Ring size
Ring size is a measurement used to denote the circumference of jewellery rings and smart rings.
Measure
Ring sizes can be measured physically by a paper, plastic or metal ring sizer 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.
ISO sizes
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. ISO sizes are used in Austria, France, Germany, Belgium and Scandinavia, as well as some other countries in Continental Europe.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.
Internal ring circumference | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 |
Internal diameter | 15.6 | 15.9 | 16.2 | 16.6 | 16.9 | 17.2 | 17.5 | 17.8 | 18.1 | 18.5 | 18.8 | 19.1 | 19.4 | 19.7 | 20.1 | 20.4 | 20.7 | 21.0 | 21.3 | 21.6 | 22.0 | 22.3 | 22.6 | 22.9 |
Other traditional and regional systems
There are several systems for denoting the sizes of jewellery rings in use around the world:- In the United States, Canada and Mexico 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 in diameter, or roughly 1/10 inch 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 40 mm. A 50 ISO was a 10 in Switzerland.
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 for size conversions
Equations
To convert from US, Canada and Mexico ring sizes to ISO 8653:2016 circumference:and for diameter: