International Ring Size Converter
Convert a ring size from one global standard (US, UK, EU, etc.) to all others using the measured diameter or circumference in millimeters.
The Global Standardization of Ring Sizes
Buying rings internationally can be confusing due to the variety of sizing methods. The three main systems are:
- **US/Canada/Mexico:** Uses a numerical scale with half and quarter increments (e.g., Size 7).
- **UK/Australia/Ireland:** Uses an alphabetical scale with half increments (e.g., Size N).
- **European/ISO Standard:** Often uses the inner circumference in millimeters (mm) as the size (e.g., Size 54).
Conversion Accuracy:
All systems ultimately relate back to the **internal circumference or diameter** of the ring in millimeters. This calculator uses a precise master chart based on the inner diameter (mm) to ensure accurate cross-conversion between all systems. Because of manufacturing tolerance, sizes are rounded to the nearest common half/whole size in each respective system.