Knitting · needle sizes
Knitting needle size conversion.
Millimetre to US needle size, from the Craft Yarn Council chart. Need a quick lookup for any size? Use the yarn yardage calculator.
mm to US knitting needle size
| Metric (mm) | US size |
|---|---|
| 1.5 mm | 000 |
| 1.75 mm | 00 |
| 2 mm | 0 |
| 2.25 mm | 1 |
| 2.75 mm | 2 |
| 3 mm | no US size listed |
| 3.125 mm | 3 |
| 3.25 mm | 3 |
| 3.5 mm | 4 |
| 3.75 mm | 5 |
| 4 mm | 6 |
| 4.25 mm | 6 |
| 4.5 mm | 7 |
| 5 mm | 8 |
| 5.25 mm | 9 |
| 5.5 mm | 9 |
| 5.75 mm | 10 |
| 6 mm | 10 |
| 6.5 mm | 10 1/2 |
| 7 mm | no US size listed |
| 8 mm | 11 |
| 9 mm | 13 |
| 10 mm | 15 |
| 12.5 mm | 17 |
| 12.75 mm | 17 |
| 15 mm | 19 |
| 19 mm | 35 |
| 25 mm | 50 |
| 35 mm | 70 |
The CYC lists no US size for 3 mm and 7 mm. Sizes such as 3.25 mm and 3.125 mm both map to US 3 on the chart. Always rely on the millimetre size printed on the needle, because US numbers vary from company to company. UK, Canadian and Japanese needle numbers are different systems and are not in the CYC chart, so they are not shown here. Source: Craft Yarn Council, Hooks & Needles, read 2026-10-02. Also see the crochet hook chart and yarn weight chart.
Frequently asked questions
What US needle size is 4 mm?
4 mm is a US size 6 on the Craft Yarn Council chart, and 4.25 mm is also listed as US 6. 3.75 mm is US 5 and 4.5 mm is US 7.
What mm is a US size 8 knitting needle?
US 8 is 5 mm on the Craft Yarn Council chart. US 9 is 5.25 or 5.5 mm, and US 7 is 4.5 mm.
Why do some sizes have no US number?
The CYC chart leaves the US column blank for 3 mm and 7 mm needles: those sizes are sold by millimetre without an agreed US number. Use the mm size.
Do I need the exact needle size from the pattern?
No. Needle size is a starting point; the gauge matters. The CYC says to knit a gauge swatch: if it is larger than the pattern gauge, go down a needle size, and if it is smaller, go up.