The short answer
Measure your wrist just above the wrist bone. Most men wear a 40 to 42 mm case and most women 30 to 36 mm. A gem-set bezel wears larger than its diameter, so choose the smaller size when you are between two, and check the lug-to-lug span against the flat of your wrist: that is the measurement that decides fit.
| Wrist circumference | Men’s case | Women’s case |
|---|---|---|
| Under 15 cm (5.9 in) | 36–38 mm | 26–32 mm |
| 15–16.5 cm (5.9–6.5 in) | 38–40 mm | 32–36 mm |
| 16.5–19 cm (6.5–7.5 in) | 40–42 mm | 34–38 mm |
| Over 19 cm (7.5 in) | 42–46 mm | 36–38 mm |
Measuring your wrist
- Wrap a strip of paper or a soft tape around your wrist just above the wrist bone, where a watch sits.
- Draw it snug but not tight; you should be able to slide a fingertip beneath it.
- Mark where it overlaps, lay it flat, and measure to the mark.
- Measure at the end of the day, when your wrist is at its largest, and measure twice.
Diameter, lug-to-lug and thickness
- Case diameter is the width across the dial, excluding the crown. It is the headline figure on most listings, and the first to check.
- Lug-to-lug is the span from the tip of the upper lugs to the tip of the lower. It decides whether the watch overhangs your wrist, and it is the most reliable predictor of fit.
- Thickness is how tall the case stands off the wrist. It decides whether the watch slides beneath a shirt cuff.
The rule for lug-to-lug is simple: it should not exceed the flat width of your wrist. Look straight down at the watch; if the tips of the lugs pass the edges of your wrist, the case is too large, whatever its diameter. Many gem-set cases have short, integrated lugs that flow into the bracelet, and they wear smaller than their diameter suggests — when a listing gives lug-to-lug, trust it over diameter.
For thickness, under 11 mm slips beneath a buttoned cuff; 11 to 14 mm rides at the cuff line and stays visible; above 14 mm the watch sits on top of the cuff by design. Automatic movements tend to make a case a little thicker than quartz; our guide to automatic and quartz movements explains why.
Why gem-set watches wear larger
Stones catch the light, and light draws the eye outward. A bezel set with stones reads as part of the dial, so a 40 mm gem-set watch can look as large as a 42 mm plain one. The effect is strongest on a fully set case, where no polished metal marks the edge. That is why we suggest the lower half of the range for gem-set pieces, and the smaller of two sizes when in doubt.
Dress and sport sizing
A dress watch is sized for discretion: a modest diameter and a slim case, so it disappears beneath a cuff until the light finds it. See men’s dress watches and women’s dress watches. A sport watch on a steel bracelet can take the upper half of your range, because the bracelet carries the case visually and the watch is meant to be seen.
Band width and bracelet fit
Band width — the width of the strap or bracelet where it meets the case — shapes the watch’s proportion as much as its diameter. As a rule, the band is roughly half the case diameter: about 20 to 22 mm on a 40 to 44 mm case, 14 to 18 mm on a women’s watch. A tapering band, wider at the lugs and narrower at the clasp, makes a larger case sit more comfortably.
A metal bracelet should allow a finger to slide beneath it, and should not slip over the wrist bone. Most link bracelets can be shortened by a jeweler by removing links; if yours sits between two lengths, choose the looser fit in summer, when wrists swell a little in warmth.
Buying without trying on
Measure a watch you already own and like, and compare its diameter, lug-to-lug and thickness with the listing. Cut a paper circle of the listed diameter and hold it to your wrist; it is surprisingly telling. And if the watch is not right when it arrives, you have 30 days from delivery to return it — our returns page sets out how.
Proportion beyond the wrist
Consider your build and your wardrobe as well as your wrist. A larger frame carries a larger case; a slim frame looks sharper with a smaller one. Tailored clothing favors a restrained watch; open collars and rolled sleeves allow more presence. The chart gives you a range, and these considerations tell you where in it to stand.