Watch lug width explained

How to read the number

A watch with a 20mm lug width takes a 20mm strap at the case end. Many straps taper (for example, 20mm at the lugs to 18mm at the buckle). The lug-width figure always refers to the end that meets the case, not the buckle.

Common widths include 18, 19, 20, 21, and 22mm. Odd sizes exist, so always match the watch rather than guessing from case diameter.

Why it comes up so often

Changing a strap is the fastest way to restyle a watch. Get the lug width wrong and the strap won't fit, or it will stress the spring bars. Lug width also tells you how easy aftermarket straps will be to find. 20mm and 22mm have the most choice by far.