💍 Ring Size Converter

Ring size notation differs by country. The US uses numbers with half steps (3, 3.5, …), the UK uses letters (F, G, …), the EU uses numbers close to the inner circumference in mm (e.g. 52, 54), and Japan and Korea use integer "go/ho" sizes. Japanese and Korean sizes effectively share the same system, so this converter shows them identically. All systems ultimately describe the ring's inner diameter or inner circumference, so knowing a mm measurement lets you convert to any notation.

The most accurate method is measuring the inner diameter of a ring that already fits well (in mm, inside edge to inside edge). Without a ring, wrap a paper strip or string around the finger, mark where it overlaps, and measure the length — that gives the circumference. Finger size changes between morning and evening and across seasons, so measure several times, and if your knuckle is large, size for the knuckle.