Scared about ordering glasses online? Not sure how to find out your glasses' frame sizing? Confused about those numbers on the inside of your frames? We've got your answers here. Stick around to find out.

Glasses frame sizing? What do the Numbers Mean?

1. The Numbers on the Frame
2. What is Lens Width?
3. How can I Measure It?
4. What Size is Right for Me?
5. Prescription Glasses at SportRx

Rather than just giving you the short version, Eyeglass Tyler goes in depth on how to understand the measurement information on your glasses. We cover how to differentiate between model information and frame measurements, explain the different glasses frame sizing systems, and help you figure out how you can measure your glasses yourself. By the end of this article, you'll know how to find out which frame (and its' size) is right for you.

The Numbers on the Frame

Frame measurements are pretty consistent across brands, indicated by numbers on the inside of the temples or possibly on the nose bridge if your frame is made of metal.

The size of your frame will always be measured in millimeters. You'll see a number such as 48, followed by a square symbol and a smaller number, such as 22. Last will be a larger number, such as 138. See it on the Maui Jim Koko Head below.

Maui Jim Koko Head measurements

Shop Maui Jim Koko Head

That first number refers to the lens width at its widest point, while the second number is the bridge width, or the distance between lenses at its most narrow. Finally, the last number is the temple length. Tyler points out that the temple length isn't super important when determining whether the glasses will fit you.

As for model information, most brands will have some form of acronym followed by a code. Maui Jim, for example, writes their models as MJ followed by a four-digit number. On the other hand, some brands will simply print the frame name, like the Oakley Holbrook. You may also see a dash and some other numbers, which usually refer to the color code.

What is Lens Width?

Lens width is measured from left to right at the widest point in the lens. Between a 52 and 54 eyesize, the 54 will have a wider lens so the whole frame will be wider too. The lens will also be a little taller to preserve the shape. The bridge and temple measurements will usually remain the same.

Ray-Ban in particular makes different eyesizes so you can rock the same look whether you have a big head or not. Consider the New Wayfarer, which comes in three eyesizes of 52, 55, and 58.

Ray-Ban RB2132 New Wayfarer sunglasses in light havana with brown b-15 lenses set on white background

Ray-Ban RB2132 New Wayfarer in Light Havana with B-15 Lenses

Shop Ray-Ban New Wayfarer (52 Eyesize)

Shop Ray-Ban New Wayfarer (55 Eyesize)

Shop Ray-Ban New Wayfarer (58 Eyesize)

These sunglasses may all look identical in pictures, but they fit three head sizes!

How Can I Measure It?

You may not know what the measurements of your glasses are. Either the manufacturer didn't print the numbers (which is uncommon) or they rubbed off over time (which is common). Don't despair! You can just grab a ruler with millimeters and measure the lens at the widest part to find out.

Tyler also points out that it's not necessary to measure the bridge width, since it only indicates the shortest distance between the lenses. This measurement doesn't dictate how well the frame will fit your nose bridge.

Measuring lens width gets trickier if you have a curved frame. If this is the case, SportRx has a great solution: Measure temple to temple. This accommodates for the curved frame and gives a better idea of what size glasses will fit you best. We call this measurement the SFW and have a handy video on how to find yours here: Introducing the SportRx Frame Width.

What Size is Right for Me?

The best way to figure this out is to check the numbers on your glasses so you have an idea of what works for you. And chances are, you already know roughly what head size you have.

If you're not sure, you're probably a medium. Most frames are made to fit that happy medium, so you may not have had difficulty finding the right size glasses for you.

Otherwise, here's a frame of reference:

  • Small to Medium: 50-52mm
  • Medium to Large: 52-55mm
  • Large to XL: 55+mm

To reuse our New Wayfarer example from earlier, the 52 eyesize is a medium fit, the 55 is a large fit, and the 58 is an XL fit. Depending on your personal sense of style, you may even fit two of these but prefer one over the other.

Another thing to note is that frame style can affect lens width as well. For example, a frame with a high base curve like the Maui Jim Kanaio Coast will have a different lens width than the more casual Maui Jim Red Sands. But they both might look great on you. Lens width gets a little trickier when you add these extra variables, which is why we recommend you check out our SportRx Frame Width video for a more standardized frame fit.

Even if you do end up getting the wrong size, thanks to SportRx's See Better Guarantee, you'll never have to be stuck with ill-fitting frames.

Prescription Glasses at SportRx

Need prescription glasses? Done. When you shop with us, you’ll find video guides and tooltips throughout the build process as you customize the perfect pair. An answer to all your questions is at your fingertips, and if you want to chat with an expert, Contact Us. We’ll put you in touch with one of our friendly in-house opticians who can help you build your prescription glasses.

Ditch risky online shopping with the See Better Guarantee. Try your glasses or sunglasses for 45 days. If you’re not satisfied, send them back. Get a full refund, exchange, or credit towards a better pair. And return shipping? Covered. Get your pair of prescription glasses at SportRx today!

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