US to UK Knitting Needle Size Conversion
US and UK needle sizes run in opposite directions — a US 8 is not a UK 8. Find the correct UK equivalent for every US size with this complete chart.
US 8 = UK 6 (not UK 8) · US 6 = UK 8 (not UK 6) · Always verify both numbers against mm
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US to UK Conversion Chart
Every US needle size with its UK equivalent, millimeter measurement, and yarn weight. Sizes without a UK equivalent use metric sizing (above UK 000).
| US Size | UK Size | Metric (mm) | Yarn Weight |
|---|---|---|---|
| US 000000 | — (use mm) | 1.5 mm | Lace / Cobweb |
| US 00000 | — (use mm) | 1.75 mm | Lace / Cobweb |
| US 0 | UK 14 | 2 mm | Fingering / Sock |
| US 1 | UK 13 | 2.25 mm | Fingering / Sock |
| US 1.5 | — (use mm) | 2.5 mm | Fingering / Sock |
| US 2 | UK 12 | 2.75 mm | Sport / DK |
| US 2.5 | UK 11 | 3 mm | Sport / DK |
| US 3 | UK 10 | 3.25 mm | Sport / DK |
| US 4 | — (use mm) | 3.5 mm | DK / Worsted |
| US 5 | UK 9 | 3.75 mm | DK / Worsted |
| US 6 | UK 8 | 4 mm | DK / Worsted |
| US 7 | UK 7 | 4.5 mm | Worsted / Aran |
| US 8 | UK 6 | 5 mm | Worsted / Aran |
| US 9 | UK 5 | 5.5 mm | Bulky / Chunky |
| US 10 | UK 4 | 6 mm | Bulky / Chunky |
| US 10.5 | UK 3 | 6.5 mm | Bulky / Chunky |
| US 11 | UK 0 | 8 mm | Super Bulky / Jumbo |
| US 13 | UK 00 | 9 mm | Super Bulky / Jumbo |
| US 15 | UK 000 | 10 mm | Super Bulky / Jumbo |
| US 17 | — (use mm) | 12 mm | Super Bulky / Jumbo |
| US 19 | — (use mm) | 15 mm | Super Bulky / Jumbo |
| US 35 | — (use mm) | 19 mm | Super Bulky / Jumbo |
| US 36 | — (use mm) | 20 mm | Super Bulky / Jumbo |
| US 50 | — (use mm) | 25 mm | Super Bulky / Jumbo |
Why US and UK Numbers Are Reversed
This is the most common source of knitting needle confusion, and it trips up even experienced knitters. The two systems were developed independently and they run in completely opposite directions:
US system: Larger numbers = larger needles. US size 0 is tiny (2.0 mm); US size 50 is enormous (25 mm).
UK/British system: Larger numbers = smaller needles. UK size 14 is tiny (2.0 mm); UK size 000 is 10.0 mm.
This means a pattern written in the UK that calls for "size 8 needles" wants 4.0 mm needles — which is US size 6, not US size 8. Using the wrong size will throw off your gauge and change the finished dimensions of your project.
The safest approach: always verify against the millimeter measurement. If a pattern lists only a UK or US size without mm, use this chart to find the mm equivalent, then use needles you can confirm are that diameter.
Australian and Canadian patterns
Australia and Canada historically used the same numbering system as the UK. If you're working from an Australian or Canadian pattern, treat the needle sizes as UK sizes.
Old vs. modern British patterns
Since the 1970s, UK patterns have increasingly moved to metric (mm) sizing, often listing UK size alongside mm. Very old British patterns may list only the UK number. For needles larger than UK 000 (10 mm), modern British patterns use metric sizing because the traditional UK scale does not extend that far.