About Ring Size Finder
Ring Size Finder (ringsizefinderonline.com) is a free online tool that helps you find your ring size accurately at home — no app download, no account, no cost.
Our mission
Buying a ring online should not be a guessing game. Returns for wrong sizes are frustrating and expensive, and sizing confusion between US, UK, EU, Japanese and Indian systems makes it worse. Our mission is simple: give everyone a fast, accurate, standards-based way to check ring size online in under five minutes.
What we offer
On-screen ring sizer
Place an existing ring on your screen and match it to a true-size circle to reveal US, UK, EU and JP sizes.
Finger width calculator
No ring to compare? Measure your finger directly with an adjustable on-screen guide in mm, cm and inches.
International converter & chart
Convert instantly across US, UK, EU (ISO), JP, Indian, Swiss and French systems with a 43-size reference chart.
Printable 1:1 guide
Print a 100%-scale ring mandrel and finger-strip guide for offline measuring, plus brand notes for Oura, Cartier, Tiffany & Co. and Pandora.
How we keep it accurate
- Calculations follow ISO 8653:2016 (Jewellery — Ring size — Definition, measurement and designation), British Standard BS 6882 and US standard sizing.
- All conversions are computed from physical inner diameter and circumference — not rounded lookup tables copied between blogs.
- On-screen tools include a calibration step so circles render at true millimetre size on your display.
- Content is reviewed and updated regularly; this page was last updated in 2026.
Who runs this site?
Ring Size Finder is run by a small independent team passionate about jewellery, e-commerce and practical web tools. We are not a jewellery retailer and we do not sell rings — that independence lets us focus purely on measurement accuracy rather than pushing products. The site is supported by minimal, privacy-friendly operation with no account system and no sale of personal data.