Watch Size Guide: Case Diameter, Lug-to-Lug and Strap Size for Your Wrist
For anyone choosing a watch online, where a few millimeters of case size can mean the difference between a watch that sits flat and one that overhangs the wrist. All case figures are in millimeters, as watchmakers publish them.
A watch's size is its case diameter in millimeters, measured across the case without the crown. Most men's watches are 38 to 44 mm and most women's 28 to 36 mm. A 6.5 to 7 in (16.5 to 17.8 cm) wrist usually suits 38 to 42 mm; the deciding measurement is lug-to-lug length, which should not exceed the flat top of your wrist.
- Men's typical
- 38-44 mm
- Women's typical
- 28-36 mm
- Common lug width
- 18, 20, 22 mm
- Average wrist
- 6.9 in M, 6.1 in F
On this page
Watch size chart by wrist circumference
Measure your wrist just above the wrist bone, then use the range below as a starting point for a round, traditional watch. The ranges are proportion guidelines, not a standard.
| Wrist circumference | cm | Case diameter that sits well | Lug-to-lug up to about |
|---|---|---|---|
| Under 6 in | Under 15.2 | 28 to 36 mm | 42 mm |
| 6 to 6.5 in | 15.2 to 16.5 | 34 to 39 mm | 45 mm |
| 6.5 to 7 in | 16.5 to 17.8 | 38 to 42 mm | 48 mm |
| 7 to 7.5 in | 17.8 to 19.1 | 40 to 44 mm | 50 mm |
| 7.5 to 8 in | 19.1 to 20.3 | 42 to 46 mm | 53 mm |
| Over 8 in | Over 20.3 | 44 mm and up | 55 mm and up |
In the ANSUR II body-measurement survey of US Army personnel, the average wrist was 6.9 in (176 mm) for men and 6.1 in (155 mm) for women. That places the average man in the 38 to 42 mm band and the average woman in the 34 to 39 mm band.
Case size categories
| Diameter | Inches | Category | Typical watches |
|---|---|---|---|
| 22 to 30 mm | 0.87 to 1.18 in | Small women's | Dress and jewelry watches |
| 31 to 35 mm | 1.22 to 1.38 in | Women's standard; small vintage men's | Classic women's watches, 1950s to 1970s men's watches |
| 36 to 38 mm | 1.42 to 1.50 in | Mid size | Classic men's dress watches, unisex |
| 39 to 42 mm | 1.54 to 1.65 in | Men's standard | Sports, dive and chronograph watches |
| 43 to 46 mm | 1.69 to 1.81 in | Large | Pilot, dive and sports watches |
| 47 mm and up | 1.85 in and up | Oversized | Large pilot and tool watches |
Some reference points with published diameters: the Rolex Submariner is 41 mm, the Rolex Datejust is made in 36 and 41 mm, and the Omega Speedmaster Moonwatch Professional is 42 mm. The Casio F-91W digital watch measures 38.2 × 35.2 × 8.5 mm, and the square Casio G-Shock DW-5600 is 48.9 × 42.8 × 13.4 mm.
Lug-to-lug: the measurement that decides fit
Lug-to-lug is the distance from the tip of the top lugs to the tip of the bottom lugs. If it is longer than the flat top of your wrist, the lugs hang past the edges and the strap sticks out instead of curving down. Two 40 mm watches can differ by 6 mm or more in lug-to-lug.
- Measure your wrist's flat top. Lay a ruler across the top of the wrist, where the watch sits, and note the width of the flat area from one side to the other.
- Find the watch's lug-to-lug. Many makers list it; enthusiast reviews nearly always do. For a typical round watch it runs about 1.15 to 1.25 times the case diameter, so a 40 mm watch is around 46 to 50 mm.
- Compare. A lug-to-lug equal to or a few millimeters shorter than the flat width sits well. Curved, short lugs make a large case wear smaller.
Draw the case diameter and lug-to-lug to scale on paper, cut it out and lay it on your wrist. It is a quick way to judge a watch you cannot try on.
