How To Measure A Watch Case Size

Are you wondering how to measure a watch case for size? We cover all the basics to have you measuring like a pro in no time!

So you’re looking for a watch and wonder: How do I measure a watch case size? What 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 watch diameter or 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 to 10 o’clock position or from the 2 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, so you should measure it just above or below it. The lug-to-lug distance is also a very important factor. Last but not least, measure how far apart the tips of the hour markers are. This makes a big difference. Read on for the full guide!

What Is a Watch Case?

The watch case is essentially a durable shell that protects and holds the watch’s bezel, dial, and movement. It comes in a variety of materials. Usually, it’s made of stainless steel, but you can also find a case in gold and other precious metals, titanium, and ceramic. Brands construct watches—particularly fast fashion or sports watches—out of various plastics. This helps keep costs down, but they aren’t as long-lasting as metal. 

You can find a variety of watch case shapes stylistically. Round cases are the most standard and classic shape, followed by square and rectangular watch shapes. Small oval watches have ebbed and flowed in popularity for women over time, but you can also find interesting shapes. Think Avant-garde, asymmetrical, or even the headscarf or Cheich case shape of the ultra-rare Cartier Cheich.

Last, many would agree that the watch case is more important for functionality than style. After all, without the case, you really wouldn’t have a watch. Style aside, the case’s purpose is to protect your watch’s inner workings. It protects your movement from dust, dirt, moisture and water damage. Plus, it absorbs most of the impact of daily wear. 

What Is Case Size on a Watch?

Simply put, the watch case size is the diameter of the watch case. More times than not, the watch case measurement is measured in milimeters. When it comes to size, you need to consider the shape of your watch. In round watches, you take the measurement across the face of the watch. For square shaped watches, you take the watch measurement across the shortest side of the case. Still not sure, don’t worry. We’ll divulge specifics about measuring shortly. 

Determining case size is crucial to picking a watch that is best for your wrist. It helps with comfort ensuring you watch fits your wrist correctly. The right case size also is aesthetically pleasing offering the correct proportion to your wrist. 

How To Measure a Watch Case Size

Measuring watch case size is 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, get the smallest measurement possible.

We measure watch face sizes (the case, but also the band width or thickness, for example) in millimeters. It’s easier to use digital calipers, but you can also use analog calipers.

Of course, you don’t have to measure the watch case size yourself: most manufacturers and online sellers will provide a watch case size guide. 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 at the specs. Then, cross-check on a dedicated site like watch forums. If you’re on a dedicated website and the information comes from a watch enthusiast reviewing a watch, you can rest assured. Enthusiasts do their homework and that the watch case size they give you is the right one.

How to Measure Watch Case Size With a Ruler

To measure watch case size with a ruler correctly, you’ll want a ruler that gives you the option to measure in milimeters. Sure, you can use inches and convert to milimeters but a milimeters ruler gives you the most precise results. Especially, if you’re using a ruler or tape measurer to measure. 

As with measuring case size with calipers, you’ll want to measure a round watch at the 2 and 8 O’Clock markers. 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.

How To Measure the Lug-to-Lug Distance of a Watch?

Imagine a naked watchhead without a 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 on the other side.

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 check out the image above to help guide you.

Of course, you don’t have to remove the watch’s bracelet or band 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 quicker on dedicated forums.

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. 

Measuring Thickness

Again, using calipers to measure thickness offers the most accurate results. To use calipers you’ll place one of the caliper jaws on the watch crystal towards the center of the watch. Take care to not scratch your crystal! Then, place the other jaw central to the back of the case. Closing the caliper will give you the thickness measurement of your watch. 

You can also do this with a ruler. Lay your watch flat on a counter and then measure the side of your watch from the bottom of the case to the top with a ruler. This measurement may slightly be off as this measurement doesn’t take the curvature of your watch crystal into account.

When using a ruler you want to try to get a measurement as close to the bottom of the side of the watch case as possible. In the image above, the lugs raise the case a little bit so it doesn’t sit flush on the counter. In this case you’ll want to adjust the ruler with the bottom of the side of the case. Or, take note of the measurement between the counter and the bottom of the case. Then, subtract that from your overall measurement.

Why Do Some Watches Look Smaller Than They Are?

Maybe you have 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 two 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 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.

As you can see in the above 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 a 40.5mm watch. The reason is quite simple: for any given watch case size, the bigger the bezel, the smaller the dial. And because the watch’s dial is the part that we are most drawn to look at, it makes the watch look smaller.

This leads me to the second factor that influences a watch’s relative (or subjective) size.

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 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.

Now, if your hour markers are not 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.

FAQ

You may have more questions about watch case size and that’s perfectly okay. This FAQ section addresses some of the common queries regarding watch case sizing. 

What Does Case Size Mean on a Watch?

On a watch, the case size is the watch diameter or the measurement of the watch across its face. 

How Big Is a 47MM Watch?

A 47MM watch case equates to one that is about 1.85”. This is considerably large men’s watch case size and will look prominent on most wrists. Particularly so if you have a slender wrist. If you have thin wrists, 36MM to 38MM watches are ideal, 40MM at absolute most. 

What Does 41MM Mean on a Watch?

If 41MM is engraved on your watch case or you see it in watch details on a website it is often referring to the case size. 41MM is just over an inch and a half. 

Wrapping Up Watch Case Size

It’s important to check all the important sizes of a watch: the watch case width, the lug-to-lug distance, the bezel width, and the hour marker circle size. By doing so, you can ensure that you 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!

Do you have any handy tips on measuring watch case size? Drop them in the comments below and let us know!