Watch Band Size Chart, Lug Widths by Case Size and Brand

What watch band size do I need?

The one that matches your watch's lug width. Bands and straps are sized the same way, so this goes for a leather strap as much as for a metal bracelet. The lugs are the four arms on the case that hold the band, and the lug width is the gap between them, in millimeters. The end of the band has to be exactly that wide: a wider one won't go in, and a narrower one leaves a gap on each side and shifts around.

So start with the watch; your wrist only matters for the length. The quickest answer is the "Band Width" line in the spec table of the watch's Amazon listing; with the watch in hand, a ruler or the width stamped on the back of most bands settles it. Our guide to changing a watch strap covers the measuring and the swap, and our glossary has a page on lug width.

Can't measure, or buying the band before the watch arrives? The chart below gives the most likely width for your case size. We built it from the Bravery Watch catalog: the 1,588 watches on Amazon US whose listing gives a usable band width, 1,267 of them round with a listed case size.

Watch band size chart by case size

Case size	Round watches	Most common band width	Also common
Under 30 mm	81	12 mm (48%)	14 mm (19%), 16 mm (14%)
30 to 33 mm	90	14 mm (34%)	16 mm (30%), 12 mm (13%)
34 to 35 mm	50	16 mm and 18 mm (24% each)	12 mm (20%), 20 mm (16%)
36 to 37 mm	104	18 mm (51%)	16 mm (13%), 14 mm and 20 mm (10% each)
38 to 39 mm	166	20 mm (54%)	18 mm (19%), 21 mm (7%)
40 to 41 mm	268	20 mm (50%)	22 mm (19%), 21 mm (14%)
42 to 43 mm	233	22 mm (53%)	20 mm (22%), 21 mm (15%)
44 to 45 mm	133	22 mm (69%)	20 mm (8%), 23 mm (5%)
46 to 47 mm	50	22 mm (46%)	24 mm (14%), 20 mm, 23 mm and 28 mm (8% each)
48 mm and up	92	26 mm (49%)	24 mm (13%), 22 mm (10%)

Both the shape and the case size come from the listing, and a case listed with a decimal, such as 40.5 mm, sits in the row of its whole number. Our catalog doesn't record band widths under 12 mm, so the narrowest women's bands are missing from the smallest rows. If you're choosing the watch itself, our case size pages sort watches from mini to XL.

If you want one rule to remember, it's half the case size. On two in three round watches (839 of 1,267), the band is within 1 mm of half the case diameter, which is why a 40 mm watch so often takes a 20 mm band. Still, between 38 and 43 mm the most common width covers only about half the watches, and most of the rest sit a millimeter or two away.

The chart doesn't work for square, rectangular, oval or tonneau cases. Among the 233 non-round watches we counted, even the most common width, 20 mm, covers fewer than one in five (43 watches), so with a case like that, I'd measure before buying anything.

What size band fits a 38, 40 or 42 mm watch?

Those three are the case sizes we counted most often. At 40 mm the answer is usually 20 mm (102 of 165 watches), with 22 and 21 mm about one in ten each. At 38 mm, 20 mm still leads, but one watch in five takes 18 mm. At 42 mm the balance tips to 22 mm, though more than a quarter of those watches still take 20 mm.

And 41 mm sits right on the line: of the 58 round watches listed at 41 mm, 22 take 20 mm, 13 take 21 mm and 11 take 22 mm, so measure rather than guess.

If your 40 or 42 mm watch is an Apple Watch, none of this applies. Its bands slide into Apple's own slots and are sold by case size, not lug width. Smartwatches whose listing gives a band width, mostly Garmin and Amazfit, are in our count.

