GPS watch settings & displays for an ultra marathon

Prior to Run Rabbit Run 100, I wanted to tweak the recording settings and display fields on my Suunto Ambit GPS Watch + Heart Rate Monitor to be more optimized for an ultra marathon race. I found few recommendations online, so to fill that void I will share my decisions here.

Other GPS watches like the Garmin Forerunners and Polar M400 and V800 can be similarly customized, though I’m less familiar with the process or options.

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My well used Suunto Ambit2 GPS Watch + Heart Rate Monitor, with the Dual Comfort Belt heart rate sensor accessory

My well used Suunto Ambit2 GPS Watch + Heart Rate Monitor, with the Dual Comfort Belt heart rate sensor accessory

The changes I made reflect two key differences between a normal training run and an ultra marathon effort:

1. Battery life

At the most accurate GPS recording interval (every 1 second), my Ambit2 will last up to 16 hours; the newer Ambit3 Peak, Ambit3 Sport, and Ambit3 Run will last 20, 10, and 10 hours, respectively. This lifespan is adequate for the longest of long runs, but insufficient for most 100-mile efforts as well as some 100k’s and 50-milers, depending on both the speed of the runner and the course.

2. Pacing

During an ultra, I generally ignore the cumulative time and distance for which I’ve been racing and, instead, focus primarily on the shorter distances between aid stations (“laps”). This makes the race feel less overwhelming, and provides me with numerous opportunities to compare my splits against a pace chart that I created beforehand using data from other runners in previous years. For RRR100, for example, I created a 20-hour pace chart by adding 13 percent to each of Rob Krar’s splits from 2014. In a normal training run, my focus is generally the opposite (on cumulative data, not lap data), save for the rare track workout or tempo run.

At, which is Suunto’s online platform, I can have up to twelve “Sport” modes (plus two “Multisport” modes if you’re into that), each with customizable names, recording settings, and display fields. This prevents me from having to overwrite my most commonly used setting (“Running”) for every race (“Ultra Trail Race”) or backpacking trip (“Trekking”).

On, I can customize the settings and display fields for up to 12 sport modes plus two multi-sport modes. When I download my watch data onto my computer, the settings are automatically synced.

On, I can customize the settings and display fields for up to 12 sport modes plus two multi-sport modes. When I download my watch data onto my computer, the settings are automatically synced.

Recording interval

Select: “1 second”

This setting only affects memory storage, not battery life, I believe. And unless you will be gathering extensive GPS data with no opportunities to download it (e.g. a month-long running retreat in the boonies with no computer), my experience is that the Ambit has sufficient internal memory to record at 1-second intervals.

Moreover, if you plan to upload your data to Strava, know that anything but a 1-second recording interval will produce wonky graphs and pace calculations, as seen below. Movescount does not share this problem.

I'm a strong backpacker, but a 27-mile hike at 5:41/mile pace? I don't think so, Strava. And what's up with that pace graph? Clearly, their algorithm struggles to analyze data recorded at 10-second intervals.

I’m a strong backpacker, but a 27-mile hike at 5:41/mile pace? I don’t think so, Strava. And what’s up with that pace graph? Clearly, their algorithm struggles to analyze data recorded at 10-second intervals.

GPS Accuracy

Select: “Good – 24 hour battery life”

When I finished RRR100, my watch reported 18 percent battery life after about 20 hours 15 minutes of continuous use at 5-second GPS recording intervals. Proportionally, this would translate into nearly 25 hours of battery life (20 percent per 5 hours), so I am inclined to generally trust Suunto’s other estimates for my Ambit2: 16 hours at 1-second intervals and 50 hours at 60-second intervals. In fact, these numbers may even be conservative: I wore my heart rate monitor from start to finish, which I would assume put additional strain on the battery.

With 1- and 5-second recording intervals, the real-time data (i.e. watch display) and downloadable data (i.e. Movescount, Strava) seems reliably accurate. I have used extensively the 60-second interval, too, for slower-moving backpacking trips, and have noticed a longer delay in real-time data and jumpiness in my downloaded tracks.

If I expected to finish a race in more than 24 hours, I would consider a mid-race watch swap, a watch-less finish, or (my favorite option) a mid-race change in the recording interval before I used the 60-second recording interval. This recommendation may become outdated by a future Suunto firmware update: it is possible to improve the accuracy of the 60-second interval by better utilizing the watch’s internal accelerometer, barometer, and digital compass.

