Ring size chart
Enter a known measurement and read the size in all four systems, or browse the full chart from size 3 to 13 in quarter increments.
Full chart in quarter sizes
Inner diameter and circumference in millimeters.
| US / CA | UK / AU | EU / ISO | JP / CN / KR | Ø mm | mm |
|---|---|---|---|---|---|
| 3 | F | 44 | 8 | 14.1 | 44.3 |
| 3¼ | G¼ | 45 | 8 | 14.3 | 44.9 |
| 3 | G | 46 | 9 | 14.5 | 45.6 |
| 3 | H¼ | 46 | 9 | 14.7 | 46.2 |
| 4 | H | 47 | 7 | 14.9 | 46.8 |
| 4¼ | H | 47 | 7 | 15.1 | 47.4 |
| 4 | I | 48 | 8 | 15.3 | 48.1 |
| 4 | I | 48 | 8 | 15.5 | 48.7 |
| 5 | J | 49 | 9 | 15.7 | 49.3 |
| 5¼ | J | 49 | 9 | 15.9 | 50 |
| 5 | K | 51 | 10 | 16.1 | 50.6 |
| 5 | K | 51 | 10 | 16.3 | 51.2 |
| 6 | L | 52 | 12 | 16.5 | 51.8 |
| 6¼ | L | 52 | 12 | 16.7 | 52.5 |
| 6 | M | 53 | 13 | 16.9 | 53.1 |
| 6 | M | 53 | 13 | 17.1 | 53.7 |
| 7 | N | 54 | 14 | 17.3 | 54.3 |
| 7¼ | N | 54 | 14 | 17.5 | 55 |
| 7 | O | 56 | 15 | 17.7 | 55.6 |
| 7 | O | 56 | 15 | 17.9 | 56.2 |
| 8 | P | 57 | 16 | 18.1 | 56.9 |
| 8¼ | P | 57 | 16 | 18.3 | 57.5 |
| 8 | Q | 58 | 17 | 18.5 | 58.1 |
| 8 | Q | 58 | 17 | 18.7 | 58.7 |
| 9 | R | 60 | 18 | 18.9 | 59.4 |
| 9¼ | R | 60 | 18 | 19.1 | 60 |
| 9 | S | 61 | 19 | 19.3 | 60.6 |
| 9 | S | 61 | 19 | 19.5 | 61.3 |
| 10 | T | 62 | 20 | 19.7 | 61.9 |
| 10¼ | T | 62 | 20 | 19.9 | 62.5 |
| 10 | U | 63 | 22 | 20.1 | 63.1 |
| 10 | U | 63 | 22 | 20.3 | 63.8 |
| 11 | V | 65 | 23 | 20.5 | 64.4 |
| 11¼ | V | 65 | 23 | 20.7 | 65 |
| 11 | W | 66 | 24 | 20.9 | 65.7 |
| 11 | W | 66 | 24 | 21.1 | 66.3 |
| 12 | X | 67 | 25 | 21.3 | 66.9 |
| 12¼ | Y¼ | 68 | 17 | 21.5 | 67.5 |
| 12 | Y | 68 | 18 | 21.7 | 68.2 |
| 12 | Z¼ | 69 | 18 | 21.9 | 68.8 |
| 13 | Z | 69 | 18 | 22.1 | 69.4 |
Conversion questions
How do I read this conversion chart?
The US/CA column is the primary reference. Diameter and circumference in millimeters are physical measurements that are identical across every system; UK letters and EU/JP numbers are standardized conversions of those measurements.
What is the difference between diameter and circumference?
Diameter is the straight-line distance between two opposite inner edges of a ring. Circumference is the full inner perimeter, equal to the diameter multiplied by π (about 3.14).
Why does my EU size sometimes differ by one number?
EU sizes round the circumference to the nearest millimeter, and different houses round differently. Always confirm against the chart of the brand you are buying from.