To choose a frame that fits your size, you must first determine the frame's dimensions. To do so, please refer to the diagram below and measure it as follows: If you wear spectacles and already have a pair on hand, examine the inside side of the temples (arms) of those glasses. You will usually find there a number of measurements listed in millimeters. These are the dimensions you need to know. Now that you know the length and width of your frame, you can choose a size based on these measurements. The most common sizes are listed below. However, since each person's face is different, it's best to try on several frames until you find one that fits comfortably. Frame Size Medium = 22-25 mm long x 9-10 mm wide Large = 27-30 mm long x 11-12 mm wide X-Large = 33-35 mm long x 13-15 mm wide Choose a size larger than your normal size for a looser fit. A loose fit allows for greater comfort while wearing glasses. If you have an eye exam with our optometrists, they will be able to tell you your correct frame size. They may also be able to suggest some brands and styles that match your face shape.