PODS to search

When paired with the Suunto Dual Comfort Belt or Suunto Smart Belt, my Ambit becomes a heart rate monitor, with which I can more effectively govern my effort and pace, especially at the start when I’m tempted by race day excitement, fresh legs and peer pressure to run at unsustainable levels. This may put me ahead of my intended pace early on, but later in the race I will hemorrhage far more time than I gained. Later in the race, heart rate data is less important, if not irrelevant — at some point, instinct and guts must rule.

To have the Ambit search for a heart rate sensor, check the “HR belt” box. It will only connect with sensors with which it has been previously paired.


The Suunto Ambit can show up to eight customizable screens, each with up to three fields. To rotate between screens, use the “Next” button (middle button, right side). While the top and middle display are fixed, the bottom display can rotate among up to five items. To change this display, use the “View” button (lower button, left side).

Intentionally, I display some of the most important data on more than one screen. This reduces the scrolling necessary to find it, and helps me put the primary focus of the screen (e.g. Pace, Heart Rate) in more context.

For my race settings, I have only four screens, the first two of which I use most often.


Screen 1: Pace

Top display

  • Lap time | To compare my actual time versus my projected time.

Middle display

  • Current pace | To better maintain a pace that is within the range of my projected pace.

Lower display

  • Lap average pace | An advanced indication as to whether I am ahead or behind my projected pace. May speed up or slow down in light of this information.
  • Lap distance | To inform decisions about pace and intake of liquids and calories.
  • Current heart rate | To put my current pace in more context — To keep this pace, am I having to run too hard, too easy, or just right?


Screen 2: Heart Rate

Top display

  • Lap time | To compare my actual time versus my projected time.

Middle display

  • Current heart rate | To better maintain a sustainable effort.

Lower display

  • Cumulative average heart rate | To understand my cumulative effort thus far, transcending individual laps during which I may have run a little too hard or a little too easy.
  • Current pace | To put my current effort in more context — At this heart rate, am I running faster or slower than, or equal to, my projected pace?
  • Lap average pace | An advanced indication as to whether I am ahead or behind my projected pace. May speed up or slow down in light of this information.
  • Lap distance | To inform decisions about pace and intake of liquids and calories.


Screen 3: Vertical

Top display

  • Cumulative ascent | To adjust pace based on how much climbing I have ahead and behind me.

Middle display

  • Current altitude | To rule out false summits and false bottoms, assuming I know the elevations of high and low points.

Lower display

  • Current vertical speed | To monitor changes in my climbing strength throughout the race. If I paced myself wisely, at the end of the race I should be able to climb at about the same rate (though with more effort) as I did at the start.
  • Cumulative descent | Less worthy than Ascent of a dedicated display since descending requires less energy.
  • Current heart rate | To control my effort while climbing. In contrast, my Current Pace is nearly irrelevant — it is affected too greatly by the exact gradient, and perhaps by my altitude, too.


Screen 4: Cumulative

Top display

  • Cumulative distance | To avoid being discouraged, I rarely look at this number until I’m in the latter stages of the race.

Middle display

  • Cumulative time | To make larger computations about my splits and pacing.

Lower display

  • Cumulative average pace | To determine if I am slower or faster than my cumulative goal pace, and by how much.
  • Cumulative average heart rate | To understand my cumulative effort thus far, transcending individual laps during which I may have run a little too hard or a little too easy.
  • Time of day | To prepare for darkness, daybreak, and high and low daily temperatures. And to better communicate with a support crew, for whom cumulative race time means less than it does for me.
  • Battery life | If my watch will die before the finish, I’d prefer that it not be a surprise.
Posted in on September 29, 2015
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  1. Randy Martin on September 29, 2015 at 9:56 pm

    Good information Andrew. I have the Ambit 2s and so have a bit less battery life but all of the same feature set. Love Ambit

    • Andrew Skurka on September 30, 2015 at 7:40 am

      Thanks for leaving a comment. I feel like it’s crickets in this post. A niche of a niche: runners who do trail ultras, and ultra runners who have a GPS watch.

      • Alice on December 26, 2016 at 11:30 am

        what do you think if hand held GPS for ultras

        • Andrew Skurka on December 26, 2016 at 11:47 am

          It would give you accurate cumulative distance and time (but maybe not split distances or time) and speed (but probably not pace). And it would not be as conveniently wearable as a watch.

