Ring Sizer is an independently maintained browser tool for exploring ring-size measurements and approximate international conversions. It is maintained under the name Ring Sizer. This website does not present itself as a jeweler, a certification body or a physically validated measuring instrument.
What the site helps you do
You can match an existing ring’s inner opening, try a visible finger-width estimate on a supported screen, convert a diameter or circumference you already measured, compare reference sizes, or download a printable circle guide. The measurement guide explains when each method is useful.
The finger tool treats visible width as an equivalent circular diameter. It does not measure around the finger. Screen scale, finger shape, pressure and alignment can affect the result; a size number from the page does not establish comfortable fit.
Reference data and maintenance
The current table uses GIA’s US 3–13.5 half-size diameters and its UK and Japanese mappings, plus Peter Stone diameters for US 14–15. EU entries are calculated, rounded inner circumferences. Missing equivalents remain missing. Phone profiles use published Apple, Google and Samsung specifications.
The method and sources page links to those references and documents the screen calculations, supported models and unvalidated assumptions. Automated tests check data consistency, calculations and browser behaviour. They do not substitute for ruler-to-screen, physical printer or finger-gauge validation.
Maintenance follows reported issues and implementation changes rather than a promised fixed update schedule. A report about an incorrect model match, unclear instruction or conflicting size reference can be sent through the contact page. We do not publish invented reviewer qualifications or claim physical tests we have not performed.
Update record
- October 29, 2026: published the six-page tool, converter, guide, printable circle PDFs and methodology. Device and printable geometry checks were digital; physical accuracy remained unvalidated.
- November 1, 2026: added dedicated About, Contact and Privacy pages and linked them from the footer. The privacy notice describes the actual camera-free implementation.
Your measurements and questions
Measurement calculations run locally, with limited screen settings stored in the browser. The privacy policy explains storage, hosting requests, shared links and email enquiries. For a purchase, compare your original reading with the seller’s own chart and obtain a physical fitting when needed.