The frame size is expressed with 3 measurements: lens width, bridge width and temple length
This is the horizontal width of each lens at its widest point. It typically ranges from 40mm to 60mm (1.6 to 2.4 inches approximately).
This is the distance between your two lenses. In short, the bridge width is the space where your frames fit against your nose. The size of this piece ranges from 14mm to 24mm (0.55 to 0.95 inches approximately).
This is the length of the temple from each screw to its temple tip, including the bend that sits on your ear. The temple is typically 120mm to 150mm long (4.7 to 5.9 inches approximately).
To ensure your frames fit perfectly, first determine which size is best for you - we suggest you start by measuring a pair you already own.