People are often concerned about the size of a watch and rightfully so. Not every watch will fit well. In case of vintage watches, specific sizes are more desirable than others.
Still, often the information provided isn’t complete, wrong, or – in the case of some listings – false.
So, what’s the deal with watch dimensions?
The lug width and lug-to-lug
The lug width is the distance between lugs along the 3-9 o’clock line (horizontal). In other words, this measurement determines the width of a strap/bracelet.
Of course, there are exceptions. Watches with integrated bracelets, for example. They don’t have lugs as such, so…
The Lug-to-lug, or the length of the case, is the distance from the tip of one lug to the matching one on the other side of the case, along the vertical line (12 to 6).
This is, in fact, the most critical measurement. It determines how the case spans across the wrist.
That said, we often mean the circumference when we’re talking about the wrist size but it’s not the circumference that matters.
People often ask, “will this or that watch fit on my 6.5-inch wrist?” Take a caliper, check the width of your wrist, and look up the lug-to-lug size of the watch you’re considering. Then you’ll know if the lugs will stick out beyond your wrist or not. It’s not the standard way to measure your wrist, but it’s the most practical one.
I’ve often seen people confuse the lug width with the lug-to-lug. This is notorious with microbrands at forums.
A watch has a diameter of 42mm, and potential buyers ask about the lug-to-lug size. The brand rep answers, “The lug to lug is 20mm.” Nope, it’s not.
Diameter without the crown
This measurement is mostly provided by manufacturers and sellers. Funnily, it’s not relevant regarding the fit.
The diameter is usually measured from 9 to 3 o’clock, or from 12 to 6. In the case of the Omega Speedmaster, it’s presumably measured from 8 to 2 o’clock, so that the crown and pusher guards are included.
In the case of vintage watches, “oversized” cases seem to be most valued. Essentially, this means a case with a diameter that’s larger than the average size at the time the watch was made. To call 35-36mm an oversize is stretching it. However, 37-38mm do fit into that category.
Unfortunately, in a lot of listings, the diameter provided is entirely false. But, more on that later.
Anyway, there’s a simple way of estimating the diameter yourself, if you know the lug width. If you do, use it for reference. Take a line of that length and put it up against the watch, from the edge of the case at 9 o’clock to the center. Then, you’ll be able to estimate the diameter roughly. That way, you’ll be able to check if the diameter in the listing is correct.
Carefully check the photos in the listing. The width is often noted on the underside of the strap. This matters, because the diameter that the less honest sellers provide, often turns out to be the…
Diameter with the crown
It’s just the diameter, only plus the thickness of the crown. In other words, from 9 o’clock to the tip of the crown. Or from 3 o’clock, if you’re dealing with a watch with the crown at 9.
It’s perhaps the least useful, borderline useless measurement. Putting a chunky crown on a 34mm watch won’t make it a 37mm… or will it? According to some sellers, it does.
Many want to sell commonly sized watches as uncommon, oversized ones. So, they take the diameter…with the crown, and knowingly don’t bother to mention that in the listing.
Of course, including this measurement isn’t wrong, as long as the diameter without the crown is provided in the first place.
The thickness of a watch is measured from the highest point of the case back to the highest point of the crystal (if the crystal is domed).
People are often worried about the thickness. If it’s on the larger side, the obvious concern is that the watch will feel top-heavy on the wrist. And so it won’t stay in one place.
That’s often not the case. Thickness is relevant when combined with the center of gravity. A big watch with a dome in the center of the case back has most of its mass closer to the top. The smaller area of the case back in contact with the wrist causes an entirely different feeling than the thickness alone would suggest. Watches with the same thickness, but a different center of gravity will wear differently. Note: the watch with a more flat back will feel less top-heavy.
Also, keep in mind that the crystal weighs little. Perhaps a thick sapphire one does, but not a hesalite one. So, even if a watch is thick because of the high-dome hesalite crystal, this doesn’t mean that the center of gravity will be higher. Well, lower, concerning the thickness itself. But apparently, it won’t be any higher regarding what it feels like on the wrist.
Dimensions of rectangular and tonneau cases
With a tonneau case, the relevant dimensions are the lug-to-lug x width from 9 to 3 (without the crown).
A rectangular case has the same width throughout, so let’s call it width x lug-to-lug.
Sometimes, the length (vertical line) is given without the lugs, which is useless in determining the fit of the watch.
Do you have any more questions about watch dimensions? Let me know in the comments below.