A Guide to Frame Sizes
Most frames have the size written on them.
If you have a pair of existing glasses and you want to know the size, look on the inside of the side arm or on the inside of the nose bridge of the glasses.
The image below shows how the numbers are commonly displayed
The 55 refer to the width of a single lens in mm.
The 55 refer to the width of a single lens in mm.
The 18 refers to the bridge of the frames in mm.
In this website, when you see size, it refers to the width of a single lens. This is usually a value between 40 and 60mm.