What size NATO strap do I need?

Match the strap width to your watch's lug width, the gap between its lugs, usually 18, 20 or 22 mm. A strap even 1 mm too wide won't fit; 1 mm too narrow will slide around.

Why is it called a NATO strap?

The design comes from a British Ministry of Defence issue strap from the 1970s. The name comes from the NATO Stock Number it was catalogued under, not from NATO itself designing it.

Does a NATO strap make a watch sit higher?

Yes. The strap runs under the case in two layers, adding a few millimeters of height. On a thick watch that can matter; a single-pass strap avoids it.

NATO Straps: What They Are, Sizing and Fit

NATO straps: what they are and how to size one

A NATO strap is a single piece of nylon webbing that threads under the watch, through both spring bars, and folds back through a second keeper. It's cheap, tough, and if one spring bar fails the watch stays on your wrist.

NATO, Zulu and single-pass

NATO: a long strap plus a short second layer that runs under the case. Secure, but it adds thickness under the watch.
Zulu: the same idea in heavier webbing with rounded hardware, usually with more keepers. Bulkier and better suited to big dive watches.
Single-pass: one layer of webbing threaded through the spring bars. Thinner, so the watch sits lower, but without the fail-safe of the second layer.

Getting the width right

The strap's width has to match your watch's lug width. Across the 317 watches in the almanac with a known lug width, the most common are 20 mm, 22 mm, 21 mm. Look your watch up to check, or browse every watch by lug width.

Getting the length right

NATO straps come in fixed lengths, typically between about 250 and 300 mm. Too long leaves a tail that needs tucking under the keepers. A small wrist usually wants a shorter strap, or a single-pass strap, so the excess doesn't bunch.

How a NATO changes the fit

Because the strap passes straight across the lugs instead of curving down from them, a NATO can make a watch feel slightly larger and sit higher on the wrist. If a watch is already near the edge of your wrist on our fit finder, a single-pass strap or a bracelet will wear smaller.

Prefer metal? See how to resize a bracelet.

Questions

What size NATO strap do I need?: Match the strap width to your watch's lug width, the gap between its lugs, usually 18, 20 or 22 mm. A strap even 1 mm too wide won't fit; 1 mm too narrow will slide around.
Why is it called a NATO strap?: The design comes from a British Ministry of Defence issue strap from the 1970s. The name comes from the NATO Stock Number it was catalogued under, not from NATO itself designing it.
Does a NATO strap make a watch sit higher?: Yes. The strap runs under the case in two layers, adding a few millimeters of height. On a thick watch that can matter; a single-pass strap avoids it.