Tools & techniques
Knitting Needle Conversion Chart: US, Metric & Old UK
Use the millimeter diameter as the common measurement when a pattern and your tool use different sizing systems. The numbers are labels, not a scale you can convert by multiplying. A size conversion identifies a tool; it does not guarantee the pattern's gauge.
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Find the size you need
For example, US 8 is 5 mm and old UK 6. Modern UK patterns usually use millimeters; the old UK column is useful for vintage patterns. A dash means our reference has no listed equivalent.
| Metric diameter | US size | Old UK size |
|---|---|---|
| 1.5 mm | 000 | — |
| 1.75 mm | 00 | — |
| 2 mm | 0 | 14 |
| 2.25 mm | 1 | 13 |
| 2.5 mm | — | — |
| 2.75 mm | 2 | 12 |
| 3 mm | — | 11 |
| 3.25 mm | 3 | 10 |
| 3.5 mm | 4 | — |
| 3.75 mm | 5 | 9 |
| 4 mm | 6 | 8 |
| 4.5 mm | 7 | 7 |
| 5 mm | 8 | 6 |
| 5.5 mm | 9 | 5 |
| 6 mm | 10 | 4 |
| 6.5 mm | 10½ | 3 |
| 7 mm | — | 2 |
| 7.5 mm | — | 1 |
| 8 mm | 11 | 0 |
| 9 mm | 13 | 00 |
| 10 mm | 15 | 000 |
| 12.75 mm | 17 | — |
| 15 mm | 19 | — |
| 19 mm | 35 | — |
| 25 mm | 50 | — |
| 35 mm | 70 | — |
Prefer selecting a size? Use the interactive size converter to highlight its equivalents.
Save or print the chart
Check an unmarked needle
- Use a needle gauge with holes labeled in millimeters.
- Slide the straight shaft into a hole without forcing it. The correct hole fits closely; the tapered tip alone can fit a hole that is too small.
- For a circular needle, measure the tip shaft rather than its cable. Check both tips if they may have been mixed.
Size is different from length and material
Diameter controls the size of the loops, but your tension, yarn and technique determine the finished gauge. A circular needle's advertised length normally includes both tips and the cable. The diameter conversion here says nothing about that length or whether the needle will fit a small tube.
Common conversion questions
Questions
What size is US 8 in millimeters?
US 8 is 5 mm in this chart, also old UK 6.
Are UK and US needle numbers the same?
No. Old UK numbers generally decrease as diameter increases; US numbers generally increase. Modern UK patterns usually give millimeters.
Why is there no US size for some metric needles?
The systems do not have an equivalent for every diameter. Use the millimeter marking instead of guessing an adjacent number.
Reference sizes: Craft Yarn Council Hooks & Needles. Old UK sizes follow the existing converter's reference; check the manufacturer's millimeter marking when working from vintage labels.
