Waterproofing and wearables: We explain IP and ATM ratings

Water-resistance standards have rapidly improved in smartwatches and other wearables over the last few years. 

What started out as basic splash protection has now, in most watches, developed into full-fledged ingress protection suitable for swimmers. In some cases, even divers are catered for.

If you're new to smartwatches, though, all the jargon surrounding specs, disclaimers and water ratings can be a little daunting. 

And if you plan on dunking in the water consistently - or perhaps even just showering with your smartwatch on - there are plenty of questions you might need answering. That's where this guide comes in.

Below, you'll find all the explanations you need behind the water resistance claims assigned to smartwatches. Let's dive in.

> Best waterproof smartwatches for swimming

TL;DR: How to tell if your wearable is swim-proof

If you're looking for a swim-proof wearable, aim for a device with 5ATM and IPX8 ratings (or higher). Having at least both these marks will mean your watch has both ingress protection for continuous immersion in water, as well as the ability to deal with a good level of water pressure.

How to navigate water resistance claims

As you'll know if you've ever tried to decipher a product's actual ability to deal with water, there's rarely a straightforward answer. 

The IP and ATM ratings we'll talk through below do standardize the process and give you something to look out for, but you'll still need to put these two together if you want to figure out if a watch is truly swim-proof, dive-ready or will probably brick if you take a shower with it. 

This is all well and good in theory, obviously, but manufacturers often don't list both ratings.

It's common to see an ATM rating (which only relates to conditions equivalent to different water pressures) but not an IP rating (which looks at how protected a device's enclosure is from dust and liquids), and the reverse is also some brands' preference. 

This leaves things quite vague, so do your best to dig this information out if it's not immediately clear, and, obviously, try and protect your device from water if you're not entirely sure. 

Water-resistant vs. Waterproof

The industry is also amock with different terms for defining water protection.

Splash-resistant, swim-proof, moisture-resistant, sweat-proof, water-resistant, and waterproof are the main variations that you'll likely read in the descriptions of products. 

Since no wearable is technically waterproof, however, the question really is about the extent of a device's resistance. And, as we've mentioned above, you'll need to do this by finding a product's IP and ATM water ratings (explained below).

The same is true if you encounter any other terms used to describe a device's ability to handle water. Some splashes are bigger than others, after all, and both sweat and moisture levels are pretty subjective.

In order to present this information easily, manufacturers will often list these water ratings in the specs sheet and dress up marketing material with caveated lines like "waterproof up to 50 meters". 

So, look for the ratings, match them up, and remember that true waterproofing doesn't technically exist in watches.

IP ratings explained

An Ingress Protection rating is an official indicator of how well your device is protected against dust and water. 

While not relating to water, we should mention that the first numeral you see after 'IP' relates to protection against solid objects, with '0' being no protection and '6' given to devices with no ingress of dust. 

Generally speaking, most new devices you come across will offer a '6' on this rating.

The second number is the important one for those concerned about water protection. This relates to the rating given to the enclosure's protection against liquids, using a scale of 0-9. 

You'll often see smartwatches and wearables on the upper limits of these, but, for the sake of completeness, here are some rough descriptions for each IP water rating:

• IPX0 = No water protection
• IPX1 = Protected against vertically falling water drops
• IPX2 = Protected against vertically falling water drops when the enclosure is tilted up 15 degrees
• IPX3 = Protected against spraying water
• IPX4 = Protected against splashing water
• IPX5 = Protected against water jets
• IPX6 = Protected against powerful water jets - as well as heavy rain and outdoor sea conditions
• IPX7 = Protected against the effect of temporary immersion in water up to 1m for up to 30 minutes
• IPX8 = Protected against the effects of continuous immersion in water better, as specified by the manufacturer
• IPX9 = Protected against high-pressure and temperature water jets

Example: The Samsung Galaxy Watch 5 and Galaxy Watch 5 Pro both feature an IP68 rating, meaning they are protected completely against dust while also offering protection against continuous immersion in water.

