Waterproof Running Watches: IPX and ATM Ratings Explained

Question:

I am looking to purchase a waterproof GPS running watch. I occasionally do triathlons and need a GPS watch with a waterproof rating to support swimming yet versatile enough to train for marathons and long runs. I see running watches that have various IPX and ATM ratings. What exactly do these mean, and how do I know which running and triathlon watches are best for running and swimming?

Answer:

First, thank you for the question. IPX and ATM are rating standards that describe how much water a watch can handle. I describe both standards below, but I also want to put them into perspective for what they actually mean for a runner or triathlete.

The short version for 2026: this used to be a real buying decision. It mostly is not anymore. Nearly every current GPS running watch is rated 5 ATM, which is swim-safe, and the tougher multisport models are 10 ATM. Of the 17 current watches in our Running Watch Finder, 13 are 5 ATM and 4 are 10 ATM. Not one of them would be a problem in the rain or the pool.

So the honest answer is that you should choose your watch on features, battery, and fit, and treat the water rating as a box that is already checked. The detail below is still worth understanding, especially if you are looking at an older or secondhand watch, where ratings varied a lot more.

Water-resistant versus waterproof running watches

Generally speaking, a water-resistant watch is fine for running and cycling. It will handle running in the rain without issue. You would not want to swim in it.

Water-resistant running watches are the ones rated IPX-6, IPX-7, or IPX-8. IPX-7 and IPX-8 watches are protected for short periods when accidentally immersed, but accidental immersion is not the same as swimming laps.

IPX ratings are rarely used for running watches anymore. Most manufacturers, Garmin included, moved to the ATM system, which is what you will see on anything current.

IPX water-resistance ratings

IPX6

Protected against heavy splashing and rain. It must not fail or show water seepage when exposed, but it is not rated for immersion at all. Fine for running in a downpour, not for anything more.

IPX7

Protected against short durations of immersion, specifically up to 30 minutes at a depth of less than 1 meter. That is a rating for surviving an accident, not for swimming. Even though the number sounds reassuring, I would not swim in an IPX-7 watch.

IPX8

Designed for continuous underwater use, and the only IPX rating that is genuinely appropriate for swimming. The manufacturer sets the specific depth and duration, so IPX-8 on its own does not tell you how deep. Check the spec sheet rather than assuming.

ATM waterproof ratings

The ATM system uses a number you multiply by 10 to get the depth rating in meters. If a watch is rated 3 ATM, that is 3 x 10, or 30 meters.

1 ATM

Rated to a depth of 10 meters. Splashes and rain only. This is uncommon on modern running watches.

3 ATM

Rated to a depth of 30 meters. Fine for rain and showering, generally not recommended for swimming laps.

5 ATM

Rated to a depth of 50 meters. This is the standard for current running watches and it is swim-safe for pool and open water swimming. If you are training for a triathlon, 5 ATM is all you need.

10 ATM

Rated to a depth of 100 meters. You will find this on adventure and multisport watches like the Garmin fenix 8, the COROS VERTIX 2S, and the Apple Watch Ultra 2. Some of these carry a separate dive rating on top of it. Unless you actually dive, this is more than you need.

One caution worth knowing: depth ratings are tested in still water. Moving your arm through water during a swim stroke creates pressure well above the static depth, which is why manufacturers draw the swimming line at 5 ATM rather than 3.

So which watch should you buy?

Since water rating is no longer the deciding factor, pick on everything else. If you are doing triathlons, what you actually want is a watch with a proper multisport mode that handles the swim-to-bike-to-run transitions in a single activity, not just one that survives the swim.

The Forerunner 265 is the one I point most triathlon-curious runners toward. It is 5 ATM, it has full triathlon mode, and it does everything you need for marathon training the rest of the year.

For anything beyond that, compare the full field in the Running Watch Finder. You can filter by triathlon mode, by budget, and by the features you actually care about, and every watch listed shows its water rating in the specs. If you are shopping Garmin specifically, we also cover which Garmin to buy.