | Metric (mm) | US Size | Yarn Weight |
|---|---|---|---|
| UK 14 | 2 mm | US 0 | Fingering / Sock |
| UK 13 | 2.25 mm | US 1 | Fingering / Sock |
| UK 12 | 2.75 mm | US 2 | Sport / DK |
| UK 11 | 3 mm | US 2.5 | Sport / DK |
| UK 10 | 3.25 mm | US 3 | Sport / DK |
| UK 9 | 3.75 mm | US 5 | DK / Worsted |
| UK 8 | 4 mm | US 6 | DK / Worsted |
| UK 7 | 4.5 mm | US 7 | Worsted / Aran |
| UK 6 | 5 mm | US 8 | Worsted / Aran |
| UK 5 | 5.5 mm | US 9 | Bulky / Chunky |
| UK 4 | 6 mm | US 10 | Bulky / Chunky |
| UK 3 | 6.5 mm | US 10.5 | Bulky / Chunky |
| UK 2 | 7 mm | — | Bulky / Chunky |
| UK 1 | 7.5 mm | — | Bulky / Chunky |
| UK 0 | 8 mm | US 11 | Super Bulky / Jumbo |
| UK 00 | 9 mm | US 13 | Super Bulky / Jumbo |
| UK 000 | 10 mm | US 15 | Super Bulky / Jumbo |
Why You Need the mm Value
If you're buying needles outside the UK — from European, American, or Asian brands — they are very unlikely to be labeled with UK sizes. They will be labeled in mm (and possibly US sizes). Knowing the mm measurement of the UK size your pattern calls for lets you walk into any yarn shop in the world and find the right needle.
UK size numbers also appear without mm in many vintage patterns. Using this chart to find the mm value gives you a universal reference that works regardless of brand or country of purchase.