Ring size conversion
UK ring size X½ in US and European sizes
UK ring size X½ is US size 12 and European (ISO) size 67.5. The inside diameter is 21.49 mm and the circumference 67.51 mm.
Checking it yourself
Measure straight across the inside of a ring that already fits. About 21.49 mm means UK X½. Or wrap paper around the finger and measure the length — about 67.51 mm is the same size.
The UK, Ireland and Australia share this letter system, sometimes called the Wheat Sheaf scale. The US uses numbers, and Europe uses the circumference in millimetres directly, which is why the European size and the circumference above are the same figure.
Full conversion chart
| UK / AU | US | Europe | India / Japan | Diameter |
|---|---|---|---|---|
| F | 3 | 44.1 | 4 | 14.05 mm |
| F½ | 3.25 | 44.8 | — | 14.25 mm |
| G | 3.5 | 45.4 | 5 | 14.45 mm |
| G½ | 3.75 | 46 | — | 14.65 mm |
| H | 4 | 46.7 | 6 | 14.86 mm |
| H½ | 4.25 | 47.3 | — | 15.06 mm |
| I | 4.5 | 48 | 7 | 15.27 mm |
| J | 4.75 | 48.6 | 8 | 15.47 mm |
| J½ | 5 | 49.3 | 9 | 15.7 mm |
| K | 5.25 | 50 | — | 15.9 mm |
| K½ | 5.5 | 50.6 | 10 | 16.1 mm |
| L | 5.75 | 51.2 | — | 16.3 mm |
| L½ | 6 | 51.9 | 11 | 16.51 mm |
| M | 6.25 | 52.5 | — | 16.71 mm |
| M½ | 6.5 | 53.2 | 12 | 16.92 mm |
| N | 6.75 | 53.8 | 13 | 17.13 mm |
| N½ | 7 | 54.5 | 14 | 17.35 mm |
| O | 7.25 | 55.1 | — | 17.55 mm |
| O½ | 7.5 | 55.8 | 15 | 17.75 mm |
| P | 7.75 | 56.5 | — | 17.97 mm |
| P½ | 8 | 57.1 | 16 | 18.19 mm |
| Q | 8.25 | 57.8 | — | 18.39 mm |
| Q½ | 8.5 | 58.2 | 17 | 18.53 mm |
| R | 8.75 | 59.1 | — | 18.8 mm |
| R½ | 9 | 59.5 | 18 | 18.95 mm |
| S | 9.25 | 60.4 | — | 19.22 mm |
| S½ | 9.5 | 61 | 19 | 19.41 mm |
| T | 9.75 | 61.6 | — | 19.62 mm |
| T½ | 10 | 62.3 | 20 | 19.84 mm |
| U | 10.25 | 62.9 | — | 20.02 mm |
| U½ | 10.5 | 63.5 | 22 | 20.2 mm |
| V | 10.75 | 64.2 | — | 20.44 mm |
| V½ | 11 | 65 | 23 | 20.68 mm |
| W½ | 11.5 | 66.2 | 24 | 21.08 mm |
| X½ | 12 | 67.5 | 25 | 21.49 mm |
| Y½ | 12.5 | 68.8 | 26 | 21.89 mm |
| Z½ | 13 | 70.2 | 27 | 22.33 mm |
Measure it on your screen
Lay a ring against circles drawn true to life, calibrated with any bank card.
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