How to measure your face for sunglasses, and which number actually decides the fit

You need three numbers: how wide your face is across the cheekbones, how wide the gap between your eyes is at the bridge, and how far it is from temple to temple. With those, you can tell whether a frame will fit before you order it, which is the entire point when you are buying online.

There is also a shortcut that is more accurate than any of this, and I will give it to you first, because most people should use it instead.

The shortcut: measure a pair that already fits

If you own sunglasses or glasses that fit well, the numbers are printed on the inside of the left arm. Something like:

`` 60 □ 15 145 ``

That is lens width, bridge width, and temple length, all in millimetres. Write them down, and shop for frames within a few millimetres of each.

This beats measuring your face because it skips a translation step. Your face measurements have to be converted into frame measurements by rules of thumb that are approximate at best. A frame that already fits has done that conversion for you, correctly, in the real world.

If you have a pair that fits, stop here. Use those numbers.

If you do not have a reference pair

You need a soft tape measure — the fabric kind used for sewing — and a mirror. A rigid ruler works for two of the three but is awkward for the first.

Take each measurement twice, on different occasions if you can be bothered. Faces are not symmetrical and hands are not steady; two readings catch the obvious errors.

1. Face width, across the cheekbones

The most important of the three.

Find the widest point of your cheekbones — usually just below and slightly outside the outer corner of each eye. Measure straight across from the outer edge of one to the outer edge of the other.

Most adult faces land between 125mm and 150mm. Under 125mm is a narrow face; over 150mm is a wide one.

This number sets the frame width you need. The rule: the total width of the frame front should equal your face width, or exceed it by up to about 5mm. Never less. A frame narrower than your cheekbones will splay its arms to reach your ears, grip your temples, and slide down your nose all day — which is the mechanism behind almost every complaint in our slipping sunglasses piece.

2. Bridge width

Measure the gap between your eyes at the narrowest point of your nose bridge — roughly level with the inner corners of your eyes.

Typical range is 14mm to 24mm. This number maps fairly directly onto the bridge measurement printed on a frame.

Too narrow a bridge and the frame perches high and pinches. Too wide and it slides straight down. If your bridge is low or shallow rather than narrow — a different problem — our piece on low nose bridge fit covers why standard frames slide on some faces regardless of the number.

3. Temple to temple

From the flat area at one temple, straight across the front of your face, to the same point on the other side.

This is close to face width on most people but not identical, and it is the better predictor of whether the arms will sit comfortably. Typical range is 120mm to 150mm.

Translating face width into frame width

Here is the part that trips people up: the lens width printed on a frame is not the frame's width.

A frame marked 60-15-145 has two 60mm lenses and a 15mm bridge. That is 135mm of lens and bridge. But the rims around the lenses and the hinge housings add width — typically 5 to 12mm total depending on the frame's construction.

So that 60-15 frame is likely to measure somewhere around 140 to 147mm across the front.

Most retailers do not print total front width. If it is given, use it. If not, lens width plus bridge width plus about 8mm is a reasonable estimate for a plastic frame, and a little less for a thin metal one.

Our own T01 is 60-15-145 with a measured front width of 140mm, and the fit guide states that figure explicitly rather than making you derive it.

The quick sanity checks that need no tape

Three things you can judge in a mirror, which between them catch most bad fits.

Can you see your cheeks past the outer edge of the lenses? If yes, the frame is too narrow.

Does the top rim touch your eyebrows? If yes, the lens is too deep for your face.

Do the arms touch the sides of your head before they reach your ears? If yes, too narrow again — this is the same fault as the first check, felt rather than seen.

Our six-point fit check runs through the full version of this, including the look-down test that catches what a mirror cannot.

What the numbers do not tell you

Measurements narrow the field. They do not finish the job, and it is worth being honest about the limits.

Face shape is not captured by width. Two faces with identical cheekbone measurements can suit very different frame shapes depending on whether the jaw is square or soft, the forehead broad or narrow. Our face shape guide covers the one rule there that genuinely works.

Nose bridge height is not a width. A shallow bridge lets a frame slide even when every printed number is right.

Lens depth is rarely printed and it decides whether the frame touches your cheeks when you smile.

Frame curvature varies. A frame with a strong wrap sits differently from a flat one with identical numbers.

So: use the measurements to rule frames out, not to guarantee one in.

Writing it down

Keep the three numbers in your phone. They do not change, and they turn an online frame listing from a guess into a comparison.

`` Face width (cheekbones) : ___ mm Bridge width : ___ mm Temple to temple : ___ mm Reference pair that fits : __ - __ - ___ ``

That last line is the one that will actually do the work.

Pupillary distance, and when it matters

One measurement people meet when ordering prescription lenses, and it is worth knowing even if yours are not prescription.

Pupillary distance (PD) is the gap between the centres of your pupils, typically 54mm to 74mm in adults. For prescription lenses it decides where the optical centre of each lens sits, and getting it wrong induces prism — the lens bends light slightly sideways, your eyes compensate, and you get the strain described in do polarized sunglasses cause eye strain.

For non-prescription sunglasses it matters less, because there is no correction to misalign. But it still tells you something useful: your eyes should sit roughly in the horizontal centre of each lens. If they sit well inboard, the frame is too wide. If they sit outboard toward the hinges, it is too narrow.

Measuring it yourself is awkward and imprecise. Any optician will do it in thirty seconds, and most will write it down for you without charge.

Frequently asked questions

The short version

Measure across your cheekbones; that number sets the frame width you need, and the frame should match it or run a few millimetres wider. Measure your bridge and compare it to the middle number on the arm. Then — better than any of it — find a pair that already fits and copy its three numbers.