Guide
What Size Watch Should I Wear?
The right watch size depends on your wrist, but case diameter is only part of it. Lug-to-lug length, thickness and the strap all change how big a watch wears. Measure your wrist, then use the calculator and chart 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 a watch, just above the wrist bone. Keep it snug, not tight. Most adult wrists measure 15–20cm (about 6–8 inches).
Watch size chart by wrist
| Wrist | Case diameter | Lug-to-lug | Watches near the limit |
|---|---|---|---|
| 14–15cm (5.5–5.9in) | 34–38mm | up to ~45mm | Vostok Amphibia 710, Timex Q Timex Reissue 38, Christopher Ward C63 Sealander 39 |
| 15–16.5cm (5.9–6.5in) | 36–40mm | up to ~50mm | Oris Aquis 43.5, Tissot Seastar 1000, Steinhart Ocean One 42 |
| 16.5–18cm (6.5–7.1in) | 38–42mm | up to ~54mm | Seiko Prospex Sumo, Longines Legend Diver 42, Casio G-Shock DW-6900 |
| 18–19.5cm (7.1–7.7in) | 40–44mm | up to ~58mm | Casio G-Shock DW-6900 |
| 19.5–21cm (7.7–8.3in) | 42–46mm | up to ~63mm | — |
The case ranges are the usual guidance, not rules: plenty of people wear bigger or smaller by choice. The lug-to-lug column is the more useful one, because it decides whether the watch overhangs your wrist.
Why lug-to-lug matters more than diameter
Lug-to-lug is the length of the watch from the tip of the top lugs to the tip of the bottom lugs. If it's longer than the flat top of your wrist, the lugs hang over the edges and the watch looks too big, whatever its diameter. A rough rule is that the flat top of the wrist is about 30% of its circumference, so a 17cm wrist suits a lug-to-lug up to about 51mm. That's why a 42mm watch with short lugs can wear smaller than a 40mm watch with long ones. Every watch page on Strap Index lists the lug-to-lug, and our strap length guide explains how the case length changes the strap you need.
Other things that change how big a watch wears
- Thickness. Above about 13mm a watch sits tall and looks bigger; under 10mm it slips under a cuff. Each watch page shows the thickness and which straps balance it.
- Dial and bezel. A thin bezel and a big dial make a watch look larger than a dive watch of the same diameter with a chunky bezel.
- Integrated bracelets. On watches like the Tissot PRX 40 the first link is fixed, so the watch wears longer than its lug-to-lug suggests.
- Lug shape. Lugs that curve down hug the wrist; straight, flat lugs make the watch wear longer.
- The strap. A NATO adds 1–2mm under the case; a thick padded strap makes a watch look bigger, a thin tapered one smaller.
Dress, sport and smartwatches
Dress watches are traditionally smaller and thinner: around 36–40mm suits most wrists. Dive and sports watches usually run 40–44mm. For smartwatches, the case height plays the role of lug-to-lug: compare it with the same 30% rule, and pick the smaller size if you're between two. Band sizes for smartwatches are covered in our Apple Watch, Garmin and Galaxy Watch guides.
Once you've chosen: the strap
The watch's lug width sets the strap size you buy. Look it up in the strap size finder or the size chart.