How do I measure my ring size?

Wrap a strip of paper around your finger, mark where it overlaps, and measure the length in mm — that is the inside circumference. Divide by π to get the inside diameter.

Ring Size Converter

Convert ring sizes between US, UK letter, EU number, and inside diameter in mm.

Embed this tool on your site

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How to use this tool

Enter us ring size in the fields above.
Results update instantly as you type — or click Calculate.
Read your uk size and the full breakdown beneath it.

Convert US ring sizes to UK letter codes, EU numbers, and inside diameter in millimetres.

Frequently asked questions

How do I measure my ring size?: Wrap a strip of paper around your finger, mark where it overlaps, and measure the length in mm — that is the inside circumference. Divide by π to get the inside diameter.

References & sources

Wikipedia: Ring size