US Size to UK Size
Calculate US Size to UK Size conversions for work, school, or personal projects. Our free tool provides instant results with detailed conversion data. Try it...
Based on published international size equivalence charts. · Updated 2026-05-29
Ring Size Calculator
Ring Size Conversion Chart
| US | UK | EU | Japan |
|---|---|---|---|
| 3 | F | 44 | 1 |
| 3.25 | F½ | 44.5 | 2 |
| 3.5 | G | 45 | 3 |
| 3.75 | G½ | 45.5 | 4 |
| 4 | H | 46 | 5 |
| 4.25 | H½ | 46.5 | 6 |
| 4.5 | I | 47 | 7 |
| 4.75 | I½ | 47.5 | 8 |
| 5 | J | 48 | 9 |
| 5.25 | J½ | 48.5 | 10 |
| 5.5 | K | 49 | 11 |
| 5.75 | K½ | 49.5 | 12 |
| 6 | L | 50 | 13 |
| 6.25 | L½ | 50.5 | 14 |
| 6.5 | M | 51 | 15 |
| 6.75 | M½ | 51.5 | 16 |
| 7 | N | 52 | 17 |
| 7.25 | N½ | 52.5 | 18 |
| 7.5 | O | 53 | 19 |
| 7.75 | O½ | 53.5 | 20 |
| 8 | P | 54 | 21 |
| 8.25 | P½ | 54.5 | 22 |
| 8.5 | Q | 55 | 23 |
| 8.75 | Q½ | 55.5 | 24 |
| 9 | R | 56 | 25 |
| 9.25 | R½ | 56.5 | 26 |
| 9.5 | S | 57 | 27 |
| 9.75 | S½ | 57.5 | 28 |
| 10 | T | 58 | 29 |
| 10.25 | T½ | 58.5 | 30 |
| 10.5 | U | 59 | 31 |
| 10.75 | U½ | 59.5 | 32 |
| 11 | V | 60 | 33 |
| 11.25 | V½ | 60.5 | 34 |
| 11.5 | W | 61 | 35 |
| 11.75 | W½ | 61.5 | 36 |
| 12 | X | 62 | 37 |
The formula
Sizes map through equivalence charts, not a single multiplier. Use the chart above to find the matching size.