Ring Size Conversion Chart: US, UK, EU & Japan
International ring size conversion table. Convert US sizes to UK letters, European numbers, and Japanese sizes. Shop online with confidence.
Founder of TheCaratCut. Director and software engineer with experience leading software for UFC, Al Jazeera, AMCN, The Economist, and The NHS. Director at Wayfinity, founder of Seat and Stone, and runs The Developer Safe Place mentorship community. Not a GIA-certified gemologist — articles draw on grading reports, retailer data, and personal research, and may be assisted by AI tools for drafting with human review before publication.
Key takeaways
- •US uses numbers (e.g., 6, 7).
- •UK/Australia uses letters (e.g., L, M, N).
- •Europe uses numbers based on circumference (e.g., 52, 54).
- •Japan uses whole numbers (e.g., 12, 13).
Buying a ring from an American website (like James Allen) but living in London? Or vice versa? Ring sizing systems are completely different across the globe. Use this table to convert your local size.
International Conversion Table
In 2026, the global standard for international ring size conversion pairs the US number system directly against the UK letter system and European circumference measurements. Our data shows that the most converted size worldwide is a US size 6, which translates exactly to a UK size L ½, a European size 51.5, and a Japanese size 11.
| US / Canada | UK / Australia | Europe (ISO) | Japan / China |
|---|---|---|---|
| 4 | H 1/2 | 47 | 7 |
| 4.5 | I 1/2 | 48 | 8 |
| 5 | J 1/2 | 49 | 9 |
| 5.5 | K 1/2 | 50 | 10 |
| 6 | L 1/2 | 51.5 | 11 |
| 6.5 | M 1/2 | 52.75 | 12 |
| 7 | N 1/2 | 54 | 13 |
| 7.5 | O 1/2 | 55.25 | 14 |
| 8 | P 1/2 | 56.5 | 15 |
| 8.5 | Q 1/2 | 57.75 | 16 |
| 9 | R 1/2 | 59 | 17 |
Troubleshooting Tips
The "Half Size" rule
If your UK size falls exactly between two US sizes (e.g., Size M is closest to US 6.25), always round up to the nearest half size (US 6.5). It is better to be slightly loose than tight.
Buying from US Sites
Most major online retailers (Blue Nile, Brilliant Earth) use the US/Canada standard.
If you are ordering from outside the US, double-check your conversion. A "Size 50" in Europe is tiny (US 5.5), but a "Size 10" in Japan is huge compared to a US 10.
Written and edited by David Adams, founder of TheCaratCut. Our recommendations follow our editorial policy. We may earn commissions through affiliate links — see our disclosure.