In order to help users in understanding Ring sizes and parameters used in different countries, we have pulled out this chart to assist you in doing so. The chart includes inner diameter as well as circumference of a ring in inches and millimetres.

The Ring sizes are measured using simple tools such as Ring sizer stick (or Ring Mandrel) and Ring finger sizer as shown in the images below.

images   J.K Diamonds (Naman)4174

 

The size parameters differ country wise as shown in the table below.

 

Conversion chart for ring sizes
Inside diameter Inside circumference Sizes
(in) (mm) (in) (mm) US,
Canada and
Mexico
UK,
Ireland,
Australia and
New Zealand
China,
Japan,
South America
India Italy,
Spain,
Netherlands,
Switzerland
0.458 11.63 1.44 36.5 0
0.466 11.84 1.46 37.2 ¼
0.474 12.04 1.49 37.8 ½ A
0.482 12.24 1.51 38.5 ¾
0.49 12.45 1.54 39.1 1 B 1
0.498 12.65 1.56 39.7
0.506 12.85 1.59 40.4 C 0.5
0.514 13.06 1.61 41 1 1
0.522 13.26 1.64 41.7 2 D 2 2 1.75
0.53 13.46 1.67 42.3 2.25
0.538 13.67 1.69 42.9 E 3 3 3
0.546 13.87 1.72 43.6 4 3.5
0.554 14.07 1.74 44.2 3 F 4 4.25
0.562 14.27 1.77 44.8 5 5 4.75
0.57 14.48 1.79 45.5 G 5.5
0.578 14.68 1.82 46.1 6 6 6
0.586 14.88 1.84 46.8 4 H 7 6.75
0.594 15.09 1.87 47.4 7 7.5
0.602 15.29 1.89 48 I 8 8 8
0.61 15.49 1.92 48.7 J 9 8.75
0.618 15.7 1.94 49.3 5 9 9.25
0.626 15.9 1.97 50 K 10 10
0.634 16.1 1.99 50.6 10 10.5
0.642 16.31 2.02 51.2 L 11 11.25
0.65 16.51 2.04 51.9 6 11 12 11.75
0.658 16.71 2.07 52.5 M 12 12.5
0.666 16.92 2.09 53.1 13 13 13.25
0.674 17.12 2.12 53.8 N 13.75
0.682 17.32 2.14 54.4 7 14 14 14.5
0.69 17.53 2.17 55.1 O 15 15
0.698 17.73 2.19 55.7 15 15.75
0.706 17.93 2.22 56.3 P 16 16.25
0.714 18.14 2.24 57 8 16 17 17
0.722 18.34 2.27 57.6 Q 17.5
0.73 18.54 2.29 58.3 17 18 18.25
0.738 18.75 2.32 58.9 R 19 19
0.746 18.95 2.34 59.5 9 18 19.5
0.754 19.15 2.37 60.2 S 20 20.25
0.762 19.35 2.39 60.8 19 21 20.75
0.77 19.56 2.42 61.4 T 21.5
0.778 19.76 2.44 62.1 10 20 22 22
0.786 19.96 2.47 62.7 10¼ U 21 23 22.75
0.794 20.17 2.49 63.4 10½ 22 23.25
0.802 20.37 2.52 64 10¾ V 24 24
0.81 20.57 2.54 64.6 11 23 25 24.75
0.818 20.78 2.57 65.3 11¼ W 25.25
0.826 20.98 2.59 65.9 11½ 24 26 26
0.834 21.18 2.62 66.6 11¾ X 26.5
0.842 21.39 2.65 67.2 12 25 27 27.25
0.85 21.59 2.67 67.8 12¼ Y 28 27.75
0.858 21.79 2.7 68.5 12½ Z 26 28.5
0.866 22 2.72 69.1 12¾ 29 29
0.874 22.2 2.75 69.7 13 27 30 29.75
0.882 22.4 2.77 70.4 13¼ Z1 30.5
0.89 22.61 2.8 71 13½ 31 31
0.898 22.81 2.82 71.7 13¾ Z2 32 31.75
0.906 23.01 2.85 72.3 14 Z3 32.25
0.914 23.22 2.87 72.9 14¼ 33 33
0.922 23.42 2.9 73.6 14½ Z4 33.5
0.93 23.62 2.92 74.2 14¾ 34 34.25
0.938 23.83 2.95 74.8 15 35 34.75
0.946 24.03 2.97 75.5 15¼ 35.5
0.954 24.23 3 76.1 15½ 36 36.25
0.962 24.43 3.02 76.8 15¾ 36.75
0.97 24.64 3.05 77.4 16 37 37.5

 

Ring sizes can be measured physically by a plastic or metal ring sizer, or by measuring the girth of a ring that already fits. There are also online measuring tools available, though they may not be as precise as checking for the size physically.

The circumference of the ring (inner circle) is the distance around it. It is calculated based on the formula, π × diameter (where π=3.14). For example, the Indian size 10 has a diameter 15.9 mm. Hence the circumference would be 3.14 x 15.9 = Approx. 50 mm.

The average ring size for women in India is around Size 13-14 and for men, it is between Size 16-18.

Source