Lug width
How to measure your watch's lug width
The number that decides which straps will ever fit your watch. It takes a minute to measure and it constrains every strap you buy for as long as you own the watch.
By Sawyer V. · Published
The short answer
Lug width is the gap between the two lugs, measured in millimeters, and it is where the strap sits. Measure it with a ruler across the inside of the lugs, or read it from your watch's product page. 20mm and 22mm are the common sizes; 19, 21 and 23mm are the awkward ones that narrow every future strap purchase.
Every strap sold online is listed by width in millimeters, and buying the wrong one is the single most common mistake people make when they try to change a strap for the first time. A 20mm strap will not go into an 18mm gap, and a 22mm one will rattle in it.
The number you need is the lug width: the distance between the inside faces of the two lugs, where the spring bar sits. It has nothing to do with the diameter of the watch, and nothing to do with the length of the strap. This page covers how to get it in about a minute, and why some watches make the rest of your life harder than others.
On prices: we publish no figure we have not verified today. Where a live price is shown it came from the price layer this morning; otherwise the button reads "Check price on Amazon".
How we picked
We have not worn these watches. What follows is what we checked instead, on documents you can open yourself — the same criteria, in the same order, on every roundup on this site. The full method is on the methodology page.
01What it is
The distance between the inner faces of the two lugs, in millimeters. It is the width of strap the watch takes.
02How to measure
A ruler across the gap, or calipers if you have them. Always measure the gap, not the strap you already own.
03Even or odd
18, 20 and 22mm are made by everyone forever. 19, 21 and 23mm are stocked by a handful of makers.
04Not the same as strap length
Length is about your wrist. Width is about the watch, and only width decides whether a strap physically fits.
The one-minute method
Take the strap off, or push it aside, and lay a millimeter ruler across the gap between the lugs. Measure from the inside face of one lug to the inside face of the other. That figure, rounded to the nearest millimeter, is your lug width. Almost every watch is an even or odd whole number between 16 and 24mm.
Two things to avoid. Do not measure the strap you already have — straps taper, and the end that meets your wrist is narrower than the end at the lugs. And do not measure the outside of the case, which includes the lugs themselves and will read several millimeters too wide.
If you would rather not measure at all, the manufacturer publishes it. Every watch reviewed on this site prints the lug width in its specification table, taken from the maker's own page — and where a maker does not publish it, the table says so rather than guessing.
Common sizes, and what fits what
| Lug width | Typical watches | How easy are straps? |
|---|---|---|
| 16-18mm | Small dress and vintage-sized watches, some field watches | Easy, though the choice thins below 18mm |
| 19mm | Tissot Le Locle and a handful of dress watches | Hard — only a few ranges cover it |
| 20mm | The most common size on this site: field watches, divers, dress watches | Easiest of all |
| 21mm | Several Seiko, Tissot, Orient and Citizen references | Hard — a handful of ranges only |
| 22mm | Larger divers and sports watches | Easy |
| 23mm | Citizen World Chronograph and a few others | Hardest of the lot |
| 24mm | Large sports watches | Easy enough, choice narrows |
Why odd widths are a real cost
An even lug width means straps are a commodity: every maker, every material, every price, forever. An odd one — 19, 21 or 23mm — means a much smaller pool of ranges, and it stays that way for as long as you own the watch.
That is why lug width is one of the six specifications in the Keep Score. It is not about whether the watch is good; it is about whether the next twenty strap purchases are easy or annoying. On this site, seven watches take 21mm and the Tissot Le Locle takes 19mm.
If you already own one of them, the options do exist. Barton's Alligator Grain leather line is made in 16 to 24mm including all three odd sizes, and its Elite Silicone covers the same range — both are on the leather strap roundup and the quick-release strap page, which lists every watch on this site with an awkward width.
Watches that take no strap at all
A few watches have integrated bracelets, where the bracelet is shaped into the case rather than attached by conventional spring bars. The Tissot PRX takes a 12mm interlug fitting, the PRX 35mm an 11mm one, and the Citizen Tsuyosa is built the same way.
On these, no standard strap fits at any width. That is a design choice rather than a defect, but it means the bracelet you buy is the bracelet you keep — worth knowing before rather than after.
Lug width against lug-to-lug
These two get confused constantly and they measure different things. Lug width is across the gap, and decides which straps fit. Lug-to-lug is the length of the whole watch from the tip of one lug to the tip of the other, and it decides whether the watch fits your wrist.
Both matter, but for different purchases. If you are choosing a watch, lug-to-lug is the number to check — see best watches for small wrists. If you are choosing a strap for a watch you already own, lug width is the only one that counts.
Quick-release bars, while you are in there
If you expect to change straps more than once, buy straps with integrated quick-release bars. They have a small lever on the spring bar that retracts it, so the strap comes out in a second with no tool and no chance of scratching the lugs — which is how most people mark a case.
They fit any watch with conventional lugs, in the correct width. The strap guide covers materials, and the quick-release page covers the hardware.
Questions people actually ask
How do I measure my watch's lug width?
Lay a millimeter ruler across the gap between the two lugs and measure from the inside face of one to the inside face of the other. Round to the nearest millimeter. Do not measure the strap, which tapers.
What is the most common watch lug width?
20mm, followed by 22mm. Both are made by every strap manufacturer in every material, which is why this site scores even widths above odd ones.
Is lug width the same as strap width?
Yes at the lug end — a 20mm lug width takes a 20mm strap. The strap usually tapers to a narrower buckle end, which is why measuring an old strap can mislead you.
What if my watch is 19mm or 21mm?
Straps exist but the choice is much smaller. Barton's Alligator Grain leather and Elite Silicone lines are both made in 19, 21 and 23mm, which is the widest odd-size coverage we found.
Can I put a 20mm strap on an 18mm watch?
No. It will not fit between the lugs. Going the other way, an 18mm strap in a 20mm gap will sit loose and move around, which looks wrong and wears the strap unevenly.
Sources
Every specification and figure on this page came from one of these documents. Where a manufacturer does not publish something, the page says so rather than filling the gap.
Read next
Watch straps
Lug widths, materials and quick release — and why an integrated bracelet is a decision.
Best quick release watch straps
Tool-free straps compared, and the odd lug widths that make them hard to find.
Best leather watch straps
Five leather straps compared on tannery, lining, buckle grade and width range.
Best watches for small wrists
Eight watches under 48mm lug-to-lug, with the measurement that actually decides fit.