Tool
Wrist fit calculator
Case diameter gets the attention, but lug to lug decides whether a watch overhangs. Enter your wrist and the watch's two numbers to see how it is likely to sit.
Short answer
The flat top of a wrist is roughly 30% of its circumference wide. A lug to lug at or below that usually fits, up to about 32% is borderline, and more is likely to overhang. For case diameter, a 6.5 to 7.0 inch wrist commonly suits 38 to 42 mm.
Check a watch against your wrist
Measure your wrist where you wear the watch, just above the wrist bone, with a soft tape or a strip of paper you then lay on a ruler. Take the case diameter and lug to lug from the maker's spec sheet or the listing.
Fit passport
Fits
The lugs should sit inside the flat top of your wrist.
- Wrist
- 7.00 in / 178 mm
- Flat top (30%)
- about 53 mm
- Edge (32%)
- about 57 mm
- Lug to lug
- 48 mm
- Usual case size
- 40 to 44 mm
- Your case
- 40 mm, in range
A common guideline, not a rule. Case thickness, how the strap or bracelet curves, and personal taste also matter.
Why lug to lug matters more than diameter
Case diameter is measured across the case, usually without the crown. Lug to lug is the length of the watch from the tip of the top lugs to the tip of the bottom lugs, and it is the number that has to fit across the flat top of your wrist. Two 40 mm watches can differ by 5 mm or more in lug to lug.
The flat top of a wrist is roughly 30 percent of its circumference wide. When the lugs end inside it, the watch sits flat and looks in proportion. When they end past it, the lugs float over the sides of the wrist, which is what people mean by overhang.
Common case size by wrist
| Wrist circumference | Common case diameter |
|---|---|
| Under 6.0 in (152 mm) | 34 to 38 mm |
| 6.0 to 6.5 in (152 to 165 mm) | 36 to 40 mm |
| 6.5 to 7.0 in (165 to 178 mm) | 38 to 42 mm |
| 7.0 to 7.5 in (178 to 191 mm) | 40 to 44 mm |
| 7.5 to 8.0 in (191 to 203 mm) | 42 to 46 mm |
| Over 8.0 in (203 mm) | 44 mm and up |
Thickness changes how a watch wears as well: a 14 mm thick case sits high and catches shirt cuffs, while a 10 mm case slides under them. More on measuring and bracelet sizing in fit and sizing.