Measure an existing ring's internal diameter.

How to do it?

14.9 mm Size 4 17.3 mm Size 7
15.7 mm Size 5 18.1 mm Size 8
16.5 mm Size 6 19.0 mm Size 9

 

Measure your finger's circumference.

46.8 mm Size 4 54.4 mm Size 7
49.3 mm Size 5 57.0 mm Size 8
51.9 mm Size 6 59.5 mm Size 9