Find your ring size across US, UK, EU, and Japanese systems, or convert from millimeter measurements. Whether you are buying an engagement ring online or need to know your partner\'s size, this converter gives you instant results with three input methods: by size number, by millimeter circumference, or from a string measurement. No signup, no email required.
Measure in the afternoon when fingers are at their largest. Finger size changes with temperature and time of day.
| US | UK | EU | JP | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.0 | 44.0 |
| 3.5 | G | 45.5 | 5 | 14.4 | 45.2 |
| 4 | H | 46.5 | 7 | 14.8 | 46.5 |
| 4.5 | I | 47.8 | 8 | 15.2 | 47.8 |
| 5 | J | 49 | 9 | 15.6 | 49.0 |
| 5.5 | K | 50.3 | 10 | 15.9 | 50.3 |
| 6 | L | 51.5 | 12 | 16.5 | 51.8 |
| 6.5 | M | 52.8 | 13 | 16.9 | 53.1 |
| 7 | N | 54 | 14 | 17.3 | 54.3 |
| 7.5 | O | 55.3 | 15 | 17.7 | 55.6 |
| 8 | P | 56.6 | 16 | 18.1 | 56.9 |
| 8.5 | Q | 57.8 | 17 | 18.5 | 58.1 |
| 9 | R | 59 | 18 | 18.9 | 59.3 |
| 9.5 | S | 60.3 | 19 | 19.2 | 60.6 |
| 10 | T | 61.6 | 20 | 19.8 | 62.1 |
| 10.5 | U | 62.8 | 22 | 20.2 | 63.4 |
| 11 | V | 64 | 23 | 20.6 | 64.6 |
| 12 | X | 66.6 | 25 | 21.3 | 66.9 |
| 13 | Z | 69.1 | 27 | 22.0 | 69.1 |
Place a ring that fits well on a ruler. Measure the inside diameter in millimeters.
Wrap a strip of paper or string snugly around your finger. Mark where it overlaps, then measure the length in mm.
Print our ring sizer at 100% scale. Place your ring on the circles until you find the best match.
Tiffany & Co. uses US sizing. Their rings tend to run true to standard US sizes.
Pandora uses their own internal numbering. Always check their size guide separately.
Wide bands (6mm+) typically need half a size larger than your measured size for comfortable fit.
Wrap a thin strip of paper or string around the base of your finger. Mark where it overlaps, then measure the length in millimeters. This gives you the circumference, which you can enter directly into our converter. For the most accurate result, measure three times and take the average.
Always round up to the larger size. A ring that is slightly loose is far more comfortable than one that is tight. You can also ask a jeweler about comfort-fit bands, which feel slightly larger than standard bands of the same size.
The UK adopted an alphabetical system (A through Z) in the early 20th century. Each letter corresponds to a specific inner circumference. This system is also used in Australia, Ireland, and South Africa. The US system uses numbers, which makes half-sizes easier to express.
Yes. Fingers swell in heat, after exercise, and in the afternoon. They shrink in cold weather and in the morning. For the best measurement, check your size in the afternoon at room temperature. Avoid measuring after exercise or hot showers.
Yes, approximately. EU ring sizes correspond to the inner circumference of the ring in millimeters, rounded to the nearest whole number. So EU 54 means approximately 54mm circumference.