3 ATM Water Resistant: Full In Depth Explanation

In this article, we are going to thoroughly go over what is meant by 3 ATM water resistant. You may have noticed that some watches will be rated by “ATM”. So, first things first, what does 3 ATM mean?

The simple answer is that 3 ATM water resistant means that a watch is water resistant to a depth of 30 meters. That’s the textbook answer, but as you will soon discover, the true reality of it is a bit more complicated.

There are a lot of misconceptions about what 3 ATM is and isn’t. Throughout this article, you will learn point by point most anything you need to know about 3 ATM water resistance. We will begin by explaining the abbreviation “ATM”.

What Is Meant By The “ATM” in 3 ATM?

So first off, the abbreviation “ATM’, actually stands for “atmospheres”. This is in reference to how much pressure the watch can withstand. Or more specifically, the amount of pressure that a watch can withstand below sea level.

This can be measured in meters or feet, but meters is the most common unit of measurement. The next common question concerning ATM number is how you would determine the meters of resistance relative to the ATM number.

How To Calculate The Number Of Meters Of Water Resistance From An ATM Number

All you need to do to find out how many meters an ATM number stands for, is to multiply the ATM number by 10. So in the case of 3 ATM, 3X10 is 30. So that is how we get 30 meters of water resistance from 3 ATM.

Now, you may be wondering why even call it ATM, instead of just using meters to begin with? Well, there is a special distinction when it comes to using the term “ATM”.

Why Call It “ATM” In The First Place?

We already learned that ATM stands for “atmospheres”, and also that it refers to the pressure a watch can withstand below sea level. So how does this work exactly?

Well, let’s start with 1ATM. This starting point, is the pressure of the earth’s atmosphere at sea level. The 1ATM would mean 10 meters of pressure. Now, for every 10 meters you go below sea level, you would add another “atmosphere”, or ATM.

Hence 2ATM would mean 10 meters below sea level, 3ATM would mean 20, and so forth. That is the technical definition of ATM. So wait, why then does a 3ATM rating on a watch mean 30 meters of water resistance? Shouldn’t it be 20?

I can only assume that watch manufacturers use these labels to simplify things for consumers. So they will be labeled at 3 ATM as 30 meters of resistance, 5ATM as 50 and so forth.

And yes if a watch has these ratings, they do mean that the watch can withstand the listed depth, rather than the technically correct ATM definition. But as you will see in a minute, these labels don’t mean what you might think in more ways than one!

Can A 3 ATM Water Resistant Watch Really Withstand A Depth Of 30 Meters?

Now that we know a little more about ATM, let’s say that we are dealing with a 3 ATM water resistant watch. Is it really made to be taken 30 meters underwater?

The answer is that theoretically, yes a 3 ATM water resistant watch could withstand the pressure of a depth of 30 meters. However, in all practicality, it probably can’t. So why is this?

It has to do with how a watch is rated for water resistance. Most watches are not rated based on the ability to withstand being taken underwater to their rated depth. Rather they are rated based on being sprayed with a stream of water that gives the equivalent of their rated water resistance.

Let’s stick with the 3ATM as an example. In this case a 3 ATM water resistant watch is rated based on its ability to withstand a stream of water being sprayed at it that is equal to 30 meters of pressure.

This is all well and good, but there is a difference between being sprayed with a force equal to 30 meters of pressure, and actually being taken 30 meters underwater.

With the water jet spray, the watch is only exposed to that type of pressure to a brief period. Furthermore, when you actually go 30 meters underwater, that pressure is continuous, and surrounding. So theoretically, a watch could withstand being taken 30 meters underwater.

However, it may not be able to, and if it can, it might not be able to do it for a prolonged period of time. So what kind of applications would actually apply to a 3 ATM water resistant watch?

What You Can And Can’t Do With 3 ATM Water Resistance.

In reality, a rated water resistance of 30 meters is not really much at all. Based on the way in which water resistance ratings are measured, 3 ATM water resistance basically amounts to splash resistant.

What this means is that you can probably wear it in the rain, and wash your hands with it on. If water or liquids spill on it, it should be fine. And it may be ok to shower with it, but I wouldn’t recommend that either.

What you can’t or shouldn’t do is wear it while bathing, swimming, or diving. There are no guarantees that a 3 ATM water resistant watch can withstand full submersion in water for any length of time.

For reference, here are some general guidelines concerning ATM resistances.

ATM Water Resistance General Applications

  • 3-5 ATM: Can withstand splashes of water, rain, and maybe even showering, but shouldn’t be fully submerged in water.
  • 10 ATM: Can handle swimming, snorkeling, and maybe even scuba diving.
  • 20 ATM: Can handle deep diving.
  • 30 ATM and up: Suitable for professional diving, or saturation diving.

Final Thoughts

To wrap things up, we now know that 3 ATM water resistant watches are pretty much just splash resistant watches. They are not really meant to be fully submerged to a depth of 30 meters for any period of time really.

Hopefully this clarifies things, so that when you are looking to buy a water resistant watch, you should now have a better understanding of what ATM means.

That concludes our look into 3 ATM water resistance. If you enjoyed this article, then feel free to check out some more of our Info articles to learn more interesting facts about watches. You can find those articles here

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3 thoughts on “3 ATM Water Resistant: Full In Depth Explanation”

  1. That’s at sea level. What happens above sea level, like in the mountains, 6,000+ feet? Or below sea level?

    • The watch starts running backwards, time reverses, and you travel through time into another unknown dimension.


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