Official international ring size conversion

by | Jul 13, 2020


It is important to establish your correct ring size, and this varies from one finger to the next, and between hands. Usually, the hand you write with will have larger ring sizes. What is considered comfortable is very personal- some people prefer a snug fit, others quite loose. There is no right answer provided that the ring is secure.

Ring sizes are expressed differently by region, which can create uncertainty when travelling or purchasing jewellery abroad.

The US and the UK have adopted alpha numeric sizing systems, which are susceptible to minor variations as there are often slight differences from one ring gauge/stick to the next.

The internal circumference measurement is absolute and unambiguous. For example, a size 52 indicates that the inside circumference of the ring is 52mm.

There are two ways to measure ring size: leading edge and middle size. This needs to be specified when quoting your ring size.

Try to avoid measuring your ring size if you are hot (your fingers will be swollen and the measurement will be too big) or too cold (they will measure up too small).

Be aware that if the ring has a wider band width, it will require a larger ring size than usual to comfortably slide over the knuckle of the finger.

Ideally, visit your jeweller for an accurate size fitting. The table below provides a helpful conversion between countries and regions.

Inside Diameter  Inside Circumference Sizes
MM Inches MM Inches British & Australian  US & Canada French & Russian German Japanese Swiss
9.91 0.390 31.13 1.22 – 0000 – – – –
10.72 0.442 33.68 1.39 – 00 – – – –
11.53 0.454 36.22 1.43 – 0 – – – –
11.95 0.474 37.54 1.49 A 1/2 – – – –
12.18 0.482 38.26 1.51 A 1/2 3/4 – – – –
12.37 0.487 38.86 1.53 B 1 – – 1 –
12.60 0.496 39.58 1.56 B 1/2 1 1/4 – – – –
12.78 0.503 40.15 1.58 C 1 1/2 – – – –
13.00 0.512 40.84 1.61 C 1/2 1 3/4 – – – –
13.21 0.520 41.50 1.63 D 2 41 1/2 13 1/2 2 1 1/2
13.41 0.528 42.13 1.66 D 1/2 2 1/4 – – – –
13.61 0.536 42.76 1.68 E 2 1/2 42 3/4 13 3/4 3 2 3/4
13.83 0.544 43.45 1.71 E 1/2 2 3/4 – – – –
14.05 0.553 44.14 1.74 F 3 44 14 4 4
14.15 0.557 44.45 1.75 F 1/2 3 1/8 – – – –
14.25 0.561 44.77 1.76 F 3/4 3 1/4 – – – –
14.36 0.565 45.11 1.77 G 3 3/8 45 1/4 – 5 5 1/4
14.45 0.569 45.40 1.79 G 1/4 3 1/2 – 14 1/2 – –
14.56 0.573 45.74 1.80 G 1/2 3 5/8 – – 6 –
14.65 0.577 46.02 1.81 H 3 3/4 46 1/2 – – 6 1/2
14.86 0.585 46.68 1.84 H 1/2 4 – 15 7 –
15.04 0.592 47.25 1.86 I 4 1/4 47 3/4 – – 7 3/4
15.27 0.601 47.97 1.89 I 1/2 4 1/2 – 15 1/4 8 –
