Ring Size Converter

Professional bidirectional ring size conversion for US, EU, UK, CN, JP, and KR standards — plus direct finger circumference input and practical measurement guidance.

Introduction & Usage

Choose a size standard and enter your known ring size, or enter finger circumference in mm.
Results update in real time across all supported standards.
Use Copy or Download to save your conversion report.

Tips: Measure in the afternoon when fingers are slightly larger. If between sizes, choose the larger size or consult a jeweler.

Convert

Unit / Standard

Ring Size

US: 3–13.5 (half sizes OK). Example: 7 or 7.5

Or measure by finger circumference

Finger Circumference (mm)

Enter mm directly to convert all standards (overrides ring size when filled).

Output

Measurement Tutorial

Cut a thin strip of paper or use non-stretch string.
Wrap it snugly around the finger base where the ring will sit.
Mark the overlap, lay flat, and measure length in millimeters.
Enter that value in Finger Circumference (mm) for the most accurate conversion.
Alternatively, measure an existing ring’s inner diameter (mm) and multiply by π (3.1416) for circumference.