# Ring size

Ring size is a measurement used to denote the circumference of jewellery and smart rings.

## Measure

An analogic sizing ring stick

Ring sizes can be measured physically by a paper, plastic or metal ring sizer (as a gauge) or by measuring the inner diameter of a ring that already fits.

Ring sticks used to measure the inner size of a ring can be made from a variety of materials including plastic, delrin, wood, aluminium, aluminium with wooden handle and so on. Digital ring sticks also exist.

There are several systems for denoting the sizes of jewellery rings in use around the world:

• In the United States and Canada, ring sizes are specified using a numerical scale, with quarter and half sizes. An increase of a full size is an increase of 0.032 inch (0.8128 mm) in diameter, or roughly 1/10 inch (more precisely, 0.1005 in or 2.55 mm) in inside circumference.
• In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale, with half sizes.
• In India, Japan and China, ring sizes are specified using a numerical scale, that only has whole sizes, and does not have simple linear correlation with diameter or circumference.
• In Italy, Spain, Netherlands, and Switzerland, ring sizes are specified as the circumference minus 40mm. A 50 ISO was a 10 in Switzerland.

For the system prevailing the United States, the Circular of the Bureau of Standards [1] summarizes the situation as: "While there apparently is only one standard in use in the United States, in reality, because of the lack of specific dimensions and because of the errors introduced by the adoption of a common commercial article as a pattern, there are many, although similar, standards." The standards are generally consistent and remain so. There does not appear to have been any improvement in the standard since then.

### Chart

Conversion chart for ring sizes[2]
Inside diameter Inside circumference Sizes
(in) (mm)
ISO
(in) (mm)
ISO
United States,
Mexico
United Kingdom,
Ireland,
Australia,
South Africa and
New Zealand
China,
Japan,
South America
India Italy,
Spain,
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 41.0 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 48.0 I 8 8 8
0.61 15.49 1.92 48.7 J 9 8.75
0.618 15.70 1.94 49.3 5 9 9.25
0.626 15.90 1.97 50.0 K 10 10
0.634 16.10 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 57.0 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 64.0 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 2.70 68.5 12½ Z 26 28.5
0.866 22.00 2.72 69.1 12¾ 29 29
0.874 22.20 2.75 69.7 13 27 30 29.75
0.882 22.40 2.77 70.4 13¼ Z1 30.5
0.89 22.61 2.80 71.0 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 2.90 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 3.00 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

## ISO

The ISO standard for ring sizes is ISO 8653:2016, which defines standard ring sizes in terms of the inner circumference of the ring measured in millimetres.[3]

This international standard specifies a method to measure the ring-size using a ring stick with defined characteristics, which is mainly used during manufacturing steps, and specifies the designation of the ring-size.

For jeweller-consumer relationships, the finger size is measured with a finger gauge set made up of a ring for each size with the same diameter and tolerance as the ring stick ones. The sizes are in millimeters and correspond directly to the outer circumference of the ring stick to the inner circumference of the finger gauge.

In Austria, France, Germany, Belgium and Scandinavia, ring sizes are specified using actual internal circumference in mm (the same as the ISO standard).

### Equations

To convert from US, Canada and Mexico ring sizes (s) to ISO 8653:2016 circumference:

${\displaystyle c=2.55\times s+36.5}$

and for diameter:

${\displaystyle d=0.8128\times s+11.63}$

## References

1. ^ S.W. Stratton, Director (Jan 24, 1921). Circular of the Bureau of Standards, No 43., Jewelers' and Silversmiths' Weights and Measures (Report). United States Department of Commerce. p. 39.
2. ^ "Convert Your Ring Size to MM : Ring Size Guide". Jewelove. Retrieved 2016-11-27.
3. ^