International Ring Size Chart: US, UK, Europe, and Asia Sizing Explained

If you are purchasing jewelry from an international retailer, you will need to navigate different sizing standards. Ring sizes are not standardized globally; different countries use different scales to represent the same interior dimensions.

Regional Sizing Frameworks

The United States and Canada use a numerical scale based on diameter inches. The UK, Ireland, and Australia use an alphabetical scale, where each letter corresponds to a specific millimeter circumference. European countries like France use the exact inside circumference in millimeters as their size designation.

Germany uses the inside diameter in millimeters as their sizing standard. Japan uses a unique numerical scale that increases in diameter steps. Understanding these systems is essential when ordering fine jewelry online.

"A US size 7 is equivalent to a UK size O, a French size 54.4, and a Japanese size 14, all representing an inside diameter of 17.3 mm."

Our online cm to mm ring size converter maps these regional differences automatically. You can also explore how diameter relates to circumference in our guide on ring size diameter vs circumference.