Needle & Hook Size Chart
Millimetres, US and UK sizes for knitting needles, crochet hooks and steel hooks.
Needle and hook sizes are written three different ways, and the numbers run in opposite directions depending on the system — UK needle numbers get smaller as the needle gets thicker, and steel crochet hooks get finer as the number goes up. The millimetre diameter is the only measurement that never changes meaning, so read across from it. Inherited needles with no marking can be measured with a needle gauge.
Knitting needles
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| Metric (mm) | US | UK / Canada |
|---|---|---|
| 1.5 | 000 | — |
| 1.75 | 00 | 15 |
| 2 | 0 | 14 |
| 2.25 | 1 | 13 |
| 2.75 | 2 | 12 |
| 3 | — | 11 |
| 3.25 | 3 | 10 |
| 3.5 | 4 | — |
| 3.75 | 5 | 9 |
| 4 | 6 | 8 |
| 4.5 | 7 | 7 |
| 5 | 8 | 6 |
| 5.5 | 9 | 5 |
| 6 | 10 | 4 |
| 6.5 | 10.5 | 3 |
| 7 | — | 2 |
| 7.5 | — | 1 |
| 8 | 11 | 0 |
| 9 | 13 | 00 |
| 10 | 15 | 000 |
| 12.75 | 17 | — |
| 15 | 19 | — |
| 19 | 35 | — |
| 25 | 50 | — |
A dash means that system has no standard size at that diameter — the millimetre column is the one that always works.
Crochet hooks (aluminium / plastic)
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| Metric (mm) | US (letter) | UK / Canada |
|---|---|---|
| 2.25 | B-1 | 13 |
| 2.75 | C-2 | 12 |
| 3.25 | D-3 | 10 |
| 3.5 | E-4 | 9 |
| 3.75 | F-5 | — |
| 4 | G-6 | 8 |
| 4.5 | 7 | 7 |
| 5 | H-8 | 6 |
| 5.5 | I-9 | 5 |
| 6 | J-10 | 4 |
| 6.5 | K-10.5 | 3 |
| 8 | L-11 | 0 |
| 9 | M/N-13 | — |
| 10 | N/P-15 | — |
| 11.5 | P-16 | — |
| 15 | P/Q | — |
| 16 | Q | — |
| 19 | S | — |
US hooks carry both a letter and a number, e.g. H-8. Sizes above J vary by brand, so trust the millimetres.
Steel hooks (thread crochet)
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| Metric (mm) | US (steel) | UK / Canada |
|---|---|---|
| 0.75 | 14 | — |
| 0.85 | 13 | — |
| 1 | 12 | — |
| 1.1 | 11 | — |
| 1.3 | 10 | — |
| 1.4 | 9 | — |
| 1.5 | 8 | — |
| 1.65 | 7 | — |
| 1.8 | 6 | — |
| 1.9 | 5 | — |
| 2 | 4 | — |
| 2.1 | 3 | — |
| 2.25 | 2 | — |
| 2.75 | 1 | — |
| 3.25 | 0 | — |
| 3.5 | 00 | — |
Steel hooks are numbered the other way round: a higher number is a finer hook. They are used for crochet thread and fine lace, not yarn.
Good to know
- Millimetres are the reliable column. US and UK numbers are conventions, and the large sizes in particular vary between brands.
- A dash means that system has no standard size at that diameter — pick the nearest millimetre size instead.
- The size on the ball band is a starting point, not a rule. Change needle or hook size until your swatch matches the gauge the pattern asks for.
- Steel hooks are numbered in reverse and sized for crochet thread; they are not interchangeable with the letter-sized hooks used for yarn.
FAQ
- What size is a US 8 knitting needle in mm?
- A US 8 is 5 mm, which is a UK 6. It is one of the most common sizes for worsted / aran weight yarn.
- Why do UK needle numbers go down as the needle gets bigger?
- The old UK (and Canadian) system numbers needles by wire gauge, where a higher number meant thinner wire. US numbering does the opposite. That is why a UK 14 and a US 0 are the same 2 mm needle.
- What is an H hook?
- A US H-8 crochet hook is 5 mm. US hooks carry a letter and a number together; the letter order runs B, C, D, E, F, G, H, I, J and up as the hook gets thicker.
- Are steel crochet hook sizes the same as regular hooks?
- No — they are a separate scale for thread crochet and they run backwards. A steel 14 is 0.75 mm, far finer than a B-1 (2.25 mm) yarn hook.
- How do I measure a needle with no size printed on it?
- Slide it through the holes of a needle gauge until you find the one it passes through snugly, and read the millimetre size off the gauge. Then use this chart for the US or UK equivalent.