Frame sizes: The numbers
Eyeglass frame size is indicated by three numbers stamped on the inside of your glasses. These glasses measurements usually appear on the inner surface of one of the frame temples that hold your glasses in place behind your ears.
Specifically, the frame size numbers of glasses are:
The key measurements that describe eyeglass sizes are the eye size, bridge width and temple length.
- The eye size
- The bridge width (bridge size)
- The temple length
All three eyeglass and sunglass frame measurements are specified in millimeters (mm).
For example, let’s say you see these three numbers on the inside of your frames: 54-20-140.
Eye size
The first number — the eye size — is the horizontal width of the lens.
In this case, the openings in the frame for the lenses are 54 mm wide. Generally, the eye size (lens width) of most glasses frames is 40 to 60 mm.
Bridge size
The second number — the bridge size — is the distance between the lenses.
In other words, it’s the size of the “bridge” of the frame that rests on your nose. In this case, the frame bridge is 20 mm wide. The bridge width of most eyeglass frames is 14 to 24 mm.
Temple length
The third number — the temple length — is the length of the “arms” or “stems” of the frame.
Eyeglass temple size is measured from the hinge of the frame to the end tip of the temple. In this case, the temple length is 140 mm. Temple lengths generally range from 120 to 150 mm.
Other considerations
Often, a small square (rather than a dash) will separate the eye size and the bridge size on the frame.
In addition to the eye size, bridge size and temple length, you may see other numbers (or letters and names) stamped on the inside of the frame. These are usually the frame model and/or the color of the frame.
Be aware when ordering prescription glasses that two frames with the same frame measurement may fit differently depending on the style and shape of the eyeglasses.
READ MORE about choosing glasses for your face shape