  2. Ultramarathon Daily News, Wed, Sep 30 on September 30, 2015 at 7:39 am

    […] Speaking of GPS devices…interested in altering the settings in your Suunto for an ultramarathon? […]

  3. Paul on September 30, 2015 at 8:59 am

    Great stuff man. I have always raced without my GPS watch but have been weighing pros/cons of using it for next season in order to try to better gauge my efforts, be more competitive, and have better data after a race to recap. I have the Ambit so these settings are just what I was looking for. Thanks!

    I don’t train with HR so I’ll be using it more for pace, distance and time displays.

    This might be a huge can of worms, or you may have already posted about it and I missed it, but any recommendations for how to set splits for a race. I have a tendency to pick races that are new and don’t have much data from past racers to go off of.

    • Andrew Skurka on September 30, 2015 at 9:36 am

      I would highly recommend getting a heart rate sensor. For an extra $60 or $80, I think that you double the value of the watch. Pace and distance calculations are nice to have, but heart rate is a much better indicator of effort in a mountain trail race. I wish that I had not waited 12 months before getting a HR belt for my Ambit.

      Re split charts, you might want to read this post:

      Maybe I’ll write a separate post on this topic, but the basic steps to create a split chart:
      1. Find data. Official splits are good, but few trail races have the infrastructure to record and post these. Plus, you don’t know exactly where the split was taken — before the aid, in the aid, after the aid? So I normally pull the data off Strava.
      2. Drop all the data into a spreadsheet, in the HH:MM:SS format. You can use splits of one runner who ran a smart race, or you can average a few runners. The latter is probably best, as it will give you a smoother pace, instead of capturing when a lone runner went to the bathroom, swapped out their shoes, etc.
      3. Add or subtract a proportional amount of time to their splits, in order to get your goal splits. In RRR100, for example, I added 13 percent to Krar’s splits. And for TNF EC50 last December, I took Dylan Bowman’s finishing time from 2013 (6:37) and extrapolated them out for a few different times.

      If you have entered a new race, there are a few ways you can pace yourself:

      1. In a mountain trail race, the average vertical gain/loss per mile is the best measure of the speed of the course, much more so than distance. Basically, the more vertical per mile, the slower the course. Of course, the technical nature of the terrain and the altitude matter, too. By analyzing your training runs, you should be able to ballpark your finishing time. I did that with TNF last year:

      2. Get a heart rate monitor and start wearing it during training runs and races, especially races. Then, early in the race, keep your HR within the range of what you deem to be a sustainable average HR. Last year I wore my HRM at TNF and recorded 142 bpm average. In two months, I will wear it again, and I will keep my HR at around 142 in the early stages of the race, maybe just a little bit higher.

      • Paul on September 30, 2015 at 12:30 pm

        Thanks man. Always appreciate the work you put into your planning and the analytical side of your adventures.

      • Paul on October 6, 2015 at 12:49 pm

        Alright man, made the move and bought the HR belt. Looking forward to getting used to it over the next few weeks and then utilizing it once I start ramping back into training.

        Thanks again for all the advice!

  4. Bryan on September 30, 2015 at 9:01 am

    I used my recently acquired Ambit2 at Wasatch 100 a few weeks back. I had it on 1s recording interval and 1s gps accuracy. About halfway through the race, I grabbed an USB battery and the watch charging/syncing cable and was able to charge it up during my run. You can just hold the battery in your hand like I did, or create some pocket or something on your sleeve. After a few hours, it was charged back up to 100%. It successfully tracked the whole race and didn’t drop the GPS tracking when plugged in like my Soleus did or like my friends Garmin does. For us 30 hour finishers, the only other option is to switch to 60s GPS accuracy, which I didn’t want to do.

    • Andrew Skurka on September 30, 2015 at 9:16 am

      Funny, I was going to suggest a mid-race recharge as another option but I didn’t: personally I would never be willing to carry a 4-oz charger + charging cable, and deal with the fuss factor while trying to race. But now that I think about it more, the effort could be worthwhile: if your watch dies at 16 hours and you’re striving for 30 hours, that’s a long way to race without a watch if you are accustomed to having it.

      BTW, you might want to consider the 5-second GPS interval. It would get you out to at least 24 hours with minimal loss of GPS accuracy. And in the last 6 hours of the race, you’re probably moving much more on how you feel than what your watch is telling you.

