Watch Case Size Calipers

How To Measure A Watch Case Size Easily

In Watch Guides by TSW Staff

So you’re looking for a watch and you wonder: How do I measure a watch case size? What even is the watch case size and what does it mean for my wrist? Your quest is over! Knowing exactly how to measure your watch case is important if you’re serious about getting the right watch for you.

To measure a watch case size, place calipers from one side to the opposite side of the case, just above or below the crown, where the case diameter is the smallest. The easiest way is to measure the case from the 4 o’clock to 10 o’clock position or from the 2 o’clock to 8 o’clock position.

Most of the time, the case is the smallest at the 3 to 9 o’clock position. But most watches have the crown at the 3 o’clock position; this is why you should measure it just above or just below it. The lug to lug distance is also a very important factor. Last but not least, measure how far apart the tip of the hour markers are. This makes a big difference. Read on for the full guide!

How to measure a watch case size

It’s pretty easy.

Measure the case from one end to the other of the central portion of the watch, without the crown or any pusher. On a simple watch with just a single crown at 3 o’clock (like most watches), it’s easiest to measure the case from 2 o’clock to 8 o’clock.

If your watch case has a pillow or square shape, then get the smallest measurement you can possibly get.

We measure watch sizes (the case, but also the band width or the thickness, for example) in millimeters. It’s easier to use digital calipers. If you don’t have any, you can also use analog calipers or even a simple transparent ruler.

Using digital calipers to measure a watch case size.

In that case, make sure to align the ruler as best as you can with the edge of the watch case. Also, read the size right from above the edge of the case – and not at an angle. This is to avoid parallax and a wrong reading. Pay attention not to scratch the crystal when using a ruler.

A watch case size is best measured from 2 o’clock to 10 o’clock.

Of course, you don’t have to measure the watch case size yourself: most manufacturers and online sellers will give you this information.

Beware though! Quite a few times, I read some wrong information on big marketplaces like Amazon (and even some manufacturers’ websites!). So before taking any watch size for granted, check the information twice.

The best way to do so is to go to the brand’s website and look a the specs. Then cross-check on a dedicated site like WatchUSeek forums. But if you’re on a dedicated website, and the information comes from a watch enthusiast reviewing a watch, you can rest assured that he did his homework and that the watch case size he gives you is the right one.

How to measure the lug to lug distance of a watch?

Imagine a naked watch head, with no bracelet or band. The lug to lug distance is measured from the tip of the lug on one side of the watch to the tip of the lug on the other side of the watch.

Beware not to measure the distance between two lugs on the same side of the watch: this is the lug width. That can be a bit confusing so here is the image worth a thousand words :

How to measure the lug to lug distance and the lug width of a watch.

Of course, you don’t have to remove the bracelet or band of the watch to measure the lug to lug distance.

You’ll see that very few manufacturers or shops give you the lug to lug distance of a watch. And it’s hard to find that information on the Internet. That’s why you’ll have to measure it yourself or find it on dedicated forums.

Hint: if you’re looking for this on Google, try to search for your watch model and “L2L”, you may find that information on dedicated forums quicker.

Now here is the important part: you want the lug to lug distance of a watch to be smaller than the width of your wrist. Not the size (or circumference) of your wrist, its width. Doing so, you make sure that the watch head will not

Why do some watches look smaller than they are?

Maybe you heard some watch enthusiast say: “this 40mm watch wears like a 38mm watch”. What does that mean and how is it possible?

When you’re used to wearing watches all day every day, you begin to develop a deep sense of how a watch fits on your wrist. So you know how a 38mm watch looks on your wrist, and you can spot the difference with how a 40mm watch looks.

Some watches wear (or look) smaller than they actually are. Conversely, some watches wear bigger than they should. Why is that?

This comes down to several factors, but the 2 most important ones are the watch bezel and the hour markers circle.

A bezel changes how big a watch looks

If two watches have the exact same case size, but one has a bezel and the other one doesn’t, the watch with the bezel will appear smaller than it actually is. Even more surprising, a watch can have a bigger case than another one and still manage to look smaller, because of the presence of a bezel.

The Orient Ray 2 (on the left), while bigger, looks smaller than the Seiko SRPB41.

As you can see on this picture, the Orient Ray 2 looks smaller than the Seiko Cocktail Time Blue Moon. Yet the Orient has a 1 mm bigger case than the Seiko! The one on the left is a 41.5mm watch while the one on the right is 40.5mm watch.

And the reason is quite simple: for any given watch case size, the bigger the bezel, the smaller dial. And because the dial of a watch is the cart that we are most drawn to look at, it makes the watch actually look smaller.

Which leads me to the second factor that influences the relative (or subjective) size of a watch.

The hour marker circle changes how big a watch looks (too)

The hour markers circle size is measured from one tip of an hour marker on the dial to the tip of the opposite hour marker. The hour marker circle is not a physical dimension of the watch. But it’s one that is very prominent when you look at a watch.

It’s actually not so easy to measure the hour markers circle precisely because it lives inside the case. But you don’t have to be overly precise: gently apply a ruler on the crystal of your watch and get that measurement as best as you can.

How to measure the hour markers circle.

Now, if your hour markers are not made of only one line, one number or one shape, what should you measure? Pick the most visible feature of the hour marker and measure for one tip to the tip of the opposite hour marker feature.

Thin line and big number: measure the numbers. Small number and thick line: measure the lines. You get the idea.

So for a given watch case size and a bezel size, the smaller the hour markers circle, the smaller the watch will look.

Wrapping up

It’s important to check all the important size of a watch: its case width, lug to lug distance, bezel width, and hour marker circle size. By doing so, you make sure to get the proper watch for your wrist.

Not sure what watch size you should get for your wrist? Check my extensive watch size guide. Or maybe you need a men’s watch? Check my favorite men’s watches for small wrists. They look great on larger wrists, too!

About the Author

TSW Staff

The Slender staff writers are watch enthusiasts and experts who love writing about watches and helping people find their next favorite timepiece.