Aside from glancing in a mirror to decide whether a pair of frames suits your style and fits your face, there are a few objective facts that should feature in your assessment. Let’s start with frame shape.
You’ll hear lots of expert opinions on which frame shape — for instance, round, rectangular, cat eye, etc. — is best suited to which face shape — oval, square, triangular, heart, and round. While these recommendations might work in general, they leave out one crucial factor: personality. Big personalities can pull off bright colours and offbeat styles, large or small, in a way that quieter types of men and women can’t. But let’s start with the basics.
As a rule of thumb (and this changes with fashion) the width of the frame should not extend beyond the width of your head. There is a trend now for 'bold' frame, glasses that pay no attention to the width of anyone's head to become the main focus of attention, or to put it glibly: you don't wear them, they wear you. These frame (by Dita, Akoni, Jacques Marie Mage, Robert La Roche, and their imitators) can certainly work for a person wuth a bold personla style. Thing is, however stylish and attractive these big acetate frames might liik in the shop, they don't work for everyday. So, try them on, take a breath and be honest with yourself. Oh, and, take a trusted fiend along for second opinion.
Now, the measurement. On account of my narrow head and small face I limit my choices to frames with a width — that’s the distance between the upper corners of the frame — to around 135 millimetres. With certain frames (I wear a Jacques Marie Mage Zephirin frame) I can push it closer to 140 mm, but that’s a rare event. The best thing you can do before you order your frame is to take a measurement of the frames you feel most comfortable in, use that as a baseline, and give yourself some wiggle room to account for the model of a particular frame you fancy.
Remember that in assessing the size of a frame and its effect on your personal style, you should be aware of a few variables. After te overall width of the frame (which is different form the combined width of the lenses, a question I'll get to later), you'll find engraved on the inner side of one of the temple arms the width of the bridge. That's the bit in the middle that sits on the bridge of your nose. In my case, with a few exceptions, I look for a width of between 14 and 18 millimeters. This measurment is factor in determining how far apart your lenses lie, which is turn determines where your eyes fit inside the lenses, high or low, wider apart or closer together. For the sake of clear vision, distances can be compensated for by your optician when measure your Pupillary Distance (PD), but it is another variable to note when choosing your frame.
Another variable: lens size. You’ll find this measurement, too, on the inside of the temple arm. My upper limit, again, depending on the style, is anything under 45 millimetres, but I aim to keep the lens width — measured across the widest part of the lens — under 40 mm. I own pairs of frames with wider lens widths, but with thinner frames. For instance with my Reykjavik Eyes Alvar with its 47 mm lens, keeps the overall frame width under 130 mm.
You should also consider the height of the lens, their vertical measurement. With a smaller face like mine, too deep a frame takes up too much face real estate, so my ideal measurement for everyday glasses is around 38 mm. With sunglasses both measurements increase for the greater coverage I need to protect my eyes and skin from UV rays.
Here’s a fast and loose rundown of face shapes and the sorts of frames best suited:
If you've got an oval face, one whose proportions are evenly distributed, you’ve hit the genetic jackpot: you will look good in any frame — round, cat eye, rectangle, Wayfarer, geometric, shield shape, browline, square, oval, aviator.
A round face won't easily accommodate round frames, cat eye, Wayfarer, browline or oval, so stick to frames that offer a contrast, that is, angles that cut across the soft contours of your cheeks and forehead.
A square face, one longest around the jawline and forehead, should avoid rectangular frames, square frames and geometric frames that only amplify the hard angles of your bone structure.
You see a theme emerging here? Contrast is what you’re after.
You have a triangular face if your forehead is wide above high cheekbones and your chin is narrow, in general, you’ll struggle to suit rectangular frames, browline frames or oval frames. Unless you’ve got the fizzy personality to pull them off.
A heart shaped face is one with a wider forehead, narrow chin and rounder cheeks. You’ll probably be happiest avoiding round frames, square frames, aviators and anything geometric (though not including shield frames — straight edge on onto of a rounded bottom half — which suit everybody).
Now, these are just guidelines, not hard and fast rules, so let your spirit roam free.