Here's what the listings say for some well-known watches:

Watch	Case (per listing)	Band width (per listing)
Timex Easy Reader (women's)	25 mm	12 mm
Anne Klein AK/2159	31 mm	12 mm
Nine West NW/2099	36 mm	14 mm
Timex Expedition Scout 36	36 mm	18 mm
Timex Weekender	38 mm	20 mm
Hamilton Khaki Field Mechanical	38 mm	20 mm
Invicta Pro Diver 40 mm	40 mm	20 mm
Orient Bambino Version 2	40.5 mm	21 mm
Longines HydroConquest	41 mm	21 mm
Orient Kamasu	41.8 mm	22 mm
Hamilton Khaki Field Automatic	42 mm	22 mm
Victorinox Dive Pro	43 mm	21 mm
Invicta Pro Diver 48 mm	48 mm	26 mm

A model name doesn't settle it either. The Timex Expedition Scout takes 18 mm at 36 mm but 20 mm in its 40 mm version. The Invicta Pro Diver name covers cases from 24 to 50 mm in our count, so its bands run from 12 to 26 mm: a 40 mm Invicta Pro Diver almost always takes 20 mm, the 42 to 47 mm ones 22 mm, and most from 48 mm up 26 mm. Our Invicta Pro Diver buying guide also tells you to start with size.

Are all watch bands the same size?

No, and odd sizes aren't rare. Every whole width from 12 to 30 mm turns up in our count, and 238 of the 1,588 watches (15%) take an odd one once decimals are rounded, most often 21 mm (110 watches). For some brands 21 mm is simply the house size: 20 of the 21 Victorinox Swiss Army watches we counted take 21 mm, and so do 16 of the 30 from Longines. The Orient Bambino Version 2 (40.5 mm case) and the Longines HydroConquest (41 mm) both take a 21 mm band too.

So what if you put a 20 or 22 mm band on a 21 mm watch? The 22 mm band won't fit. The 20 mm one goes on but leaves half a millimeter on each side and can shift. A one-piece NATO strap, which threads under the watch, can live with a 1 mm difference; for a two-piece leather or rubber band, look for the odd size.

What is the standard watch band size for men and women?

Watches	Counted	Most common	Next
Men's	832	22 mm (36%)	20 mm (29%), 26 mm (7%), 18 mm (7%)
Women's	422	14 mm (22%)	12 mm (20%), 18 mm (18%), 16 mm (18%)
Unisex	191	20 mm (42%)	18 mm (14%), 22 mm (14%), 21 mm (12%)

For men, if there's a standard, it's 20 or 22 mm: 540 of the 832 men's watches take one of the two (65%). Our case size study of 932 men's watches across Amazon US, UK and Germany found the same order, 22 mm first and 20 mm second; the counts differ because here we include only watches in stock on Amazon US whose own listing gives the width. Our men's watches page lists all the ones we track.

Women's watches have no single standard. Nearly nine in ten of the ones we counted take a band between 12 and 18 mm, and none of the four even sizes in that range stands out. They can also run narrower at the same case size: at 38 to 39 mm, seven in ten men's watches take 20 mm, while women's watches of that size most often take 18 mm. Here is the watch band size chart for women's watches alone, by case size:

Case size	Women's round watches	Most common band width	Next
Under 26 mm	27	12 mm (78%)	16 mm (11%)
26 to 29 mm	38	12 mm (39%)	14 mm (29%)
30 to 33 mm	75	14 mm (40%)	16 mm (29%)
34 to 35 mm	29	16 mm (34%)	12 mm (31%)
36 to 37 mm	70	18 mm (54%)	16 mm (19%)
38 to 39 mm	48	18 mm (35%)	20 mm (17%)
40 mm and up	23	20 mm (48%)	18 mm and 22 mm (13% each)

Some rows are small, and bands under 12 mm aren't in these numbers. To browse the watches, see our women's watches page.

What band size do Timex, Casio, Invicta and other brands use?

Brands with at least 25 watches in our count:

Brand	Watches counted	Most common	Next
Invicta	270	22 mm (31%)	26 mm (20%)
Timex	164	20 mm (45%)	18 mm (16%)
Citizen	154	22 mm (44%)	20 mm (12%)
Casio	110	22 mm (22%)	20 mm (19%)
Anne Klein	92	14 mm (35%)	12 mm (34%)
Rado	75	20 mm (47%)	18 mm (19%)
Hamilton	72	20 mm (64%)	22 mm (26%)
Guess	69	22 mm (23%)	24 mm (17%)
Bulova	60	22 mm (32%)	18 mm (18%)
Junghans	59	20 mm (56%)	22 mm (14%)
Orient	58	22 mm (43%)	20 mm (38%)
Nine West	53	16 mm (34%)	14 mm (32%)
Coach	30	18 mm (43%)	12 mm and 19 mm (10% each)
Longines	30	21 mm (53%)	15 mm and 22 mm (10% each)
Oupinke	28	20 mm (57%)	16 mm (18%)

