Eyeglass Frame Sizes Explained and How to Measure Yours

The three numbers on your temple

Turn your glasses over and look at the inside of the temple arm. You will find something like 52 18 140, sometimes with a small square or dash between the first two. Those three numbers are the whole sizing system. All of them are in millimeters.

The first is lens width, the horizontal width of one lens at its widest point. The second is the bridge, the gap between the two lenses where the frame rests on your nose. The third is temple length, the arm from the hinge to the tip behind your ear.

Together they tell you how wide the frame sits on your face, how it perches on your nose, and how it reaches back to your ears. Change one number and the fit changes. That is why two frames that look alike can feel completely different.

How to measure a pair you already own

Often the numbers are printed right there. Check the inner temple first, then the underside of the bridge. If they are worn off, a ruler with millimeters will do the job.

Hold the ruler flat across one lens and measure from the inner edge of the frame on one side to the inner edge on the other. That is your lens width. Next, measure the gap between the lenses at the narrowest point. That is the bridge. Then open the arm and measure from the hinge screw to the tip. That is your temple length.

Do it twice. A millimeter slips easily on a ruler, and the second pass catches it.

Write the three numbers down. If your current pair is comfortable, those figures become your baseline. Our size guide shows how to compare them with the measurements listed for each frame, so you can shop with a number in hand instead of a guess.

Small, medium or large

Labels like small, medium and large are handy, but they are loose. Brands draw the lines in different places, and a medium from one label can sit closer to a large from another. Trust the millimeters over the word.

A better habit is to match your baseline. If your current pair feels right, look for a lens width and bridge close to those numbers. If it feels a little wide, go slightly narrower. If it keeps leaving marks, go slightly roomier. Small shifts matter more than you would expect.

Face shape comes second. Round faces often carry angular frames well, and angular faces often suit softer curves. That is a starting point, not a rule. Fit comes first, and style follows.

How fit affects comfort

A frame that is too narrow squeezes the sides of your head and pinches near the temples. One that is too wide slides around and drifts toward the tip of your nose. A bridge that is too narrow rides high and presses on the sides of the nose. A bridge that is too wide lets the whole frame slip down.

Weight plays a part. A heavy frame rests mostly on the nose, and over a long day that adds up. Lighter materials spread the load. Some frames also have adjustable nose pads, which an optician can tune if you have a low or high nose bridge. Fixed bridges sit on a set shape, so the bridge number deserves a closer look there.

Temple length does quiet work. Too short and the arms push into the sides of your head. Too long and the tips stick out past your ears, so the frame loses its grip.

Fit also matters for the lenses. Your eye should sit near the middle of each lens. If the frame is off, you end up looking through the edge, and that is true for every lens type, especially progressives.

The same numbers appear on sunglasses, so everything above applies there too. Browse our eyeglasses or our sunglasses with your baseline in hand, or start from a specific shelf like men's eyeglasses or women's eyeglasses. Those labels are a convenience, not a fence. Plenty of people wear frames from the other side of the store, and the numbers will tell you whether they work.

A few last tips from the counter. Try to keep your measurements nearby when you shop. Glance at the product page for lens width, bridge and temple length. Compare them with your baseline. And if you plan to wear the frame all day, put comfort ahead of looks. A good frame disappears on your face, and you notice it only when you take it off.

Our FAQ has more on sizing and ordering. If you are stuck between two sizes, email a Gold'Eyes optician or call +33 1 60 02 02 46 with your measurements and the frames you like. We will tell you which one we would pick.