15.40 0.606 48.38 1.90 J 4 5/8 49 15 1/2 – 9
15.53 0.611 48.79 1.92 J 1/4 4 3/4 – – – –
15.70 0.618 49.32 1.94 J 1/2 5 – 15 3/4 9 –
15.80 0.622 49.64 1.95 K 5 1/8 50 – – 10
15.90 0.626 49.95 1.97 K 1/4 5 1/4 – – – –
16.00 0.630 50.27 1.98 K 1/2 5 3/8 – – 10 –
16.10 0.634 50.58 1.99 L 5 1/2 51 3/4 16 – 11 3/4
16.30 0.642 51.21 2.02 L 1/4 5 3/4 – – – –
16.41 0.646 51.55 2.03 L 1/2 5 7/8 – – – –
16.51 0.650 51.87 2.04 M 6 52 3/4 16 1/2 12 12 3/4
16.71 0.658 52.50 2.07 M 1/2 6 1/4 – – – –
16.92 0.666 53.16 2.09 N 6 1/2 54 17 13 14
17.13 0.674 53.82 2.12 N 1/2 6 3/4 – – – –
17.35 0.683 54.51 2.15 O 7 55 1/4 17 1/4 14 15 1/4
17.45 0.687 54.82 2.16 O 1/2 7 1/4 – – – –
17.75 0.699 55.76 2.20 P 7 1/2 56 1/2 17 3/4 15 16 1/2
17.97 0.707 56.45 2.22 P 1/2 7 3/4 – – – –
18.19 0.716 57.15 2.25 Q 8 57 3/4 18 16 17 3/4
18.35 0.722 57.65 2.27 Q 1/2 8 1/4 – – – –
18.53 0.729 58.21 2.29 Q 3/4 8 1/2 – 18 1/2 17 –
18.61 0.733 58.47 2.30 R 8 5/8 59 – – 19
18.69 0.736 58.72 2.31 R 1/4 8 3/4 – – – –
18.80 0.740 59.06 2.32 R 1/2 8 7/8 – – – –
18.89 0.748 59.34 2.35 R 3/4 9 – 19 18 –
19.10 0.752 60.00 2.36 S 9 1/8 60 1/4 – – 20 1/4
19.22 0.757 60.38 2.38 S 1/4 9 1/4 – – – –
19.31 0.760 60.66 2.39 S 1/2 9 3/8 – – – –
19.41 0.764 60.98 2.40 S 3/4 9 1/2 – 19 1/2 19 –
19.51 0.768 61.29 2.41 T 9 5/8 61 1/2 – – 21 1/2
19.62 0.772 61.64 2.43 T 1/4 9 3/4 – – – –
19.84 0.781 62.33 2.45 T 1/2 10 – 20 20 –
20.02 0.788 62.89 2.48 U 10 1/4 62 3/4 – 21 22 3/4
20.20 0.797 63.46 2.50 U 1/2 10 1/2 – 20 1/4 22 –
20.32 0.800 63.84 2.51 V 10 5/8 63 – – 23 3/4
20.44 0.805 64.21 2.53 V 1/4 10 3/4 – – – –
20.68 0.814 64.97 2.56 V 1/2 11 – 20 3/4 23 –
20.76 0.817 65.22 2.57 W 11 1/8 65 – – 25
20.85 0.821 65.50 2.58 W 1/4 11 1/4 – – – –
20.94 0.824 65.78 2.59 W 1/2 11 3/8 – – – –
21.08 0.830 66.22 2.61 W 3/4 11 1/2 – 21 24 –
21.18 0.834 66.54 2.62 X 11 5/8 66 1/4 – – 26 1/4
21.24 0.836 66.73 2.63 X 1/4 11 3/4 – – – –
21.30 0.839 66.92 2.64 X 1/2 11 7/8 – – – –
21.49 0.846 67.51 2.66 Y 12 67 1/2 21 1/4 25 27 1/2
21.69 0.854 68.14 2.68 Y 1/2 12 1/4 – – – –
21.89 0.862 68.77 2.71 Z 12 1/2 68 3/4 21 3/4 26 28 3/4
22.10 0.870 69.43 2.73 Z +1/2 12 3/4 – – – –
22.33 0.879 70.15 2.76 Z+1 13 – 22 27 –
22.60 0.890 71.00 2.80 Z+1.5 13.5 – – – –
22.69 0.893 71.28 2.81 Z+2 – – – – –
22.92 0.902 72.00 2.83 Z+2.5 – – – – –
23.06 0.908 72.45 2.85 Z+3 – – – – –
23.24 0.915 73.01 2.87 Z+3.5 – – – – –
23.47 0.924 73.73 2.90 Z+4 – – – – –
23.55 0.927 73.98 2.91 Z+4.5 – – – – –
23.87 0.940 74.99 2.95 Z+5 – – – – –
24.27 0.956 76.25 3.00 Z+6 – – – – –