Needle Size Calculator — Metric, US & Old UK Conversion
Convert between metric (mm), US, and old UK knitting needle size systems.
Select needle size in millimetres
How We Calculate This
This converter uses the standard international needle size equivalency table. Select a metric size to see the equivalent US and old UK sizes.
Key conversions
- 2mm = US 0 = Old UK 14
- 4mm = US 6 = Old UK 8
- 5mm = US 8 = Old UK 6
- 6mm = US 10 = Old UK 4
- 8mm = US 11 = Old UK 0
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates based on standard yarn weights and gauge. Results may vary with individual tension, yarn brand, and needle size.