Best Ultra Running Watches: Recommended GPS Watches for Ultramarathons, 2021 Edition

In this post, I share the best ultra running watches on our radar, and give you some pointers on what to look for in a GPS watch for your ultramarathon!

Finding a good GPS watch for your ultramarathon – the training and the race itself – requires some research.   

The requirements of an ultramarathon GPS watch are way different from your regular GPS watches. A marathon GPS watch might not go the distance when it comes to ultras.

For example: for my day-to-day activity tracking I actually tend to use my Apple Watch.   It’s functional, it syncs with my iPhone, and the GPS and Strava app are decent-enough quality. I even use it for logging the occasional short run.  But, it’s not designed for distance running. The battery life craps out after around 4 hours, and the metrics it produces aren’t as reliable.

Once you’re into ultra-distance runs, you need a GPS watch that has great battery life, as well as reliable GPS tracking, and other features like HR monitoring so you can track your training progress.

Let’s look at some of these features: 

What I Look For In An Ultramarathon GPS Watch

Battery Life

Battery life is a key feature of an ultra-running watch.   Most regular GPS watches on the market are good for 8 – 10 hours, then you’re on your own.  

So finding a GPS watch that boasts and extended ‘GPS Active’ battery life is essential.   You should also consider the length of ultras you’re running, and the maximum time you’d expect to be out in the field.

An important factor to consider is the ‘sample frequency‘.   

This is how frequently the watch checks your position.

A regular GPS watch will record your position every second; however some will have different settings to allow you to extend this to up to once every minute, in order to extend the battery life.   

While this is a great feature, it leads to less accurate real-time position / speed data when you’re on your run.   So be aware that when a watch advertises “up to 50hrs battery life”, you should check the sample rate of those 50hrs.

The most suitable and best ultra running watches will include an ultrarunning mode, where the GPS signal is sampled less frequently (such as the UltraMAX mode on the Coros APEX) which can extend the battery life by 200-300%.

Actionable Metrics

In other words, these are things the watch tracks which give you information about your performance.  A watch with a heart-rate monitor is useful, especially if you have been tracking your HR in training runs, or are training based on HR zones. Frankly, I just like having that data available and stored automatically – it’s not something I analyse after every run, but every few weeks I’ll scan over how it’s tracking.

Altitude is also useful, as you can pace your efforts dependent on the difficulty of the gradients.

Finally, some navigational features can be useful (dependent on the nature of where you run, or your race).   I recently ran a self-navigated trail race where the race director sent me the trail route as a data file before the race began.

Ability to Re-charge While Running

Even the best ultra running watches crap out eventually. I always try to choose a watch that has a battery life almost guaranteed to last longer than my runs, but when you get into really long ultramarathons and multi-day stage races, the ability to recharge the watch on the move might be something worth considering.   Several watches still function while being re-charged: good models include the Garmin Fenix 6 series, the Suunto Ambit Peak, and the Suunto Spartan series.

More recently, some models of the Garmin Fenix 6 series have incorporated thin solar panels in their design, which can at least stem the depletion of the watch battery.

Good Software Platform

Modern technology gives us the ability to go back through the data of our running GPS watches and analyse every aspect of our run.   

Thankfully, you don’t have to be tied to the software platform of one manufacturer – practically all the best ultra running watch manufacturers these days allow you to automatically export workout data to 3r party platforms like Strava.

Comfort and Durability

A good GPS watch should also be comfortable for wearing while running for hours on end, and durable enough to withstand the hours of knocking and sweating they’ll inevitably be exposed to.   All the watches I recommend below fall into these camps. 

Added bonuses like the ability to sync over wifi, play music, etc. all come down to personal preference and budget.

The Challenger Brand: Coros APEX Ultrarunning Watch

Coros are relatively new to the world of ultrarunning GPS watches, but they’ve made a significant impact and have been adopted by some of the top names in ultrarunning.

Their Coros APEX watch is my current go-to GPS device for ultramarathon running; it’s battery life is ridiculous (up to 100hrs in the UltraMAX mode), and the price point is around HALF of other premium ultrarunning watches.

Check out my in-depth review of the Coros APEX here.

The Garmin Fenix series for ultramarathons

The Garmin Series 6 range are really leading the way these days for ultramarathon watches.   Though expensive, they are top performers in every feature and are packed with extras.

Here’s a breakdown of the range:

Garmin Fenix 6S Pro

The smallest of the Fenix 6 range, the 6S PRO boasts a GPS battery life of up to 25hrs, or 50 hrs in ‘UltraTrac’ mode (lower sampling rate).   

It also can store up to 500 songs, and has navigational maps. The ‘S’ stands for small – at 42mm, it is well suited to women, or thinner-wristed runners (like myself!).

Garmin Fenix 6 Pro

The most popular watch in the series, the Fenix 6 Pro boasts a GPS life of up to 36hrs, or 72hrs in UltraTrac mode.   

Note that listening to music roughly halves the watch’s battery life.   Like the other watches in the series, it even features ‘Garmin Pay’ contactless payment system!

Garmin Fenix 6X Pro

The ‘X’ is the best-in-class watch in the range, for the serious distance runner.   Boasting up to 60 hours of GPS time (or up to 120 in UltraTrac mode), as well as a blood-oxidation monitor for sleep improvement and altitude acclimation monitoring), the ‘X’ is slightly bulkier than the other two watches in the line.

Suunto Ultramarathon GPS Watches

Suunto 9 Baro

The Suunto 9 Baro watch really stands out in terms of potential battery life.   By using it’s Intelligent Battery Mode, you can be tracking your activity for up to 120hrs before this thing will die on you.   

The secret behind this is the ‘Fusedtrack’ technology – the watch checks your GPS position less often than it regularly would, and uses it’s sensors and algorithms to adjust and ‘fill in the gaps’.  Field reports suggest this technology is pretty reliable and getting better.   One for the 100-milers!

Suunto Spartan Trainer

On the cheaper end of the ultramarathon GPS spectrum, the Suunto Spartan is built for a variety of activities. 

There’s no HR monitor built-in (though you can purchase an optional HR chest strap), and the watch has a maximum GPS life of 26 hours – though it maintains a good sample rate of 1 second. 

Which features are important to you when choosing a new ultra-running GPS watch?

Which model are you currently running in?

Anything to recommend to me?

Leave a comment below!

Thomas Watson

Thomas Watson is an ultra-runner, UESCA-certified running coach, and the founder of MarathonHandbook.com. His work has been featured in Runner's World, Livestrong.com, MapMyRun, and many other running publications. He likes running interesting races and good beer. More at his bio.