How to measure glasses frame width at home

Total frame width is the distance across the whole front of a pair of glasses. It is the first size number to compare when glasses feel too tight or too loose, and it is usually not printed on the frame. Here are three ways to find the number that suits you.

Get my frame width range — free

1. Measure a pair that fits you

1. Choose glasses that feel right at the sides of your head: not pressing, not loose.
2. Lay them on a table with the front facing you and the arms open.
3. Hold a millimeter ruler across the front and measure from the outermost point on the left to the outermost point on the right, at the widest place. Include hinges or decoration that stick out.
4. Write the number down in millimeters. One inch is 25.4 mm.

Compare it with the “frame width” or “total width” a store publishes. A few millimeters either way is close. A frame much narrower than yours is likely to press on your temples.

2. If the store prints only three numbers

The marking inside the arm, such as 52-18-140, gives lens width, bridge width and arm length. Some online size calculators add lens + bridge + lens (52 + 18 + 52 = 122 mm) and call that the frame width. That sum leaves out the rims and hinges at both ends, so it comes out too small.

We checked this against our own catalog. Of its 113 eyeglass frames, 109 have a total width published by the store. Every one of those 109 is wider than its lens + bridge + lens: by 2 to 22 mm, and by 13.4 mm in the middle of the range.

The same three numbers can also belong to quite different frames. Two frames in our catalog are both marked 51-20-140, and they measure 130 and 143 mm across the front. Use the sum only as a rough lower limit, and look for a published total width. Our guide to the three numbers explains each one.

3. No pair that fits? Use a face scan

FitMyFace's free scan measures your face on your phone. It uses the colored part of your eye, the iris, as a ruler. In adults the iris is close to 12 mm across on average, but it varies from person to person, so every number the scan gives is an estimate.

After the scan you see a best frame width, a range of total widths to look for at any store, and an estimate of the distance between your pupils (PD). A button copies the numbers so you can shop anywhere. The finder also ranks real frames from 9 stores, with closeness to your width counting most.

Approximate, not an eye exam: the scan and the on-face preview are approximate. For prescription lenses, use the PD from your optician or prescription, not a selfie estimate, and let an optician confirm the final fit.

Questions

Is lens width the same as frame width?

No. Lens width is one lens opening. Total frame width covers both lenses, the bridge, and the rims and hinges at the outer edges.

What if my number falls between two sizes?

Try both on your face if you can, and check pressure at the temples and whether the frame slides when you look down. An optician can adjust the arms and nose pads.

Is my photo uploaded?

Not for the glasses scan: it runs on your device. The optional AI previews (hair and glasses) send a photo to Cloudflare; your consent is the one "I agree" on the scan screen, and a switch on the results turns them off. FitMyFace is for adults 18 and over and is not available in Illinois.

Scan my face for a width range

Head wider than most frames? Read glasses for big heads.

Once you have your number, compare it with the catalog's frames grouped by total width, from under 130 mm to 150 mm and wider.