To ensure your frames fit perfectly, you first have to determine which size frames are best for you. The best place to start is with the measurements on a pair you already own. You know those little numbers on the inside of its temple? That's what you're looking for. The frame measurements appear in the following order: lens width, bridge width, and temple length.
To find frame width, measure the front of the frame from screw to screw
Temple length is the measurement in millimeters of the ‘arms' of the frame. This measurement does not vary as much as the others, with 135mm, 140mm, 145mm, and 150mm being the most common options.
Lens Height and Width
Lens height is the distance from the top of a lens to the bottom. Lens Width is the distance from the left side of a lens to the right side.