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


  • The ISO standard for ring sizes is ISO 8653:1986, which defines standard ring sizes in terms of the inner circumference of the ring measured in millimeters.

  • 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,[2] 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 Austria, France, Germany, Belgium and Scandinavia, ring sizes are specified using actual internal circumference in mm (the same as the ISO standard). In some countries, half sizes may be used.

  • In Italy, Spain, Netherlands, and Switzerland, ring sizes are specified as the circumference minus 40mm. A 50 in Germany will be a 10 in Switzerland.

    While I always recommend that you get properly sized at a local jewelry store however, there is a simple process that you can use at home.


  • Finding your ring is a very simple process that can be done with minimal resources. All you need is a ruler and a piece of string.

  • 1. Wrap the string around your finger and mark where it begins to overlap. 

  • 2. Straighten the string out and measure it with a ruler. This is the circumference measurement of your finger. 

  • 3. Compare this with the size chart below.

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