How to Choose the Right Frame Size — Your PD, Width & Bridge Measurements
Frame measurements can narrow the options, but they do not guarantee fit. Start with the dimensions of a pair that already feels comfortable, compare the retailer's complete frame specification and use professional optical measurements when required. This page does not claim a frame-order or fit test.
The 3 Frame Measurements — Reading the Numbers Inside Your Temple
Look at the inside of any glasses arm. You'll see three numbers, like 52 □ 18 140. Here's what each means:
Lens Width (e.g. 52mm)
The horizontal width of one lens at its widest point. Compare it with a known comfortable frame, but also check total frame width, lens shape and rim thickness. The same lens width can fit differently across designs.
Bridge Width (e.g. 18mm)
The printed distance between the lenses. Compare the number and the bridge design with a known frame. Keyhole, saddle and adjustable-pad bridges can sit differently even when the listed width is the same.
Temple Length (e.g. 140mm)
The arm length from hinge to tip. Use the number on a comfortable frame as the reference and check the retailer's adjustment guidance. Temple shape and bend position also affect how the frame sits.
How to Measure Your PD (Pupillary Distance) — 3 Methods
Method 1: Use a Professional Measurement
Ask an optometrist or dispensing optician for the measurements needed for the selected lens design. Record whether the value is binocular or monocular and whether additional fitting heights are required.
Method 2: Review an Online Tool's Instructions
If a retailer offers a measurement tool, follow its current instructions and read its limitations. An online result is not assumed to match a professional measurement, especially for stronger or multifocal prescriptions.
Method 3: Treat Self-Measurement as a Cross-Check
A ruler method can be repeated as a rough cross-check, but viewing distance, head position and alignment can change the result. Do not rely on an uncertain self-measurement when the prescription or lens design requires precise fitting data.
Frame-Fit Decision Fields
| Input | What to compare | Limitation | Next action |
|---|---|---|---|
| Known comfortable frame | Total width, lens width, bridge, temple and lens height | Materials and geometry can change the fit | Shortlist frames with closely comparable dimensions |
| Retailer specification | Complete dimensions, bridge style and adjustment options | A missing total width makes comparison less certain | Ask the retailer for the missing measurement |
| Prescription requirements | PD, fitting height and lens-design limits | Strong or multifocal prescriptions may need extra measurements | Confirm with an eye-care professional |
| Fit and return policy | Adjustment, remake, exchange and custom-lens exclusions | A return window does not mean every prescription order qualifies | Save the applicable policy before ordering |
Virtual Try-On: What It Can and Cannot Answer
| Tool type | Useful for | Does not establish | Verification step |
|---|---|---|---|
| Photo overlay | Comparing colour and general shape | Physical scale, bridge contact or comfort | Check dimensions against a known frame |
| Live webcam preview | Viewing several styles quickly | Lens requirements or all fit pressure points | Review specification and adjustment options |
| App-based AR | Approximate styling and proportions | A guaranteed real-world fit | Read calibration instructions and fit policy |
| Store or home try-on, if offered | Assessing an unglazed frame's physical fit | Final prescription-lens vision or weight | Confirm eligibility and prescription return terms |
Before ordering, compare all available dimensions with a known comfortable frame and save the policy that applies to prescription lenses. Confirm adjustment, remake, exchange, refund and return-postage terms; a general return headline may have custom-lens exclusions.
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