Ring size chart
| Circumference (mm) | Diameter (mm) | US | UK | EU |
|---|---|---|---|---|
| 44.2 | 14.1 | 3 | F | 44 |
| 46.8 | 14.9 | 4 | H | 47 |
| 49.3 | 15.7 | 5 | J½ | 49 |
| 51.9 | 16.5 | 6 | L½ | 52 |
| 54.4 | 17.3 | 7 | N½ | 54 |
| 57.0 | 18.1 | 8 | P½ | 57 |
| 59.5 | 18.9 | 9 | R½ | 59 |
| 62.1 | 19.8 | 10 | T½ | 62 |
| 64.6 | 20.6 | 11 | V½ | 65 |
| 67.2 | 21.4 | 12 | X½ | 67 |
Fingers swell. They are largest in the late afternoon and in warm weather, and smallest first thing on a cold morning: the difference can be a full half size. Measure warm and late, and if the knuckle is noticeably larger than the base of the finger, size to slide over the knuckle rather than to fit the base snugly.
Ring size is set by the inside circumference of the band. A 54 mm circumference is a US 6.8, a UK N and an EU 54 — the European scale is simply the circumference in millimetres, which makes it the easiest to reason about. US sizes step in quarters, so 6.8 is bought as a 6¾ or a 7; a full 7 measures 54.4 mm.
How to measure ring size
The four scales are unrelated systems rather than conversions of each other, which is why the numbers look arbitrary. EU sizing is the circumference in millimetres. Japan uses its own numeric scale. US sizes step in quarters from a base, and UK sizes use letters with half sizes between them. Only the physical measurement is common to all four, which is why every reliable conversion starts by measuring in millimetres rather than translating between the scales directly.
What people use it for
- Buying a ring online from another country
- Converting a size you were given abroad
- Measuring for a surprise gift
- Checking an existing ring against a chart
Questions
Wrap paper around the finger base, mark the overlap, and measure the length in millimetres. That is the circumference.
About N½. A US 7 is 54.4 mm circumference, which is an EU 54.
Late in the day and when warm. Fingers can vary by half a size between morning and evening.
Size so the ring passes the knuckle, then consider having it fitted with sizing beads so it does not spin.
It should slide on with slight resistance and take a little effort to remove. Too loose is how rings get lost.