Ring Size Converter

They're as close as published international standards allow. US, UK, and EU sizes are all based on the same underlying measurement — inner circumference — so converting between them is precise to within a fraction of a millimeter. The main source of error is your original measurement, not the conversion itself.

The US, Canada, and Mexico use the numeric US scale (typically 3–17). The UK, Ireland, Australia, and South Africa use a letter scale (A–Z, with half sizes and "Z+" sizes beyond Z for larger rings). Most of continental Europe uses the EU scale, which is just the inner circumference in millimeters. Japan, China, and South Korea use their own numeric scale.

Older or vintage rings sometimes use historical sizing systems that don't map cleanly to modern charts, and stamps can also wear down or be inaccurate. The most reliable fix is to measure the ring's inner diameter directly with a ruler and use the Ring Size Calculator instead of relying on the stamp.

Yes for US, EU, diameter, and circumference, which all support half-size (or finer) precision. UK and Japan sizes are discrete steps, so a converted half size is rounded to the nearest available step in that system — which is normal and won't meaningfully affect fit.

No. Ring sizing is based purely on finger circumference and diameter, so the same chart applies regardless of gender. Men's rings simply tend to cluster at the larger end of the scale because, on average, men have larger fingers.