Eyeglasses
Eyeglass Frame Measurements Explained
The small numbers inside a temple help compare frames but do not fully describe case fit.
Lens width, bridge width and temple length describe parts of a frame. They do not directly give total frame width, case depth or optical fitting measurements.
Read the three commonly printed numbers
A marking such as 52–18–140 usually means lens width, bridge width, and temple length in millimeters.
Compare frames without ignoring their shape
Compare a comfortable existing pair while allowing for different bridge shapes, hinges, and rim thickness.
Measure folded dimensions for storage separately
Measure total width, maximum height, and folded depth separately for a reliable case choice.
Read an example without overinterpreting it
A marking such as 52–18–140 commonly means a 52 mm lens width, an 18 mm bridge measurement and a 140 mm temple length. These are an example, not a recommended size. Some frames include other model or color numbers, so confirm unfamiliar markings with the maker.
It can be tempting to double lens width and add bridge width to estimate total width. That omits rim thickness, hinge extensions and decorative corners. Use the assembled frame’s actual outside width when comparing a case.
Frame measurements and case measurements differ
Keep these two lists separate when shopping.
| Number | Describes | Does not establish |
|---|---|---|
| Lens width | A lens opening dimension | Total outer frame width |
| Bridge width | The marked bridge dimension | Comfort for every bridge shape |
| Temple length | Length of an arm | Folded case depth |
| Folded width × height × depth | The pair’s storage envelope | Pupillary distance or prescription fit |
Use a familiar pair as a starting reference
Numbers from a comfortable existing pair can narrow a frame search, but another design with the same markings may sit differently. Bridge shape, arm curvature and hinge placement all matter. For storage, measure the final adjusted pair instead of buying a case from the printed numbers alone.
Questions about eyeglasses
Is temple length the same as the case’s interior length?
No. The arm folds into the overall pair, and its curvature affects depth. Measure the complete folded shape.
Does a bridge marking tell me my pupillary distance?
No. It is a frame dimension, while pupillary distance concerns the wearer. Obtain the required optical measurements through a suitable professional or retailer process.
Use this guide to evaluate fit and specifications. This is a retailer link, not a claim that we have tested every product.
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