You’re ahead of the game if you already have a pair of eyeglasses that fits you well. Your glasses may have numbers printed on the inside of the temple arm, which indicate three frame dimensions. The lens size is usually first, then the bridge size, then the temple length. Use the lens size to determine the best frame size. EXAMPLE From left to right, these eyeglass measurements appear in the following order: 1. Lens width - 2. Bridge width - 3. Temple length. If the numbers are 52-20-140, your frame dimensions are: 52 Lens Width 20 Bridge 140 Temple Length Pro Tips: You have a leeway of 2-3 mm on each measurement, except for the bridge. Stick to a leeway of just 2 mm on the bridge.