mm - Diameter In Millimeters. Measurements Converter

Ring sizes in this scale are numerical starting from zero with quarter and half sizes. An increase of a full size adds roughly ⅒ inch in inside circumference of the ring. Sizes smaller than 0 are marked 00, 000, etc.

Please enter partial sizes like this: 5 1/2 or 10 1/4.

Wheat Sheaf is the commonly known gauge for measuring ring sizes in the UK. The official name is British Standard 1283:1945, later in 1987 replaced by British Standard 6820:1987. The wheatsheaf sizes use letters from A to Z, then Z+1, Z+2, etc. with half and quarter-sizes. In the old standard an increase of a full size used to add 1/64th of an inch in ring diameter. The new standard of 1987 redefined the sizes to be based on metric units, now an increase of a full size adds 1.25 mm of an inner circumference. The good news is the old and the new standards are in practice virtually the same.

The smallest possible ring size is A, it corresponds to ring inner circumference of 37.5 mm. For even smaller circumference lengths we still display size A with the percent difference, e.g. A [-10%].

Please enter partial sizes like this: C 1/2 or Z+3 1/4.

This is the official system for measurement of rings that is set as a European standard. It is used in many European countries including France, Germany, Austria, Belgium, Finland, Sweden.

This system defines ring size to be equal to its inner circumference in millimeters.

A few European and South American countries as well as India use another system of sizes. They subtract 40 from the length of the ring circumference in millimeters to get the ring size.

The minimal ring size 0 in this scale corresponds to circumference length of 40 millimeters. For even smaller circumference lengths we still display size 0 with the percent difference, e.g. 0 [-10%].

In addition to European ISO 8653 and alternative European scale, an older system of ring sizes is widely used across the country of Brazil.

The minimal ring size 1 in this scale has inner diameter of 11.8 millimeters. Each size increments the diameter by 0.35 millimeters.

These countries use inner diameter of a ring in millimeters as it's size. In Russia it is officially defined by Russian Standard 117-3-002-95 of 1988.

Some sources say these sizes may also be occasionally used in Germany and Austria.

Many Asian countries use system of sizes that is based on ring diameter starting with size 1 at 13 mm and increasing ⅓ of mm with each size. For rings with smaller diameters we still display ring size 1 with the percent difference, e.g. 1 [-10%].