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Frame Size Guide

Frame Size Guide Frame Measurements Explained

  1. The first number is the lens diameter – this is the width of the lens measured in mm. The lens diameter is very much a matter of personal choice but may also be determined by your chosen frame style which should suit your face shape and size.
  2. The second is the bridge width – this is the gap above your nose between the lenses. This measurement is crucial for making sure your new glasses fit comfortably. If the bridge size is too small the glasses could pinch your nose. Conversely if it is too wide your new glasses may not be stable on your face.
  3. The third number is the side length – this is the overall length of the side as measured from the dowel point (hinge) to the end of the side. Typically side lengths come in one of three standards – 135mm 140mm or 145mm. When choosing an side length remember that the side should be long enough to sit comfortably over and behind your ears. Please remember that glasses with straight sides may not always have this measurement indicated.


The lens diameter and bridge width are always together either on the bridge or side of the frame. The side length can appear with the other two measurements or on its own elsewhere on the side.

(Note: You may only see one number displayed on sunglasses this would be the width of the visor lens)

Choosing the right frame size and shape is an important part of ordering your new glasses. Not only will it affect the look of the glasses on your face it will also affect how comfortable they are to wear.

The Optic Shop has a quick and easy way to search for frames by frame measurement.