Every ring size system in one chart. Find your size in one column and read across for the others. Diameters follow the ISO 8653 standard used by jewellers worldwide.
| US / Canada | UK / Australia | EU / ISO | India / Japan | Diameter (mm) | Diameter (in) | Circumference (mm) |
|---|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 | 0.56 | 44.3 |
| 3.5 | G | 46 | 6 | 14.5 | 0.57 | 45.6 |
| 4 | H | 47 | 7 | 14.9 | 0.59 | 46.8 |
| 4.5 | I | 48 | 8 | 15.3 | 0.60 | 48.1 |
| 5 | J½ | 49 | 9 | 15.7 | 0.62 | 49.3 |
| 5.5 | K½ | 51 | 10 | 16.1 | 0.63 | 50.6 |
| 6 | L½ | 52 | 12 | 16.5 | 0.65 | 51.8 |
| 6.5 | M½ | 53 | 13 | 16.9 | 0.67 | 53.1 |
| 7 | N½ | 54 | 14 | 17.3 | 0.68 | 54.3 |
| 7.5 | O½ | 56 | 15 | 17.7 | 0.70 | 55.6 |
| 8 | P½ | 57 | 16 | 18.1 | 0.71 | 56.9 |
| 8.5 | Q½ | 58 | 18 | 18.5 | 0.73 | 58.1 |
| 9 | R½ | 60 | 19 | 19.0 | 0.75 | 59.7 |
| 9.5 | S½ | 61 | 20 | 19.4 | 0.76 | 60.9 |
| 10 | T½ | 62 | 21 | 19.8 | 0.78 | 62.2 |
| 10.5 | U½ | 63 | 23 | 20.2 | 0.80 | 63.5 |
| 11 | V½ | 65 | 24 | 20.6 | 0.81 | 64.7 |
| 11.5 | W½ | 66 | 25 | 21.0 | 0.83 | 66.0 |
| 12 | X½ | 67 | 26 | 21.4 | 0.84 | 67.2 |
| 12.5 | Z | 68 | 27 | 21.8 | 0.86 | 68.5 |
| 13 | Z+1 | 70 | 29 | 22.2 | 0.87 | 69.7 |
| 13.5 | Z+2 | 71 | 30 | 22.6 | 0.89 | 71.0 |
| 14 | Z+3 | 72 | 31 | 23.0 | 0.91 | 72.3 |
| 14.5 | Z+4 | 74 | 32 | 23.4 | 0.92 | 73.5 |
| 15 | Z+5 | 75 | 33 | 23.8 | 0.94 | 74.8 |
How to use this chart
- You know your US size: read across for UK, EU and India.
- You have a ring: measure its inner diameter in mm with a ruler or vernier and find the nearest value in the diameter column, or match it on screen for a faster result.
- You measured your finger with string: use the circumference column.
How the size systems differ
- US / Canada / Mexico: numbers 3–15 in half steps; each full size is 0.8 mm of diameter.
- UK / Australia / NZ / Ireland / South Africa: letters A–Z with half sizes; each letter is about 0.4 mm.
- EU / ISO / Germany / France: the inner circumference in mm, so size 54 is 54 mm around.
- India / Japan / China: numbers starting at 1 for 13 mm, rising one number per 1/3 mm.
- Switzerland: circumference minus 40, so EU 54 is Swiss 14.
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Frequently asked questions
What is ring size 6 in mm?
US size 6 is 16.5 mm inner diameter (51.9 mm circumference), UK L½, EU 52.
What is ring size 8 in mm?
US size 8 is 18.1 mm inner diameter (57.0 mm circumference), UK P½, EU 57.
What is a 17 mm ring size?
A 17 mm inner diameter is between US 6.5 (16.9 mm) and 7 (17.3 mm); most people choose US 7 / UK N½.
How do I convert UK ring size to US?
Use the chart: UK L½ is US 6, UK N½ is US 7, UK P½ is US 8, UK R½ is US 9, UK T½ is US 10.