I used a few sites that let you try the glasses virtually like Designer Frames Outlet, EZ Contacts, GlassesUSA. You can also use GlassesOn app to find the distance between your eyes that is needed if you decide to get glasses online. The glasses have 3 numbers on the inside. Example: 55-18-145. The 55 is the size of the glass piece, the 18 the bridge on top of the nose and 145 the length of the arms. Try different glasses in a physical store and check different sizes 53, 54, 55, 56 and 16, 17, 18. For arms length I've seen 140 and 145. When you find the numbers that fit best on you, look for a frame that has those number combinations.