Understanding Frame Measurements
If you look on the inside of your glasses, you'll find a number that looks like: 52 [] 18 135. This information shows you the size of your glasses; the lens diameter, the bridge width and the side length, all measured in millimetres.
Lens diameter
The lens diameter is the width of the lens (in mm), measured from the bridge. It can be a matter of personal choice, but it's also determined by your frame style.
Bridge width
The bridge width is the gap above your nose between the lenses. It's important that this is comfortable - too tight, and the glasses could pinch your nose; too loose and the glasses won't be stable on your face.
Length of side
The length of the side is usually one of three standards – 135, 140 or 145mm. The side should be long enough to sit comfortably over your ears. Glasses with straight sides don't always have this measurement indicated.
There is no hard and fast rules when it comes to selecting glasses as it’s a personal decision, however glasses should frame your face, following the brow line. When it comes to face shapes our rounder frames look better on squarer faces and square frames look more balanced on rounder faces.
If it is your first time buying glasses below is a general size guide to help you. For a better idea of how the glasses will fit, compare the frame measurements to your face using a ruler while facing a mirror.
