Measure an existing ring’s inner diameter with a ruler or caliper (mm) and match to a size chart
Measure an existing ring’s inner circumference with a flexible measuring tape or string (mm) and match to a size chart
Use a ring sizer tool or printable ring sizer (print at 100%, cut out, and try sizes)
Wrap a strip of paper or string around the finger, mark where it overlaps, then measure the length (mm) and match to a size chart
Measure the finger circumference at the time you plan to wear the ring (preferably when hands are warm) and match to a size chart
If between sizes, choose the larger size for comfort or the smaller size for a snug fit
For non-round shapes (comfort fit bands), consider sizing slightly for comfort
Confirm by trying the matched size on the same finger and checking for easy sliding and minimal gaps at the knuckle