Ring Size Conversion Chart
Use this chart to convert between U.S. finger sizes and other common systems. Inside diameter is what we use when finishing a ring — the same scale as our quote upload size suggestion.
How to measure: Take a ring that already fits the finger. Measure the inside diameter straight across the center in millimeters. Find that number in the chart, then read across for the U.S. size and other conversions.
Uploading a ring model for a quote? Our tool can suggest a size from the model when the finger hole is clear. Get a quote / upload 3D.
| US / Canada | Inside diameter (mm) | Inside circumference (mm) | UK / Australia | Europe (ISO) | Germany | Japan | Switzerland / Italy / Spain |
|---|---|---|---|---|---|---|---|
| 3 | 14.07 | 44.2 | F | 44 | 14.1 | 4 | 4.2 |
| 3¼ | 14.27 | 44.8 | F½ | 45 | 14.3 | 5 | 4.8 |
| 3½ | 14.48 | 45.5 | G | 46 | 14.5 | — | 5.5 |
| 3¾ | 14.68 | 46.1 | G½ | 46 | 14.7 | 6 | 6.1 |
| 4 | 14.88 | 46.8 | H | 47 | 14.9 | 7 | 6.8 |
| 4¼ | 15.09 | 47.4 | H½ | 47 | 15.1 | — | 7.4 |
| 4½ | 15.29 | 48.0 | I | 48 | 15.3 | 8 | 8 |
| 4¾ | 15.49 | 48.7 | J | 49 | 15.5 | — | 8.7 |
| 5 | 15.70 | 49.3 | J½ | 49 | 15.7 | 9 | 9.3 |
| 5¼ | 15.90 | 50.0 | K | 50 | 15.9 | — | 10 |
| 5½ | 16.10 | 50.6 | K½ | 51 | 16.1 | 10 | 10.6 |
| 5¾ | 16.31 | 51.2 | L | 51 | 16.3 | — | 11.2 |
| 6 | 16.51 | 51.9 | L½ | 52 | 16.5 | 11 | 11.9 |
| 6¼ | 16.71 | 52.5 | M | 52 | 16.7 | 12 | 12.5 |
| 6½ | 16.92 | 53.1 | M½ | 53 | 16.9 | 13 | 13.1 |
| 6¾ | 17.12 | 53.8 | N | 54 | 17.1 | — | 13.8 |
| 7 | 17.32 | 54.4 | N½ | 54 | 17.3 | 14 | 14.4 |
| 7¼ | 17.53 | 55.1 | O | 55 | 17.5 | — | 15.1 |
| 7½ | 17.73 | 55.7 | O½ | 56 | 17.7 | 15 | 15.7 |
| 7¾ | 17.93 | 56.3 | P | 56 | 17.9 | — | 16.3 |
| 8 | 18.14 | 57.0 | P½ | 57 | 18.1 | 16 | 17 |
| 8¼ | 18.34 | 57.6 | Q | 58 | 18.3 | — | 17.6 |
| 8½ | 18.54 | 58.3 | Q½ | 58 | 18.5 | 17 | 18.3 |
| 8¾ | 18.75 | 58.9 | R | 59 | 18.8 | — | 18.9 |
| 9 | 18.95 | 59.5 | R½ | 60 | 18.9 | 18 | 19.5 |
| 9¼ | 19.15 | 60.2 | S | 60 | 19.1 | — | 20.2 |
| 9½ | 19.35 | 60.8 | S½ | 61 | 19.4 | 19 | 20.8 |
| 9¾ | 19.56 | 61.4 | T | 61 | 19.6 | — | 21.4 |
| 10 | 19.76 | 62.1 | T½ | 62 | 19.8 | 20 | 22.1 |
| 10¼ | 19.96 | 62.7 | U | 63 | 20.0 | 21 | 22.7 |
| 10½ | 20.17 | 63.4 | U½ | 63 | 20.2 | 22 | 23.4 |
| 10¾ | 20.37 | 64.0 | V | 64 | 20.4 | — | 24 |
| 11 | 20.57 | 64.6 | V½ | 65 | 20.6 | 23 | 24.6 |
| 11¼ | 20.78 | 65.3 | W | 65 | 20.8 | — | 25.3 |
| 11½ | 20.98 | 65.9 | W½ | 66 | 21.0 | 24 | 25.9 |
| 11¾ | 21.18 | 66.6 | X | 67 | 21.2 | — | 26.6 |
| 12 | 21.39 | 67.2 | X½ | 67 | 21.4 | 25 | 27.2 |
| 12¼ | 21.59 | 67.8 | Y | 68 | 21.6 | — | 27.8 |
| 12½ | 21.79 | 68.5 | Z | 68 | 21.8 | 26 | 28.5 |
| 12¾ | 22.00 | 69.1 | Z½ | 69 | 22.0 | — | 29.1 |
| 13 | 22.20 | 69.7 | Z1 | 70 | 22.2 | 27 | 29.7 |
Sizes shown are approximate. Manufacturers can vary slightly. For a finished ring, confirm the size with a ring stick or a ring that already fits. Diameter and circumference follow the standard U.S. relationship used on this site (inside diameter ≈ 0.8128 × U.S. size + 11.63 mm).