Case thickness
| Thickness | Inches | Typical watches | Under a shirt cuff |
|---|---|---|---|
| Under 8 mm | Under 0.31 in | Thin dress watches, quartz | Slides under easily |
| 8 to 11 mm | 0.31 to 0.43 in | Everyday automatics, field watches | Fits under most cuffs |
| 11 to 13 mm | 0.43 to 0.51 in | Dive and sports watches, many chronographs | Snug under a dress cuff |
| 13 to 16 mm | 0.51 to 0.63 in | Professional divers, G-Shocks, smartwatches | Needs a wider cuff |
| Over 16 mm | Over 0.63 in | Deep-rated divers, complicated chronographs | Usually worn over the cuff |
Thickness also sets the size of the storage you need: a deep 15 mm diver may not fit under the lid of a slim watch box.
Lug width and strap sizes
Lug width is the inside distance between the lugs, and the strap must match it. Larger cases usually have wider lugs, roughly half the case diameter.
| Case diameter | Usual lug width |
|---|---|
| 26 to 32 mm | 12 to 16 mm |
| 34 to 38 mm | 18 mm |
| 38 to 41 mm | 19 to 20 mm |
| 42 to 45 mm | 21 to 22 mm |
| 46 mm and up | 22 to 24 mm |
Strap length
A two-piece strap is listed by its two pieces, the long (holes) side first: for example 120/75 mm. Common sizes are short (about 110/70 mm) for smaller wrists, standard (about 120/75 mm) for most wrists in the 6.5 to 7.5 in range, and long (about 130/80 mm) for larger wrists. Exact fit depends on the case's lug-to-lug, so compare with a strap that already fits you before ordering.
Metal bracelets
Metal bracelets are shortened by removing links, usually from both sides of the clasp to keep the case centered. Many clasps also have micro-adjust holes for small changes. Wear a metal bracelet slightly looser than a strap, with room for a fingertip, because the wrist swells during the day. The same allowance logic appears in the bracelet size chart.
Why a watch wears larger or smaller than its size
- Choosing by diameter alone. Lug-to-lug, thickness and bezel style all change how large a watch wears. A thin bezel with a big dial looks larger than the same diameter with a wide dive bezel.
- Confusing smartwatch sizes. Smartwatch sizes describe a rectangular case, often its height. See the smartwatch size guide.
- Forgetting the dominant hand. Most people wear a watch on the non-dominant wrist, which is often slightly smaller.
- Ignoring rings and cuffs. A thick watch on the same hand as a wide wedding band is fine; a thick watch under a tight shirt cuff is not.
When storing several watches, each needs its own cushion to avoid scratches; see the watch box size guide, or the jewelry box guide for combined storage.
Frequently asked questions
Is a 40 mm watch big?
No. 40 mm (1.57 in) is a medium size and suits most men's wrists from about 6.25 to 7.5 in. It is large on a typical woman's wrist of about 6 in, where 34 to 38 mm is closer to average.
What size watch should a man with a 7 inch wrist wear?
A 7 in (17.8 cm) wrist suits 39 to 42 mm cases, with a lug-to-lug length up to about 48 to 50 mm. Divers' and sports watches up to 44 mm also work if their lugs curve down.
What is a good watch size for women?
For a wrist of about 6 in (15.2 cm), 28 to 34 mm gives a classic proportion, and 34 to 38 mm suits a sportier, larger look. Rectangular watches are measured by width and length, for example 22 × 30 mm.
Does the crown count in the watch size?
No. The published diameter excludes the crown, which adds roughly 3 to 5 mm on the right side. Crown guards on dive watches can add more.
What lug width should my strap be?
Exactly the distance between the lugs, measured in millimeters with calipers or a ruler. Most watches use even sizes such as 18, 20 or 22 mm. A strap 1 mm too narrow rattles; 1 mm too wide will not fit.
Are smartwatch sizes the same as watch sizes?
Not quite. Apple Watch sizes give the case height, not a diameter, and smartwatch cases are thicker than most analog watches. Compare sizes in the smartwatch size guide.