      • deitemiller on October 1, 2015 at 8:07 am

        I ran the RRR 100 – finished in 30:08 – yea I know how many points in the race could I have picked up 8 minutes for the gold buckle! But it was my first 100 and I’m happy.

        Had my Ambit 3 set at 1s intervals and GPS accuracy at Good – 30 hr battery life. This proved accurate, Strava data good and my watch had 4% battery life left when I crossed the finish line… and Andrew was there showered and fine even though having started 4 hours after me!!

  5. Pete Rodrigues on September 30, 2015 at 9:48 am

    Thanks Andrew. This was very helpful – even if it is a niche.

  6. Steve on September 30, 2015 at 2:32 pm

    Great article. I just received my Ambit3 Peak. I have a 100K on Saturday and have only had a couple runs with the Ambit to figure out all the features. I expect a 13+ hour finish time. Would you put the GPS accuracy at 1 sec or 5 sec? Also, being a former Garminite, I am used to the mile splits beeping and the display showing that mile split. Is this feature available on the run or do I have to wait until post run and see my splits on Strava?


    • Andrew Skurka on September 30, 2015 at 2:41 pm

      Most definitely, use the 1-second GPS recording interval. The Ambit3 Peak has enough battery life for 20 hours at that setting, and since your watch is brand new I would expect no issues at all in reaching that; even my 2 year-old Ambit2, which gets nearly daily use, was on pace to go further than Suunto estimated it should.

      I am unaware of any setting to get a 1-mile beep, at least on the Ambit2. However, you might look for an aftermarket Ambit app with this functionality.

  7. Derrick Spafford on September 30, 2015 at 2:35 pm

    Great post!

    One of the things that I’ve found helpful for ultra use for longer races with regards to battery life is to make 3 different ‘Sport Mode’ options with the identical settings except that the first sport mode is ‘Best’, second is ‘Good’ and third is ‘ok’.

    Start with the ‘Best’ Sport mode for the first half (or more) of the race when it is most important to monitor effort and chances are you’ll be moving quickest. Have the battery percentage visible on all sport modes and keep an eye on it. If you find that depending on your time you are going to need more battery life, you can easily switch from ‘Best’ to ‘Good’ mode during the race. Then if you’re still out longer than planned, you can switch to ‘ok’ mode if needed too. You can switch between these by holding the top left button and selecting your option.

    This just give more possible options if you want the most accurate data at the beginning, but can still utilize the suggestions that you made too.

    • Andrew Skurka on September 30, 2015 at 2:50 pm

      Great idea, and an option previously unknown to me! In fact, it’s the best idea I’ve heard for those wanting to use their watch for the duration of a race but not having the battery power at 1- or 5-second intervals to do so. Less expensive than having a second watch, more convenient than a mid-race recharge, and more accurate than 60-second intervals for the entire race.

      For those considering this idea, know that the Ambit will last a long time on the 60-second interval. I use this setting on my backpacking trips, when I keep my watch running for 12-14 hours per day and recharge it every 3-4 days. Using Suunto’s battery estimates for my Ambit2 (50 hours), you get 1 hour of recording per 2% battery life. In theory, you could run the watch down to 10%, change the recording interval to 60 seconds, and go another 5 hours before your watch dies.

    • Hecke on October 1, 2015 at 5:42 am

      Derrick, thanks for this idea. I played quite a bit with my Ambit2S (unfortunately I had no idea I would be running for more than 8 hours when I bought it…) so most of the tips from Andrew (thanks anyway for the post, I like it!) were already known, but this on the fly switch of sports modes is new to me. Will construct an emergency mode immediately 😉


  8. TraceyTA on September 30, 2015 at 5:36 pm

    Thankyouthankyouthankyou for this post! After throwing my Garmin against a wall, really, that thing drove me nuts until it died, I bought a Suunto Ambit3 and have been putzing around with the settings and screens. There is a bit of a learning curve coming off Garmin, so many thanks for shortcutting it for me! Huge congrats on RRR!

  9. Mike Hugus on September 30, 2015 at 7:59 pm

    Wow, I just got the HR belt a few days ago and poured over the web trying to find some info, only to come up with lackluster results. I could have really used this.

    I too came to the idea of having the same piece of data on multiple screens to apply context to the information. Thanks for writing this up. This post should now become the go-to for Suunto watch setup.

    And am I the only one that thinks Suunto could use a little polishing to the user interface with this watch/movescount? In my opinion, it’s not the most intuitive.

