Ring Size Calculator
Ring size from finger circumference or diameter.
Enter your values
Results update instantly as you type — no submit needed.
Results
- US / Canada size
- 6.9
- Inside circumference
- 54 mm
- Inside diameter
- 17.19 mm
- EU / ISO size
- 54
- UK / Australia (approx)
- N
Quick answer
Ring size is set by the inside circumference of the band in millimetres.
US size ≈ (circumference mm − 36.5) ÷ 2.55
How to use the Ring Size Calculator
- 1Wrap a strip of paper around your finger and mark the overlap.
- 2Measure the length in millimetres.
- 3Enter it as the inside circumference.
Frequently asked questions
When should I measure?
Late in the day at normal temperature. Fingers shrink when cold and swell in heat or after salt.
What if I'm between sizes?
Size up, especially for wide bands, which fit more tightly than thin ones at the same nominal size.