The size of frames are measured per the diagram above and typically in millimeters. The focus is on the length of the temple(or handle as commonly referred to), the width of the bridge and the width of the lens.
The average size of frames is between 64-72mm. For a small face, you may be looking at sizes between 62-64mm, while a wider face may require 72-76mm. The difference in millimeters can make a difference as the fit may be just right or end up being too loose/big or tight. If you have a prescription, it should have a “PD” measurement on it that should assist you in picking the right fit. If you don’t have a prescription, don’t worry, Contact us for assistance.