<Ul> <Li> 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 . </Li> <Li> 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 . </Li> <Li> In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale, with half sizes . </Li> <Li> 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 . </Li> <Li> 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 . </Li> <Li> 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 . </Li> </Ul> <Li> 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 . </Li> <Li> 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 . </Li> <Li> In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale, with half sizes . </Li>

Are canadian and american ring sizes the same