Is the ring size converter free?

Yes, completely free with no signup and no usage limits.

Does my data leave my device?

No. All conversions run in JavaScript inside your browser. Nothing is sent to any server.

Yes. The tool is mobile-first and works on iPhone Safari and Android Chrome.

Select a ring size in any standard to see equivalents, or enter a finger diameter or circumference to find your size.

100% client-side · no upload

System Size

Or measure from diameter / circumference

Diameter (mm) Circumference (mm)

Select a sizing system and choose your ring size to see all equivalents.
Or measure the inside diameter or circumference of an existing ring in millimetres and enter it below.
The closest standard size in all systems is shown instantly.

Is the ring size converter free?: Yes, completely free with no signup and no usage limits.
Does my data leave my device?: No. All conversions run in JavaScript inside your browser. Nothing is sent to any server.
Does it work on mobile?: Yes. The tool is mobile-first and works on iPhone Safari and Android Chrome.