About us
Ring Size Converter is a free, independent tool that translates ring sizes between every major sizing system in the world.
Why we built it
Ring sizing is unnecessarily confusing. A US 7, a UK N½, an EU 54, a French 14, a German 17.3, a Swiss 14.5, a Japanese 14 and a Brazilian 15 all describe exactly the same ring — but almost no shop tells you that. People order the wrong size, pay for resizing, or give up on a purchase entirely.
We built this site to remove that friction. Enter any size in any system, and every other system updates instantly, including inside diameter and inside circumference in both millimetres and inches.
What we offer
- An instant converter covering US, UK, EU, France, Germany, Switzerland, Japan and Brazil.
- A full international ring size chart you can read side by side.
- A step-by-step guide to measuring your ring size accurately at home.
- A growing library of original articles on measuring, fit, metals, resizing and buying rings internationally.
How we source our data
Every conversion in the tool is derived from a single physical value: the inside circumference of the band in millimetres. National size codes are mapped onto that value using the published relationships for each system — the ISO circumference standard, the American arithmetic scale, the British Standards alphabetic scale, and the offsets used in France, Switzerland, Japan and Brazil.
Because different countries round differently, conversions between two coded systems can land on a boundary. Where that happens, we always show the millimetre value so you can make an informed choice rather than trusting a rounded label.
Editorial standards
Every article on this site is written originally for it. We do not republish content from other sites, and we do not use scraped or copied text. Where a topic touches on health — swelling, allergies, stuck rings — we give general information only and recommend professional advice for anything persistent or painful.
How the site is funded
The converter is free and always will be. The site is supported by advertising, which lets us keep every tool and article accessible without a paywall, sign-up or subscription. Ads never influence the content of our guides.
Get in touch
Spotted an error in a conversion, or want a sizing system added? We would genuinely like to hear about it — use our contact form and we will reply.