What ring size is 16 mm?
Approximately US size 5.516 mm inside diameter equals 50.3 mm inside circumference.
How this conversion is calculated
The circumference is diameter × π. The US result is rounded to the nearest quarter size because jewellers normally sell discrete sizes rather than an infinitely precise diameter.
Measure only the empty inside of the ring at its widest point. Even a small metal-edge measurement error can change the recommended size.
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