American jewelers use numbers for ring sizes, while the UK (and Australia) use letters. So a US size 7 isn't "7" in Britain — it's roughly an N½. Here's how to convert, with a quick chart and examples.
US to UK ring size chart
| US / Canada | UK / Australia | Diameter (mm) |
|---|---|---|
| 5 | J½ | 15.7 |
| 5.5 | K½ | 16.1 |
| 6 | L½ | 16.5 |
| 6.5 | M½ | 16.9 |
| 7 | N½ | 17.3 |
| 7.5 | O½ | 17.7 |
| 8 | P½ | 18.1 |
| 8.5 | Q½ | 18.5 |
| 9 | R½ | 18.9 |
| 9.5 | S½ | 19.4 |
| 10 | T½ | 19.8 |
Quick examples
- US 6 = UK L½ (the most common women's size)
- US 7 = UK N½
- US 9 = UK R½ (a common men's size)
- US 10 = UK T½
Why the two systems differ
Both systems describe the same physical thing — the ring's inside diameter and circumference. The US scale increments numerically (with half sizes), while the UK scale runs alphabetically (A, B, C … with "½" for in‑between sizes). Because the steps don't line up perfectly, most US sizes land on a UK half size.
Need other countries too?
For Europe, Japan and India as well, use the complete international ring size chart, or convert a finger measurement directly with the ring size calculator.
Note: conversions are approximate and rounded; some jewelers vary slightly. Confirm before ordering an expensive ring.