Best watches for a first triathlon

A first triathlon needs one button press that moves the watch from swim to bike to run. Plenty of watches can't do that. The Forerunner 170 logs open-water swims and still has no triathlon profile, so it isn't here.

I haven't worn any of these. The figures below come from maker pages, checked on 3 November 2026, and every battery figure is a manufacturer claim. If you'd rather start from your own training, the picker does that, and the triathlon goal page lists the wider set.

How long your race really is

Distances vary by organiser, so check your race. These are the usual ones.

The longest of those has the only time limit worth planning a battery around. A 70.3 cut-off is commonly 8 h 30 min from the start, according to Wikipedia's entry, and your race's athlete guide has the figure that counts. I couldn't get a current official IRONMAN page to answer on this.

Which watches cover it

Take that 8 h 30 min as your worst case.

Those modes differ, so they're not a like-for-like race. Only the Apple figure gets close. Its claim beats the 70.3 limit by about 1 h 30 min, which is fine for a sprint or an Olympic and uncomfortable for a slow middle distance. Everything else clears it by a long way, even in multi-band on the Forerunner 570.

So battery isn't what separates the top four. Sensors are.

Check your sensors before you buy

This catches people out. If you already own a power meter or a strap that only speaks ANT+, then the Polar Vantage M3 and the Coros Pace 4 won't connect to it, because both list Bluetooth only. Apple lists Bluetooth cycling accessories.

The two Garmins take both. Starting from nothing, this doesn't matter much: buy Bluetooth kit. The practical steps are in how to connect a chest strap, and the closest head-to-head is Polar Vantage M3 vs Forerunner 570.

What nobody has shown about the swim

Here's the gap. I found no independent peer-reviewed test of open-water distance for any watch on this page.

Gilgen-Ammann 2020, peer-reviewed and part-funded by Polar, is the nearest GPS study I read. It tested eight watches from the 2019 era for walking, running and cycling, with average distance errors of 3.2% to 6.1%. None of these five was in it, and it doesn't tell you what happens when your wrist goes under water every second.

Heart rate in the water is the same story. I have no verified figure for wrist sensors during swimming on any of these models. On dry land, Zhang 2020, a peer-reviewed meta-analysis of 44 articles and 15 brands, found wrist readings a mean of 4.55 bpm low on the bike and 0.51 bpm low on a treadmill. Those are averages across older models, and individual errors run larger.

If swim heart rate matters to you, Garmin says its HRM 600 chest strap stores swim heart rate and forwards it later. I'd only bother for a longer build.

Remember that a tracker isn't a medical device. These readings are estimates for general fitness and wellness, and if you have symptoms or concerns, talk to a clinician.

What I'd buy

For a sprint or Olympic and an iPhone you already own, the Series 12 is enough. Most people aiming at a 70.3 and holding older ANT+ kit should look at the Forerunner 570.

Starting clean, I'd pick the Pace 4 for the weight and the hours, and the Vantage M3 if you want maps for a bike course you've never ridden. Thinking past 70.3 already? Then read best watches for ultras and Ironman first, since those hours work differently.