Ring Size Conversion Chart

Convert from the ring sizes used in one country or region to the ring sizes used in another country or region. Diameter and circumference measured in millimeters (mm). convert millimeters

Ring sizes by country, measured in millimeters (mm).

US / Canada UK Japan Diameter (mm) Circumference (mm)
4 H 1/2 7 14.8mm 46.5mm
4 1/2 I 1/2 8 15.2mm 48mm
5 J 1/2 9 15.6mm 49mm
5 1/2 L 10 16mm 50.5mm
6 M 12 16.4mm 52mm
6 1/2 N 13 16.8mm 53mm
7 O 14 17.3mm 54.5mm
7 1/2 P 15 17.7mm 55.5mm
8 Q 16 18.1mm 57mm
8 1/2 Q 1/2 17 18.5mm 58mm
9 R 1/2 18 18.9mm 59.5mm
9 1/2 S 1/2 20 19.3mm 61mm
10 T 1/2 21 19.7mm 62mm
10 1/2 U 1/2 22 20.1mm 63.5mm
11 V 1/2 24 20.6mm 64.5mm
11 1/2 W 1/2 25 21mm 66mm
12 Y 26 21.4mm 67.5mm
12 1/2 Z 27 21.8mm 68.5mm
13 Z+1 28 22.2mm 70mm
13 1/2 Z+2 29 22.6mm 71mm
14 Z+3 31 23mm 72.5mm
14 1/2 Z+4 32 23.4mm 74mm
15 Z+5 33 23.9mm 75mm