At many jewelry stores, they have a ring size guide. It is usually a metal tube that has the ring sizes on it. When you slide the ring on the metal guide, it will stop moving up the metal guide when the metal guide gets too big. Then the jeweler can see the ring size on the metal tube. Another way for the average person to measure their ring size is to use a piece of string.
You will need to use the string to measure your ring finger. Instead of wrapping the string around the part of finger where the ring will be placed, you should measure the knuckle of that finger so that the ring will be able to go over the knuckle. Then use a marker to draw a line on the string. Then use a ring size chart.
