Ring sizing standards differ between countries and jewellers, so check the shop’s chart. This tool gives the US size only.
Frequently asked questions
How do I measure my ring size?
Wrap a thin strip of paper or string around the base of the finger, mark where it overlaps and measure the length in millimetres. That is the circumference.
What is the formula?
US size ≈ (inside diameter in mm − 11.63) ÷ 0.8128. Diameter is circumference ÷ π.
Why might the ring still not fit?
Fingers swell with heat and in the afternoon, and a wide band feels tighter. Many jewellers advise sizing up a quarter to half size for wide bands.