Always choose the ring size of the largest finger you’ll be wearing the ring on. Wrap a piece of string around your finger. Measure the length with a ruler then match to the circumference below.

Ring Diameter Circumference  UK US EU
15.7mm 49.3mm J 5 48.5
16.51mm 51.9mm L 6 51
17.34mm 54.4mm N 7 54
18.14mm 57mm Q 8 57
18.95mm 59.5mm R 9 59