Glasses Size Guide — How Frames Should Fit
Glasses Size Guide — How Frames Should Fit
Frame size matters more than people think. The right size sits comfortably for hours; the wrong size slides down your nose, pinches your temples, or makes your face look out of proportion. This guide explains how to read the numbers printed on your current frames and how to find a new pair that fits.
The three numbers on every frame
Look on the inside of one of the temple arms. You’ll see three numbers, usually printed in this format:
52 □ 18 - 140
These are all measured in millimetres:
- 52 — lens width (across the widest part of one lens)
- 18 — bridge width (the gap between the two lenses, where the frame sits on your nose)
- 140 — temple length (the arm that goes back over your ear)
You may also see a fourth number for lens height (e.g. 38) printed separately.
Typical adult frame sizes
| Size category | Lens width (mm) | Total frame width (mm) |
|---|---|---|
| Small | Up to 49 | Up to 125 |
| Medium | 50–52 | 126–135 |
| Large | 53–55 | 136–145 |
| Extra large | 56+ | 146+ |
How to find your size
Method 1 — Use a frame you already own
Find a pair that fits well and read the numbers from the inside of the arm. Look for new frames within 2 mm of those measurements.
Method 2 — Measure your face
Stand in front of a mirror and measure the width of your face from temple to temple in millimetres. This roughly equals the total frame width you should look for.
Method 3 — The credit card test
Hold a standard credit card (85.6 mm wide) horizontally between your eyebrows. If your face is wider than the card, you’ll usually wear medium or large frames. Narrower than the card suggests small frames.
Common fit problems
- Glasses slide down your nose — bridge is too wide, or temples need adjusting
- Pinching at temples or behind ears — frame is too narrow, or temple length is too short
- Eyes don’t align with the lens centre — lens width is too small or too large for your face
- Marks on the bridge of your nose — weight of the frame and lens is too heavy; consider a higher-index lens
Frequently asked questions
What if there’s no current pair to measure?
Use the credit card test for a quick estimate, or message us with a head-on photo and we’ll suggest sizes that should fit.
Are designer frame sizes different from regular frames?
The numbering is the same across all brands. Some designer brands run slightly larger or smaller than the printed size suggests — we note this in product descriptions where relevant.
Can I adjust frames after I receive them?
Yes. Most plastic frames can have the temple angle adjusted by warming gently. Most metal frames can be adjusted at the temples and nose pads. We don’t recommend doing this yourself — a registered optician can adjust your glasses for free at any practice.
Will my prescription affect frame choice?
Stronger prescriptions look thicker in larger frames. If your prescription is above ±4.00, smaller frames or higher-index lenses (1.67 or 1.74) keep the lens looking thin.