  10. Chris Gkikas on October 1, 2015 at 5:34 am

    Great article! Now I know how to program my Ambit3 Peak and not feel like an idiot for barely using this expensive gadget’s features.

  11. deitemiller on October 1, 2015 at 8:38 am

    Andrew, I have always had my trail running and running modes set at auto lap of 1 mile. You are describing here a lap which is set based on specific points in the race – in this case certain aid stations for your splits. Is it correct that you have auto lap turned off, and you are then hitting the top left button (back lap) to record the end/start of these laps? And then all your lap data relates to those manual laps? I can try this but elaboration may be helpful for others.

    • Andrew Skurka on October 1, 2015 at 9:09 am

      Yes, correct. Auto-lap is off, and I record manual splits at locations I have identified beforehand. My pace chart for RRR100 is below.


      Below, TNF EC 50 last December. I prefer my RRR100 chart, versus this one. You don’t need multiple pace columns — just pick one, and do some simple addition/subtraction to determine where you stand (“Okay, at the Mi 34 aid I’m 8 minutes off 7:15 pace.”) Multiple columns just gets confusing. Also, I like the addition I made of the aid station names, since this is how they are normally talked about.


  12. Jason on October 1, 2015 at 1:51 pm

    Very cool – I have an Ambit 3 Sport and I had no idea I could adjust the settings like this. Basically, I have a BMW and I’ve never taken it out of the driveway… I might even invest in the HRM now… good stuff!

  13. Jerod Tufte on October 2, 2015 at 9:26 am

    great post. I’ve got an Ambit2 and have developed a similar approach. One thing to pay attention to is that if you use any apps, make sure that you are not logging the data, or your watch might just run out of storage. on a 25-hour 100mi race last year, I’d had it logging data from two apps and it filled up the watch and although the watch appeared to work great all the way when I looked at the recorded data the end part of the race was simply gone.

  14. Jules on October 27, 2015 at 12:44 pm

    fantastic post, used the recommendations on my Ambit3 Peak for my race on Saturday. I was aiming for under 24hr finish, so set GPS accuracy for Good/30hrs. However it only lasted 18hrs.
    I looked at the settings after the race and the cause of the premature battery fail, could be either using the HR strap, or using two apps (How Hard, a % HR app, and distance to next WP), both of which were logging data. Or maybe a mixture of both?
    Does anyone have any thoughts on this or experience? The mists came down halfway through the race, and I was half relying on the navigate feature, so any way to avoid this again would be good.


    • Andrew Skurka on October 27, 2015 at 2:37 pm

      A few options:

      1. It’s the HRM. I’m doubtful of this. I ran RRR100 with my HRM, and there seemed to be no significant effect on battery life, as determined by what Suunto estimated (24 hrs at 5-sec intervals) versus what actually happened (finished in 20 hours with 18 percent battery left, which translates into 25 hours).

      2. You have a faulty battery. I’m doubtful of this, too, or you’d be hearing about it.

      3. It’s the extra apps you installed. I would check their settings. If they are activating the GPS every 1 second, that would explain why your battery life was almost half of what you expected it would be.

      • Jules on October 27, 2015 at 3:56 pm

        1, just needed confirmation that the HR function wasn’t a big drain. 2. I agree doubtful that I have a faulty battery, ‘normal’ usage doesn’t drain the battery. I’ve never got it below 70% in a an average running week.
        3. Investigating further the apps that I used revealed the distance to next waypoint app does access the GPS every second to get the result (distance). The HR app is just a % calculation, so I don’t think that’d burn through the battery.
        I think next time I’ll have to memorise the distance between aid-stations!


  15. mtrun on December 9, 2015 at 9:48 am

    Enjoyed this post.

    Could you also shed some light on your altimeter settings? I also use an Ambit2.

  16. Karlie on October 11, 2016 at 10:33 pm

    Thanks so much for this post! It was really, really helpful for me in setting up my Suunto watch. I appreciate all the advice!

  17. Hugo on January 25, 2017 at 1:10 am

    Thank you for sharing this. I’m on my way to my first ultra (Columbus Grand Trail ) and setting up my watch is one of the things that was really buggin me. This is gold.

  18. Dave on August 2, 2017 at 9:10 am

    Great article Andrew. Thanks so much! Getting ready for the 58k Moosamaloo in Vermont this weekend and your advice is gold. So very much appreciated.

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