Guide
Watch Strap Length & Wrist Fit Guide
Width is only half of strap sizing. Length decides whether the buckle sits in the right place, and the watch's lug-to-lug decides whether the case suits your wrist at all. Measure once, then use the calculator below.
Step 1: measure your wrist
Wrap a soft tape measure, or a strip of paper you then lay against a ruler, around your wrist where you wear the watch, usually just above the wrist bone. Keep it snug but not tight. Most adult wrists are between 15 and 20cm.
Step 2: understand how strap lengths are listed
Two-piece straps are usually listed with two numbers, such as 120/75mm: the long piece with the holes, then the short piece with the buckle. Sizes vary by maker, but as a rough guide:
| Length | Typical pieces | Roughly suits wrists of |
|---|---|---|
| Short | 110/70mm | 14–16cm |
| Standard | 120/75mm | 16–19cm |
| Long | 130/80mm | 19–21cm |
| Extra long | 140/85mm+ | 21cm and up |
Always check the maker's own size chart: two “standard” straps can differ by a centimetre.
Why the watch itself changes the strap length you need
The watch case takes up part of your wrist. Roughly, wrist = short piece + the part of the long piece up to the hole you use + the watch's lug-to-lug. So a watch with a long lug-to-lug needs less strap. On the same wrist, a 50mm lug-to-lug diver may sit best on a shorter strap than a 37mm Casio F-91W.
Lug-to-lug: will the watch overhang?
Lug-to-lug is the tip-to-tip length of the case. If it's longer than the flat top of your wrist, the lugs overhang the sides and the watch looks and feels too big, whatever its diameter. A common rule of thumb is that the flat top of the wrist is roughly 30% of your wrist circumference:
| Wrist | Comfortable lug-to-lug up to about |
|---|---|
| 15cm | 45mm |
| 16cm | 48mm |
| 17cm | 51mm |
| 18cm | 54mm |
| 19cm | 57mm |
| 20cm | 60mm |
Wrist shape varies, so treat this as a starting point. Flat, wide wrists can wear more; round, narrow ones less. Every watch page on Strap Index lists the lug-to-lug, and the calculator above uses the 57 watches in our index with a published lug-to-lug.
NATO and one-piece strap lengths
NATOs are a single long piece, typically 260–285mm. The excess tucks into the keepers, so one length fits a wide range of wrists. On wrists under about 15cm a standard NATO can leave a long tail. Look for “short” NATOs around 240mm, or try a single-pass strap.
Bracelets
Metal bracelets are sized by removing links, then fine-tuned with micro-adjust holes in the clasp. If you're between sizes, half-links (where available) help. Bracelets need end-links made for your exact model.