Having your finger sized by a professional jeweller is the most accurate way of finding your ring size. However if you do need to do this at home, this ring sizing chart might come in handy.
Find a ring that fits on the finger you are buying for and measure its inner diameter. The inner diameter is the measurement of the widest point on the inside of a ring. Use the chart below to convert the inner diameter to a ring size.
If you’re looking to find someone’s ring size in secret, check out this guide to finding a ring size (without spoiling the big surprise).

Find your ring size
INNER DIAMETER (MM) | US SIZE | JAPANESE SIZE | AUSTRALIAN/BRITISH SIZE | GERMAN SIZE | SWISS SIZE |
---|---|---|---|---|---|
15.27 | 4 1/2 | 8 | I 1/2 | 15 1/4 | — |
15.70 | 5 | 9 | J 1/2 | 15 3/4 | — |
16.10 | 5 1/2 | 11 | L | 16 | 11 3/4 |
16.51 | 6 | 12 | M | 16 1/7 | |
16.92 | 6 1/2 | 13 | N | 17 | 14 |
17.35 | 7 | 14 | O | 17 1/4 | 15 1/4 |
17.75 | 7 1/2 | 15 | P | 17 3/4 | 17 3/4 |
18.19 | 8 | 16 | Q | 18 | — |
18.53 | 8 1/2 | 17 | Q 1/2 | 18 1/2 | — |
18.89 | 9 | 18 | R 1/2 | 19 | — |
19.41 | 9 1/2 | 19 | S 1/2 | 19 1/2 | — |
19.84 | 10 | 20 | T 1/2 | 20 | — |
20.20 | 10 1/2 | 22 | U 1/2 | 20 1/4 | — |
20.68 | 11 | 23 | V 1/2 | 20 3/4 | — |
21.08 | 11 1/2 | 24 | W 1/2 | 21 | — |
21.49 | 12 | 25 | Y | 21 1/4 | 27 1/2 |
21.89 | 12 1/2 | 26 | Z | 21 3/4 | 28 3/4 |
22.33 | 13 | 27 | — | 22 | — |