Ring Size Calculator

Ring sizing is based on finger circumference. US uses a numerical scale; EU sizes equal circumference in mm minus 40; UK uses letters

The calculator uses the standard published formula for ring size. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: EU size = circumference (mm) − 40. Each step in the calculation is shown so you can verify the result manually.