Use a Ring Size Chart
Use a ring that fits you to determine your ring size. Place your ring over the nearest size circle. The inner edge of the ring should align with the outer edge of the circle. If your ring appears to fit between two sizes, buy the larger size.
Use a Finger Size Strip
Print and cut the sizer strip below. Insert the narrow end of the sizer through the "cut here" slot. With numbers on the outside, place the loop around your finger, and pull until the fit is snug but comfortable.
Use a string
1. Wrap a piece of loose string around your finger. Be sure to allow for the size of your knuckle.
2. With a pen, mark the point on the string where the end meets.
3. Using the chart, place the end of the string on the left hand line next to the letter "A" and stretch the string along the sizer toward the numbers.
4. The pen mark on your string should line up with a number to indicate your ring size.