A brand tells you less than the case size, with a few exceptions. Hamilton is the most consistent: 46 of its 72 watches take 20 mm, and our Khaki Field vs Khaki Aviation comparison lists the lug widths of both lines. Invicta has two peaks: 85 Invicta watches take 22 mm and 55 take 26 mm, almost all of those on cases of 48 mm or more. Casio is the hardest to guess, since even its most common width, 22 mm, covers only about one watch in five, so go by the model's own listing.

Timex sits in between. Its most common width is 20 mm, and the Timex Weekender takes it on 11 of its 14 listings, while the Timex Expedition line is split, with 20 mm on about half its listings and 18 or 22 mm on most of the rest. Orient splits between 22 and 20 mm, and our Mako, Kamasu and Ray comparison lists the lug widths of those divers. Anne Klein and Nine West, whose watches in our count are almost all women's, sit mostly at 12 to 16 mm.

How do I measure my watch band or strap size?

Measure the gap between the inner edges of the two lugs in millimeters. A ruler is enough if you use its metric edge: 20 and 21 mm differ by about 1/25 of an inch, too little to see on an inch scale. If a band is fitted, you can measure its end where it meets the case, or the spring bar that holds it, which is as long as the lug width. Band listings often give two widths, such as 20/16 mm: the first is the end that meets the case and has to match your lug width, the second is the buckle end.

The listing is a good start, but it can be wrong. Four listings of the Casio F-91W family in our catalog give four different band widths: 18, 19.25, 20 and 21 mm. We also set aside 30 listings whose band width was more than three quarters of the case size; in 16 of them the two figures were identical, which points to a mix-up. If the watch is on your wrist, trust the ruler over the listing.

What length band do I need for a 7 or 8 inch wrist?

Length is where your wrist comes in. Crown & Buckle, a US strap seller, lists its regular (standard) length two-piece straps (120/75 mm, the lengths of the two pieces) for wrists of about 6.5 to 7.5 inches, so a 7 inch wrist sits in the middle. The seller measured those ranges on a 40 mm watch with a 47 mm lug-to-lug and notes that the size of the watch, the shape of its lugs, the strap's thickness and how tight you wear it all change the fit.

For an 8 inch wrist, a regular two-piece strap is likely to come up short, so look for one sold in a long length, or go for a one-piece NATO: the same seller lists its 280 mm NATO straps for wrists of about 5.75 to 9 inches. If the band that's too long is a metal bracelet, you don't need a new one: a bracelet is sized by taking out links.

To measure your wrist size, wrap a strip of paper around it where the watch sits, mark where the end meets the strip and lay it on a ruler. Our guide to sizing a watch explains what that number means for the case, and our watch size calculator turns it into a case size range.

How we checked

The numbers come from the Bravery Watch catalog on October 22, 2026. Of the 2,097 watches in stock on Amazon US with a price updated in the past seven days, 1,723 had a band width. We counted only the 1,621 widths taken from the "Band Width" line of the listing's spec table; for 102 watches the width was our own estimate rather than the listing's, so we left them out. We also dropped the 30 listings whose band was wider than three quarters of the case, and 3 fitness trackers, such as the Xiaomi Smart Band 10, whose strap has no lugs. That leaves 1,588 watches, including 44 smartwatches, mostly Garmin and Amazfit; Apple Watch listings don't give a band width. The 75 widths given with a decimal were rounded to the nearest millimeter, exact halves to the even number. Our catalog keeps band widths from 12 to 30 mm only. The case size chart counts the 1,267 round watches whose listing gives the shape and the case size. Men's, women's and unisex come from the listing's department or its title; the 143 watches whose department isn't stated in the listing's spec table or title, or that are kids' watches, are left out of that table. These are the Amazon listings in our catalog, not every model a brand makes.