Ring size chart
Ring size is defined internationally as the inside circumference of the ring in millimetres. Every other system is a label on top of that measurement, which is why this chart leads with millimetres.
| US / Canada | Inside diameter (mm) | Inside circumference (mm) | UK / AU | EU | JP / IN |
|---|---|---|---|---|---|
| 3 | 14.07 | 44.20 | F | 44 | 4 |
| 3½ | 14.47 | 45.46 | G | 45 | 5 |
| 4 | 14.88 | 46.75 | H | 47 | 6 |
| 4½ | 15.29 | 48.03 | I | 48 | 7 |
| 5 | 15.69 | 49.29 | J½ | 49 | 9 |
| 5½ | 16.10 | 50.58 | K½ | 51 | 10 |
| 6 | 16.51 | 51.87 | L½ | 52 | 11 |
| 6½ | 16.91 | 53.12 | M½ | 53 | 12 |
| 7 | 17.32 | 54.41 | N½ | 54 | 13 |
| 7½ | 17.73 | 55.70 | O½ | 56 | 15 |
| 8 | 18.13 | 56.96 | P½ | 57 | 16 |
| 8½ | 18.54 | 58.25 | Q½ | 58 | 17 |
| 9 | 18.95 | 59.53 | R½ | 60 | 18 |
| 9½ | 19.35 | 60.79 | S½ | 61 | 19 |
| 10 | 19.76 | 62.08 | T½ | 62 | 20 |
| 10½ | 20.16 | 63.33 | U½ | 63 | 22 |
| 11 | 20.57 | 64.62 | V½ | 65 | 23 |
| 11½ | 20.98 | 65.91 | W½ | 66 | 24 |
| 12 | 21.38 | 67.17 | Y | 67 | 25 |
| 12½ | 21.79 | 68.46 | Z | 68 | 26 |
| 13 | 22.20 | 69.74 | Z+1 | 70 | 27 |
| 13½ | 22.60 | 71.00 | Z+2 | 71 | 28 |
| 14 | 23.01 | 72.29 | Z+3 | 72 | 29 |
| 14½ | 23.42 | 73.58 | Z+4 | 74 | 30 |
| 15 | 23.82 | 74.83 | Z+5 | 75 | 31 |
About this data
inside_diameter_mm = 11.63 + (0.8128 x us_size); circumference = pi x diameter
Verification status: requires verification. The international equivalents below are conventional published mappings and have not been independently audited by this project.
- US 9 and US 10 differ from the recorded GIA anchor by approximately 0.05 mm of inside diameter.
- UK letter equivalents vary between published charts at half-letter boundaries.
- Japanese and Indian numeric systems are commonly treated as equivalent; some retailers disagree at the extremes.
Data version sizing-standard-1.0.0. The measurement flow, the converter and this chart all read from this one dataset.