Take a piece of non-stretchable string, ribbon, thread, or a thin strip of paper. Wrap it comfortably around your ring finger, close to the knuckle.
With a pen, carefully mark the spot where the string overlaps. For accuracy, make the marks small.
Unwrap your marked length. With a ruler, measure it in millimeters. Find your measurement below.
| Standard (US) Size | Internal Diameter | European Size |
|---|---|---|
| 3 | 14.0 mm | - |
| 3.5 | 14.4 mm | 46 |
| 4 | 14.8 mm | 47 |
| 4.5 | 15.2 mm | 48 |
| 5 | 15.6 mm | 50 |
| 5.5 | 16.0 mm | 51 |
| 6 | 16.45 mm | 52 |
| 6.5 | 16.9 mm | 53 |
| 7 | 17.3 mm | 54 |
| 7.5 | 17.7 mm | 56 |
| 8 | 18.2 mm | 57 |
| 8.5 | 18.6 mm | 58 |
| 9 | 19.0 mm | 60 |
| 9.5 | 19.4 mm | 61 |
| 10 | 19.8 mm | 62 |
| 10.5 | 20.2 mm | 64 |
| 11 | 20.6 mm | 65 |
| 11.5 | 21.0 mm | 66 |
| 12 | 21.4 mm | 67 |
| 12.5 | 21.8 mm | 69 |
| 13 | 22.2 mm | 70 |
| 13.5 | 22.6 mm | 71 |