Ring Size Chart & Converter
Measure your finger or convert between US, UK, EU and Japanese ring sizes — with inside diameter and circumference in millimetres.
Tip: wrap a strip of paper around your finger, mark where it overlaps, measure the length in mm = circumference.
International ring size chart
| US | UK | EU | Japan | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14 | 44.2 |
| 3.5 | G | 46 | 5 | 14.4 | 45.5 |
| 4 | H | 47 | 7 | 14.8 | 46.8 |
| 4.5 | I | 48 | 8 | 15.2 | 48 |
| 5 | J½ | 49 | 9 | 15.7 | 49.3 |
| 5.5 | L | 51 | 10 | 16.1 | 50.6 |
| 6 | M | 52 | 12 | 16.5 | 51.9 |
| 6.5 | N | 53 | 13 | 16.9 | 53.1 |
| 7 | O | 54 | 14 | 17.3 | 54.4 |
| 7.5 | P | 56 | 15 | 17.7 | 55.7 |
| 8 | Q | 57 | 16 | 18.1 | 57 |
| 8.5 | Q½ | 58 | 17 | 18.5 | 58.3 |
| 9 | R½ | 59 | 18 | 19 | 59.5 |
| 9.5 | S½ | 61 | 19 | 19.4 | 60.8 |
| 10 | T½ | 62 | 20 | 19.8 | 62.1 |
| 10.5 | U½ | 63 | 22 | 20.2 | 63.4 |
| 11 | V½ | 65 | 23 | 20.6 | 64.6 |
| 11.5 | W½ | 66 | 24 | 21 | 65.9 |
| 12 | Y | 67 | 25 | 21.4 | 67.2 |
| 12.5 | Z | 68 | 26 | 21.8 | 68.5 |
| 13 | Z+1 | 70 | 27 | 22.2 | 69.7 |
FAQ
How do I measure my ring size at home?
Wrap a thin strip of paper or string around the base of your finger, mark where it overlaps, then measure that length in millimetres — that's your inside circumference. Enter it above to get your size. Measure at the end of the day when fingers are largest.
What is the most common ring size?
For women, US 6–7 is most common; for men, US 9–10. But always measure — finger size varies a lot between people and even between hands.
How does US ring size convert to UK and EU?
US uses numbers (3–13), the UK uses letters (F–Z), and the EU (ISO 8653) uses the inside circumference in millimetres. Use the chart below for the full cross-reference.
Should I size up for a wide band?
Yes — wide bands (6mm+) fit more snugly, so consider going up a quarter to a half size.