ATM ratings explained

While the IP ratings covered above relate to water resistance, ATM ratings instead show how deep a device can go and how much water pressure it can theoretically withstand.

ATM is simply an abbreviation for 'Atmosphere', and these ratings are handed out by the Internation Organization for Standardization (ISO). 

This is particularly important for those who plan to swim or dive using their wearable - as, hypothetically, a device may offer a certain level of water protection but still not survive certain levels of water pressure.

Remember, as well, that this rating certifies equivalent pressures to that of a certain ATM, and variables like time in the water and potential ingress protection damage can affect a device's ability to withstand water pressure.

These ratings aren't a to-the-meter guarantee, basically, and it's best to err on the side of caution when testing depths with them (unless they're certified for diving, which we'll explain below).

• 1ATM = Withstands pressures equivalent to 10m / 33ft
• 3ATM = Withstands pressures equivalent to 30m / 98ft
• 5ATM = Withstands pressures equivalent to 50m / 164ft
• 10ATM = Withstands pressures equivalent to 100m / 328ft
• 20ATM = Withstands pressures equivalent to 200m / 656ft

But a wearable's ability to withstand water pressure at a certain depth looks very different in real-world situations, as we'll go on to explain.

Swim-proof smartwatches: What to look for

You've seen a smartwatch or wearable you like with a 3ATM rating, which means it should be able to join you in watery depths of 30m, right? Well, not necessarily. 

Firstly, remember that these are simply lab estimates of the kind of water pressure the device can deal with, and, secondly, the correct ATM rating should be paired up with an equally appropriate IP rating.

Essentially, there's no real point in owning a device capable of 3ATM if, for example, it's only received an IPX4 rating.

Thankfully, it's often a bit easier than this to figure out if something is swim-proof, and you're looking for IPX8 protection and a 5ATM rating.

In theory, such a combination should mean a device should be safe for swimming or snorkeling, though different manufacturers may sometimes also state variables relating to time or specific depths that you'll need to watch out for. 

If you only see an ATM rating - as we mentioned earlier, there's now a trend of brands listing just one - this is likely because it's assumed one rating is enough to figure out whether it's swim-proof. 

The Garmin Fenix 7 listing, for example, shows off a 10ATM rating but doesn't specifically highlight any dust or water ingress protection.

In our experience, high ATM ratings have always equated to a device being swim-proof, but it's worth remembering that this rating doesn't automatically guarantee it.

Smartwatch diving: What to look for

Wearables and smartwatches with 10ATM ratings are becoming more commonplace - but this doesn't necessarily mean they're ready for dives down to exactly 100m.

In order to be dive-ready, they'll also need an EN13319 certification (like the Apple Watch Ultra), and you'll also have to check each manufacturer's fine print on how deep in the water an individual device is actually designed to go down to.

Again, like with trying to hunt down information regarding swimming support, it's likely that you'll often see only the ATM rating listed in the specs of potential diving-compatible smartwatches. 

It's often fair to assume it has an IPX8 rating if the manufacturer is touting it as ready for dives, but try and double-check to make sure.

Which smartwatches are the most water-resistant?

We have a complete buyer's guide to the best water-resistant smartwatches, but, for those looking for an idea of what's out there, below are some examples of the devices that offer the top water ratings and certifications. 

As we've alluded to up top, most modern smartwatches now offer IPX8 and 5ATM, but below are the options that currently go that step further. 

• Apple Watch Ultra - 10ATM, EN13319 certified
• Apple Watch Series 8 - 10ATM
• Garmin Fenix 7 / Garmin Epix 2 - 10ATM
• Garmin Descent Mk 2 - 10ATM, EN13319 certified
• Garmin Descent GI - 10ATM, EN13319 certified
• Huawei Watch GT 3 Pro - 10ATM, EN13319 certified