Frame width is usually the most important factor in determining a good fit. Frame width is made up of the width of each lens and the bridge, the distance between the lenses.

Frame measurements are made up of three numbers and can be found in the ‘Other Details’ section of the product description of each frame.

Let’s look at a typical frame measurement 51-18-135.

The first number represents the width of one lense in millimeters (mm). This number will give a sense of the frame’s overall width. In general, a larger number means a wider frame.

The second number represents the bridge width and also is a factor in determining fit. This is the distance between the two lenses. If you have a narrow bridge or close set eyes you will want this number to be lower. If you have a wider bridge or wide set eyes, this number can be higher.

The third number is the temple length. This is measurement in millimeters of the ‘arm’ of the frame.

The vertical height or B-Size of the lens is important in determining whether or not multi-focal or progressive lenses can be used in the frame. Any frame with a B dimension of 30mm or more should be fine for a progressive. Some opticians can work with less ie 28mm. Here are quick reference tables for our optical and reading glass frame sizes sorted smallest to largest total width.


C4 Optical Readers
Style Lens Bridge Temple B-size Total Width (Lens x 2 + Bridge)


48 21 140 41.5 117
Lucy 54 18 145 39.4 126
Lily 50 19 135 38.3 119
Rockit 49 23 140 38.4


Bessette 50 19 143 38.6


Bronte 45 25 140 40.7


Sutton 58 15.5 135 48.1


C4 Sunglasses
Style Lens Bridge Temple B-size Total Width (Lens x 2 + Bridge)
Shadow 52 20 135 42.5 124
Grace 49 23.5 140 45.1 121.5
Abigail 53 21 140 43.6 127
Mamie 51 18 145 41.3 120