Ring size -Italian size-

Measure the inside diameter of a ring you already have.
It is important that the measurement is accurate to the millimeter. You can compare the table below to verify that some measurement corresponds to the diameter.
 

Measure the inner diameter of a ring you already own.
It’s important that the measurement is accurate to the millimeter. You can use the table below to check which size corresponds to the diameter.

If you don’t have a ring that fits well, you can try wrapping a soft measuring tape or a plastic one as close to the knuckle as possible, since it’s the widest part of the finger. This way, you shouldn’t have trouble slipping on the ring.