Knitting Needle Size Converter
Convert needle sizes between US, metric (mm), and UK/Canadian systems.
Quick Converter
Full Conversion Reference Table
| US Size | Metric (mm) | UK / Canadian |
|---|
Metric-Only Sizes (No US Equivalent)
| Metric (mm) | Notes |
|---|---|
| 2.5 mm | Between US 1 and 2; common in European patterns |
| 3.0 mm | Between US 2 and 3; common in European patterns |
| 3.5 mm (US 4) | Also listed as metric 3.5 in some EU patterns |
| 4.5 mm | Between US 7 and 8; used in some European patterns |
| 5.5 mm | Between US 9 and 10; common in some EU designs |
| 7.0 mm | Between US 10.5 and 11 |
| 11.0 mm | Between US 15 and 17 |
| 13.0 mm | Between US 17 and 19 |
How to Use This Converter
- Use the Quick Converter — choose a size system and select a needle size to see all equivalents instantly.
- Use the search box above the table to filter by US number, mm size, or UK number.
- Note that some US sizes share the same metric size (e.g., US 4 and US 5 are both close to 3.5–3.75mm).
Understanding Needle Size Systems
- US: Numbered 0–50. Larger numbers = larger needles.
- Metric (mm): Measures actual shaft diameter. The most accurate and internationally consistent system.
- UK/Canadian (old system): Numbered in reverse — higher numbers = smaller needles. This system is largely obsolete but still appears in vintage patterns.
- When in doubt, always use the mm measurement to match your needle correctly.
About this Knitting Needle Size Converter
Knitting needles are labeled using US numbered sizes, UK numbered sizes, and metric millimeter diameters, and the US and UK numbering systems run in opposite directions from each other — a common source of confusion when following a pattern from a different region.
Why millimeter size is the safest reference
A US size 8 needle and a UK size 8 needle are not the same diameter at all, since the two numbering systems don't align. Checking the metric millimeter measurement removes any ambiguity about which actual needle diameter a pattern intends.