1) Measure your finger using a piece of string.
Simply wrap a piece of string around your finger (be careful that it is not too tight or loose - the ring has to go around your knuckle as well) and then measure the length of the string in millimeters. The length in milimiters corresponds to the following ring sizes
2) Have your finger measured.
Go to the closest “brick and mortar” jewellery store and have your finger measured using a ring sizer.