Ring Size Converter
Ring Size Converter
Convert ring sizes between US, UK, EU, French & Japanese systems
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Ring Size Converter: US, UK, EU, French & Japanese Sizing
Ring sizes don't match across countries. A US 7 is a UK N, an EU 54 and a Japanese 13 — the same ring, four labels. If you're buying a ring from an international seller (or as a surprise gift), converting first is the only way to avoid a ring that won't fit. This tool maps your size across every major system, anchored to the ring's actual inner circumference in millimetres.
Example: US 7 = UK N = EU 54 = JP 13 (inner circumference ≈ 54.4 mm).
How Ring Sizing Works
Every ring size is really one physical measurement: the inner circumference of the band (or its diameter, which is the distance straight across the inside). Countries just label that measurement differently — the US and Japan use numbers, the UK uses letters, and the EU uses the circumference in millimetres rounded to the nearest whole number.
If you don't know any size, measure a ring that already fits: take the inside diameter in millimetres and use the "I know the circumference" tab above (circumference ≈ diameter × 3.14).
Quick Reference Table
| US | UK | EU | Japan | Circumference |
|---|---|---|---|---|
| 5 | J | 49 | 9 | 49.3 mm |
| 6 | L | 52 | 11 | 51.9 mm |
| 7 | N | 54 | 13 | 54.4 mm |
| 8 | P | 57 | 16 | 57.0 mm |
| 9 | R | 59 | 18 | 59.5 mm |
| 10 | T | 62 | 20 | 62.1 mm |
Tips for Measuring (and Buying a Surprise)
- Measure at the end of the day — fingers swell slightly and you want the larger fit.
- For a surprise gift, borrow a ring they already wear and measure its inside diameter, then convert.
- A band wider than ~6 mm fits tighter — consider going up a half size.
- UK letters can fall between US half-sizes; this converter picks the closest standard letter and shows the exact mm so you can judge the fit.