How it works
Ring size is based on your finger's circumference in mm. Wrap a string around your finger, mark the overlap, then measure it — or convert an existing ring's inner diameter to circumference. Korea uses a numeric 'ho' size, the US uses its own number scale, the EU uses mm circumference directly, and the UK uses letters.
FAQ
Q. How do I measure a ring's inner diameter?
A. Measure the inner diameter in mm, multiply by π (≈3.14) to get the circumference, then enter that value here.
Q. Does finger size change during the day?
A. Yes — fingers tend to be slightly larger in the evening or warm weather than in the morning or cold. Take a few measurements and average them.