The circumference and diameter in millimeters (mm) along with the matching ring size, ranging from A to Z (smallest to largest), are displayed in the UK Ring Size Chart below.
Before buying the ring, use a measuring tape to determine the circumference of the desired finger. After measuring the circumference of the finger, divide the result by 3.14 to determine the diameter. Next, compare the diameter to the ring size specified in the Ring Size column.
Important Tip: If your ring size falls between two readings, choose the bigger size for a better fit.
UK Ring Size Chart in mm
| Ring Size | Circumference (mm) | Diameter (mm) |
| A | 37.8 | 12.04 |
| B | 39.1 | 12.45 |
| C | 40.4 | 12.85 |
| D | 41.7 | 13.26 |
| E | 42.9 | 13.67 |
| F | 44.2 | 14.07 |
| G | 45.5 | 14.48 |
| H | 46.8 | 14.88 |
| I | 48.0 | 15.29 |
| J | 48.7 | 15.49 |
| K | 50.0 | 15.9 |
| L | 51.2 | 16.31 |
| M | 52.5 | 16.71 |
| N | 53.8 | 17.12 |
| O | 55.1 | 17.53 |
| P | 56.3 | 17.93 |
| Q | 57.6 | 18.34 |
| R | 58.9 | 18.75 |
| S | 60.2 | 19.15 |
| T | 61.4 | 19.56 |
| U | 62.7 | 19.96 |
| V | 64.0 | 20.37 |
| W | 65.3 | 20.78 |
| X | 66.6 | 21.18 |
| Y | 67.8 | 21.59 |
| Z | 68.5 | 21.79 |