Conversion chart
Knitting needle sizes, compared by diameter.
Use the millimeter diameter as the dependable reference. US number labels are common conventions, and the pattern gauge still determines the needle that produces the right fabric in your hands.
Metric diameter is the reliable comparison. Letter and number labels can vary by manufacturer.
Source-backed reference
Metric to US knitting needle chart
This quick-reference range covers commonly used diameters. The full CYC table extends from 1.5 mm through 35 mm.
| Metric | US label | Guide |
|---|---|---|
| 2 mm | 0 | Open |
| 2.5 mm | No single CYC US label | Open |
| 3 mm | No single CYC US label | Open |
| 3.25 mm | 3 | Open |
| 3.5 mm | 4 | Open |
| 3.75 mm | 5 | Open |
| 4 mm | 6 | Open |
| 4.5 mm | 7 | Open |
| 5 mm | 8 | Open |
| 5.5 mm | 9 | Open |
| 6 mm | 10 | Open |
| 6.5 mm | 10½ | Open |
| 8 mm | 11 | Open |
| 10 mm | 15 | Open |
Need a stitch count?
Convert your measured swatch into project stitches and rows.
The gauge calculator uses your own swatch instead of assuming a universal tension for a needle size.
Open knitting gauge calculatorSource notes
Last reviewed September 1, 2026
- Craft Yarn Council: Hooks & Needles Metric and US hook and needle size tables; gauge-swatch qualification.
- Craft Yarn Council: Standard Yarn Weight System Yarn weight categories, common names, gauge ranges, and tool ranges.