1. First method: measure the circumference (distance around) your finger (with anything flexible, eg: string or a strip of paper. Once you get the circumference, measure it (string or strip of paper) with a ruler. Then you will get the measurement either in mm or cm. Then take a look at the below Ring Size table.
2. Second method: measure the inner diameter (distance across of inner ring) in mm or cm of a ring you currently wear. Then take a look at the below Ring Size table.
* All info can be found here.
Below is the a table for Ring Size:
Ring Size Table
