---
title: How to Read Temple Size Markings
description: What the three numbers in a marking such as 52-18-140 mean, where they usually appear, and why a size alone cannot identify a model.
updated: 2026-09-25
---
# How to Read Temple Size Markings

Many frames carry a short size string such as `52-18-140` (on the frame itself a small square usually stands between the first two numbers instead of the first dash). All three numbers are millimeters, and this catalog stores them as three separate fields.

## The three numbers

| Position | Example | Catalog field | Meaning |
|---|---|---|---|
| First | 52 | `lens_width_mm` | Horizontal width of one lens |
| Second (after the square) | 18 | `bridge_width_mm` | Distance between the lenses at the bridge |
| Third | 140 | `temple_length_mm` | Length of the arm |

The square symbol only separates lens width from bridge width. Some pages write the same thing as `52-18-140` or give just the first two numbers, for example `52-22`.

## Where the numbers appear

On a physical frame the marking is usually printed on the inside of a temple arm, often next to a model code and a color code. Online, the numbers may show up in a page title, a size selector or a measurements table. The catalog records where each value came from. For example, the size of a Ray-Ban Original Wayfarer Classic RB2140F variant was read from the page title "(52-22)" ([Ray-Ban US](https://www.ray-ban.com/usa/sunglasses/RB2140F%20UNISEX%20original%20wayfarer%20classic%20low%20bridge%20fit-black/8053672054682)). The maker page did not state a temple length, so that field stays unknown in the catalog rather than being borrowed from another size or listing.

When a page leaves out a number, the field stays null. The catalog never fills it in from a similar frame.

## Why a size does not identify a model

Different models can share the same size. Each of these Ray-Ban pages lists 54-18:

- Original Wayfarer Classic RB2140 ([Ray-Ban US](https://www.ray-ban.com/usa/sunglasses/RB2140original%20wayfarer%20classic-black/805289126584))
- Original Wayfarer Classic RB2140F ([Ray-Ban US](https://www.ray-ban.com/usa/sunglasses/RB2140F%20UNISEX%20original%20wayfarer%20classic%20low%20bridge%20fit-black/805289749752))
- Erika Classic RB4171 ([Ray-Ban US](https://www.ray-ban.com/usa/sunglasses/RB4171erika%20classic-black/8053672495942))

Size letters don't identify a model either. Oakley's US pages show the label "XL (140mm)" for both the Holbrook OO9102 ([Oakley](https://www.oakley.com/en-us/product/W0OO9102?variant=888392335920)) and the Holbrook XL OO9417 ([Oakley](https://www.oakley.com/en-us/product/W0OO9417?variant=888392336491)).

To pin down a product, use the size together with the style code (such as RB2140F or OO9102) and the color or variant code. The size by itself is not enough.

## What the numbers do not tell you

These numbers describe the frame. They don't tell you whether it will fit a particular face, and this site gives no fit guarantees.

## Related

- [/guides/comparing-frame-sizes](/guides/comparing-frame-sizes)
- [/guides/bridge-fit-labels](/guides/bridge-fit-labels)
- [/guides/data-scope-and-sources](/guides/data-scope-and-sources)
- [/docs/resolve_sunglasses.md](/docs/resolve_sunglasses.md)
- [/docs/find_sunglasses.md](/docs/find_sunglasses.md)
- [/docs/data-dictionary.md](/docs/data-dictionary.md)