Cut a strip of paper or a piece of
non-stretchy string.

Wrap it snugly around the base of your finger.

Please remember not to wrap the string or paper too tightly around your finger, or you will have problems with getting the ring over your knuckle. Keep in mind that your fingers will swell, and you should leave a little room for the ring.

Mark the point on it where it completes the circle.

It shouldn't be too tight, nor too loose.

Measure the length of the string or paper

Measure it from the beginning to the mark with a ruler or tape measure. This is the circumference of your finger.

Find out your ring size on the conversion chart HERE

Find "Inside circumference" measurement on the conversion chart to find the corresponding ring size.