Tool Introduction
The Ring Size Converter matches a ring measurement - inside circumference or diameter in millimetres - to the most common sizing systems: US numeric sizes (including half sizes), UK letter sizes, and EU sizes. The recommended row is highlighted on the chart so you can see how the systems line up.
Ring sizing varies slightly between jewellers and countries, so treat the result as a guide. Between two sizes? Pick the larger one, especially for wide bands or warmer days when fingers swell slightly. When in doubt, a jeweller can size your finger precisely in a minute.