How to Read Eyeglass Frame Sizes: A Simple Fit Guide

By Mara Lin, Le Seven Fit & Measurement Editor

Frame numbers are a useful starting point when you are shopping online. They describe the lens width, bridge width and temple length—not a promise of fit—so use them alongside how your current glasses sit on your nose, ears and face.

What do the numbers on glasses mean?

Most frames show three measurements in millimetres, often written like 52□18–140: lens width, bridge width and temple length. A fourth measurement, lens height, can also be helpful when comparing shapes.

Start with a pair that already feels good

Look inside the temple of your best-fitting frame and note its numbers. Use them as a comparison point, then consider the shape: a deep square lens can feel larger than a narrow rectangular lens with the same width.

Check the fit points that matter

• Bridge: the frame should rest securely without pinching or sliding constantly.
• Lens width: your eyes should sit comfortably behind the lenses, not crowded near the outer edge.
• Temple length: temples should reach your ears without pressing or leaving the frame loose.

Use the product page, not numbers alone

Compare the listed dimensions, photos and shape with your reference pair. If you are ordering prescription glasses, also review how to measure your PD before checkout. For a starting point, explore our prescription glasses collection.

Quick FAQ

Are bigger frame numbers always wider?

Usually, but the overall width and shape matter too. Compare like-for-like frame styles whenever possible.

What if I am between sizes?

Prioritize the bridge and overall width of the pair you already wear comfortably, then use the product photographs and dimensions to make the final call.