The Watch Strap Guide

Lug width is the gap between the lugs where the strap sits, measured in millimetres and almost always an even number — 18, 20, 22. Measure it with calipers or a ruler across the gap.

A strap one millimetre too narrow will slide and look wrong. One millimetre too wide will not fit at all. This is the only measurement you cannot fudge.

Leather is the default for dress and vintage-styled watches. It shapes to the wrist within a fortnight and dies quickly if you swim in it. Expect two to three years of daily wear.

Steel bracelets suit sports watches and add weight and formality. A tapering bracelet with solid end links is the mark of a good one; hollow links rattle.

Rubber is the correct answer for heat, water and exercise. Modern FKM rubber does not smell or discolour the way older silicone straps did.

NATO straps pass under the caseback, so the watch cannot fall off if a spring bar fails. They add a few millimetres of height and cost almost nothing, which makes them the best way to experiment.

You need a spring bar tool, which costs about ten dollars. Slide the forked end between the strap and the lug, compress the spring bar, and angle the strap out. Reverse to install, then tug firmly to confirm both ends are seated.

Quick-release spring bars have a small lever you slide with a fingernail — no tool at all. Many watches now ship with them, and aftermarket sets are inexpensive.

Work over a soft cloth. The most common damage in strap changes is a slipped tool gouging the lug.