Knitting needle sizes
Knitting needle size chart.
US, UK and metric side by side, with the yarn weight each size suits and the gauge you can expect from it. Where a size has no equivalent in another system, the chart says so instead of guessing.
| Metric | US | UK / CA | Yarn weight | Typical gauge |
|---|---|---|---|---|
| 2.0 mm | 0 | 14 | Lace / 0 | 8–9 sts/in |
| 2.25 mm | 1 | 13 | Super fine / 1 | 7–8 sts/in |
| 2.75 mm | 2 | 12 | Super fine / 1 | 7–8 sts/in |
| 3.0 mm | — | 11 | Super fine / 1 | 7 sts/in |
| 3.25 mm | 3 | 10 | Fine / 2 | 6–7 sts/in |
| 3.5 mm | 4 | — | Fine / 2 | 6–7 sts/in |
| 3.75 mm | 5 | 9 | Light / DK / 3 | 5.5–6 sts/in |
| 4.0 mm | 6 | 8 | Light / DK / 3 | 5.5 sts/in |
| 4.5 mm | 7 | 7 | Medium / 4 | 5 sts/in |
| 5.0 mm | 8 | 6 | Medium / 4 | 4.5–5 sts/in |
| 5.5 mm | 9 | 5 | Medium / 4 | 4–4.5 sts/in |
| 6.0 mm | 10 | 4 | Medium–bulky | 4 sts/in |
| 6.5 mm | 10½ | 3 | Bulky / 5 | 3.5 sts/in |
| 7.0 mm | — | 2 | Bulky / 5 | 3.25 sts/in |
| 7.5 mm | — | 1 | Bulky / 5 | 3 sts/in |
| 8.0 mm | 11 | 0 | Bulky / 5 | 3 sts/in |
| 9.0 mm | 13 | 00 | Super bulky / 6 | 2.5 sts/in |
| 10.0 mm | 15 | 000 | Super bulky / 6 | 2–2.5 sts/in |
| 12.0 mm | 17 | — | Super bulky / 6 | 1.75 sts/in |
| 15.0 mm | 19 | — | Jumbo / 7 | 1.5 sts/in |
| 19.0 mm | 35 | — | Jumbo / 7 | 1.25 sts/in |
| 25.0 mm | 50 | — | Jumbo / 7 | 0.75 sts/in |
Gauge figures are for stockinette at the stated yarn weight and are a starting point for swatching, not a promise — measure your own. Where a cell reads “—”, that size has no standard counterpart in that system.
Trust the millimetres.
Of the three numbers on this chart, only one is a measurement. US and UK sizes are conventions — and they run in opposite directions, which is why converting from memory goes wrong so reliably. A UK 8 is a US 6. A UK 6 is a US 8. If a pattern gives you millimetres, use the millimetres and ignore the rest.
Needle questions
Asked constantly, answered once.
- What is US size 8 in mm?
- US 8 is 5.0 mm, and UK 6. It is the most common needle in a knitter’s kit because it is the size worsted-weight yarn is usually written for.
- Why do UK needle sizes run backwards?
- Because the UK numbering descends from a wire gauge, where a higher number meant thinner wire. US sizes were assigned the intuitive way round — bigger number, bigger needle. The two systems disagree in direction, which is exactly why converting from memory goes wrong so often. Metric is the only one of the three that states a physical measurement, so when a pattern gives millimetres, trust the millimetres.
- Why do some sizes have no US or UK equivalent?
- Because the systems were never designed to map onto each other. 3.0 mm and 7.0 mm are stocked in the UK and have no standard US number; 3.5 mm is a US 4 with no UK counterpart. Charts that fill those cells in are guessing. This one leaves them blank.
- What needle size should I use for my yarn?
- The yarn band’s recommendation is a starting point, not an answer — it is the size that gives the band’s stated gauge in the hands of whoever tested it. Swatch at that size, measure, and move up or down until your gauge matches the pattern. The needle size is a means; the gauge is the goal.
- Are crochet hooks sized the same way?
- The millimetres are the same physical measurement, but the letter system is different — a 5.0 mm hook is an H-8, not a size 8. The US/UK crochet converter has the full hook table alongside the stitch-name translations.
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