Ring size chart
Every ring-sizing system is a different way of writing one number: the inside of the ring. Give us that number in any form.
Brands vary. These conversions follow the ISO 8653 circumference definition and the standard US diameter formula; UK letters and Japanese numbers are accurate to about half a size between jewellers. Another label can run half a size (or a whole size) different, so if the store publishes its own chart, trust that first. All sources
Ring size conversion chart
| US | UK / AU | EU / ISO | FR / IT | Japan | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|---|
| 2.9999999999999996 | F | 44 | 4 | 4 | 14.1 | 44.2 |
| 3.499999999999999 | G | 45 | 5 | 5 | 14.5 | 45.5 |
| 3.999999999999999 | H | 47 | 7 | 7 | 14.9 | 46.8 |
| 4.500000000000001 | I | 48 | 8 | 8 | 15.3 | 48.0 |
| 4.999999999999998 | J | 49 | 9 | 9 | 15.7 | 49.3 |
| 5.5 | K | 51 | 11 | 10 | 16.1 | 50.6 |
| 5.999999999999997 | L | 52 | 12 | 12 | 16.5 | 51.9 |
| 6.499999999999999 | M½ | 53 | 13 | 13 | 16.9 | 53.1 |
| 7.000000000000001 | N½ | 54 | 14 | 14 | 17.3 | 54.4 |
| 7.499999999999998 | O½ | 56 | 16 | 15 | 17.7 | 55.7 |
| 8 | P½ | 57 | 17 | 16 | 18.1 | 57.0 |
| 8.500000000000002 | Q½ | 58 | 18 | 18 | 18.5 | 58.2 |
| 9 | R½ | 60 | 20 | 19 | 18.9 | 59.5 |
| 9.500000000000002 | S½ | 61 | 21 | 20 | 19.4 | 60.8 |
| 10.000000000000004 | T½ | 62 | 22 | 21 | 19.8 | 62.1 |
| 10.5 | U½ | 63 | 23 | 22 | 20.2 | 63.3 |
| 10.999999999999998 | V½ | 65 | 25 | 24 | 20.6 | 64.6 |
| 11.499999999999995 | W½ | 66 | 26 | 25 | 21.0 | 65.9 |
| 12.000000000000002 | X½ | 67 | 27 | 26 | 21.4 | 67.2 |
| 12.499999999999998 | Y½ | 68 | 28 | 27 | 21.8 | 68.5 |
| 13 | Z½ | 70 | 30 | 29 | 22.2 | 69.7 |
Questions shoppers ask
How do I find my ring size at home?
Wrap a strip of paper around the base of your finger, mark where it overlaps and measure the length in millimetres: that is your ISO/EU ring size. Or measure the inside diameter of a ring that fits and use the diameter option above.
What is a US ring size 7 in EU?
A US 7 has an inside diameter of about 17.3 mm and a circumference of about 54.4 mm, so it is an EU/ISO 54 and a UK N½.
How does ISO 8653 define ring size?
ISO 8653 sizes a ring by its inside circumference in millimetres. A size 54 ring measures 54 mm around the inside. France, Italy and Switzerland use the same measurement minus 40.
When is the best time to measure?
At the end of the day, when your hands are warm. Fingers shrink in the cold and swell in heat, so a size measured on a cold morning can come out half a size small. Wide bands need about half a size more room.