Heads and faces come in different shapes and sizes; therefore eyeglass frames must be made to fit a range of head and face sizes. The glasses industry uses standardized measurements to help manufacturers and optics workers dispense frames that properly fit their customers. By learning a few key facts, you can decipher the numbers on your glasses frame.
Pick up the glasses frame and look for a series of three numbers, separated by dashes or other symbols, printed on the inside temple area. The type may be so small, you will need to wear another pair of glasses to read them.
Look at the first number in the series. It indicates the lens size.
Look at the second number. It refers to the bridge size, which indicates the fit on your nose.
Look at the third number. It indicates the temple length--the parts that fit over your ears.