Confused with needle and hook sizes? That is because different countries use different numbering systems for knitting needles and crochet hooks.
In the US, needle sizes usually start at 0 and go up to very large sizes. In the UK, sizes start at 14 and go up to 000. To make things easier, use the chart below to compare metric (mm), UK sizes, US sizes, and crochet hook sizes in one place.
This chart is especially useful when you are following patterns from different countries or shopping for tools online.
Knitting Needle and Crochet Hook Size Conversion Chart
Metric |
UK |
US |
Hook |
| 2 mm | 14 | 0 | – |
| 2.25 mm | 13 | 1 | B |
| 2.5 mm | – | 1.5 | – |
| 2.75 mm | 12 | 2 | C |
| 3 mm | 11 | 2.5 | – |
| 3.25 mm | 10 | 3 | D |
| 3.5 mm | – | 4 | E |
| 3.75 mm | 9 | 5 | F |
| 4 mm | 8 | 6 | G |
| 4.5 mm | 7 | 7 | – |
| 5 mm | 6 | 8 | H |
| 5.5 mm | 5 | 9 | I |
| 6 mm | 4 | 10 | J |
| 6.5 mm | 3 | 10.5 | K |
| 7 mm | 2 | – | – |
| 7.5 mm | 1 | – | – |
| 8 mm | 0 | 11 | L |
| 9 mm | 00 | 13 | – |
| 10 mm | 000 | 15 | – |
| 12 – 12.75 mm | – | 17 | – |
| 15 – 16 mm | – | 19 | – |
| 19 mm | – | 35 | – |
| 20 mm | – | 36 | – |
| 25 mm | – | 50 | – |
Tip: Always follow the size recommended in your pattern and make a small gauge swatch first. Different people knit and crochet with different tension, so you may need to go up or down a size to get the right result.
Related Guides
- Yarn Weights Explained: How to Choose the Right Yarn and Needle or Hook Size
- The Ultimate Beginner’s Guide to Crochet and Knitting
- Yarn, Yarn Weight and Related Needle / Hook Sizes
- Yarn Recommendations by Project — find yarn suggestions that work with common hook/needle sizes
If you want to browse yarn by thickness instead, you can also use:
