A little less than a year ago, I switched from the Suunto Ambit 2 watch to the brand-new Suunto 9. Suunto Ambit 2 was and is an extraordinary watch. It’s durable, simple to use and very accurate when it comes to GPS tracking. Furthermore, the battery life is just amazing. I was using the watch daily for no less than four years and I haven’t noticed any signs of deteriorating battery life. Suunto 9, on the other hand, is a bit more complex watch. It has more features; some of them useful (wrist HR, in-depth activity tracking etc.), others not so much. Ever since I bought the Suunto 9 , I’ve been wondering how accurate its GPS tracking is in comparison to the Suunto Ambit 2.

Suunto Ambit 2 offers incredibly accurate GPS tracking due to its powerful, but ugly, external GPS antenna. In four years, I had problems with GPS tracking only once when we were climbing a mountain in the Alps from a very narrow valley. The watch couldn’t acquire the GPS fix until we were half way up. Besides from that, the tracking was always surprisingly accurate. When I switched to Suunto 9, I noticed that GPS tracks made by the watch look a bit less accurate than those from Ambit 2. However, the total distance and ascent never differed much. Therefore, I decided to take both watches for a spin and see which one provides better GPS accuracy. But let’s first explain the GPS technology behind both watches and how the GPS accuracy tests were conducted.

Suunto Ambit vs Suunto 9:

GPS Technology of Suunto Ambit 2 and Suunto 9

The main difference between the watches are their antennas. Suunto Ambit 2 has an external antenna while Suunto 9 has an internal (bezel) antenna. It is safe to assume that Ambit’s external antenna has better performance than the bezel antenna of Suunto 9. I guess Suunto decided to eliminate external antennas from the design of their newer devices since many complained that they are bulky, and well, ugly (see image). Besides from the antenna, both watches only support GPS and not also other positioning systems such as GLONASS and Galileo. It is indeed a bit disappointing that Suunto’s top tier watch (Suunto 9) doesn’t support GLONASS or Galileo. Suunto 9 supports GLONASS since November 2018 and Galileo since July 2019. The watch was equipped with the hardware from the beginning but didn’t have software support for it. Suunto added support for GLONASS and Galileo very quietly via software updates and I didn’t even know that the watch supports them. GLONASS and Galileo allow the watch to connect to more satellites and in theory increase the tracking accuracy.

How did I test the GPS accuracy?

I wore both watches at the same time on nine different runs. On the first four runs the Suunto 9 watch was in GPS-only mode and on the next three runs in GPS + GLONASS mode. On the last two runs I tested the watch in GPS + Galileo mode. Both watches were set to a 1-second GPS tracking interval and I waited for both watches to acquire GPS fix before I started running, Some test runs were conducted in dense woods, while others were conducted in more or less suburban neighborhood. It is obviously easier to assess GPS accuracy while you are running on a road – if the track goes off road on the map, the GPS tracking is obviously not accurate. After the test runs, I exported the GPS tracks from Movescount and used GPS track tools to compare them. Below are the results.

Test run 1

Total Distance – Suunto 9: 6.13 km

Total Distance – Suunto Ambit 2: 6.17 km

Clarification:

This test run was conducted on terrain covered with dense woods and on the image above it’s clearly seen that both watches struggled with GPS signal. However, the total distances differ for only 40 meters which is really not a lot (<1%), taking into account that the total distance was more than six kilometers. After I thoroughly inspected both tracks, I concluded that Suunto Ambit 2 produced a better GPS track. See the image below.

Here I was clearly running on the road towards south until I took a side path into the woods towards east. Suunto Ambit watch nicely followed the road while Suunto 9 watch is off the road for at least twenty meters.

Test run 2

Total Distance – Suunto 9: 5.08 km

Total Distance – Suunto Ambit 2: 5.03 km

Clarification:

This run was conducted on relatively open terrain without woods or any other obstacles that could impair GPS accuracy. As you can see both tracks are very similar. Nevertheless, after thoroughly inspecting them, I again concluded that the Ambit watch produced a more accurate GPS track. However, note that we are talking about several meters here – see the image below.

Here I was running towards west on the sidewalk on the left side of the road. Clearly the Ambit 2 watch is closer to the sidewalk than Suunto 9 which basically shows me running inside people’s gardens. The total distance of both tracks differs for 50 meters (≈1%) for a total distance of 5 kilometers which I find more than acceptable.

Test run 3

Total Distance – Suunto 9: 8.16 km

Total Distance – Suunto Ambit 2: 8.37 km

Clarification:

Now, this run is interesting because I was running from a very open suburban terrain to dense woods (right side of the image) and that is clearly seen on the GPS tracks. Before I reached the wooded area, the tracks are almost identical but then they start differing. I took quite some time to inspect these two tracks, but I can’t say which one is more accurate. Ambit 2 watch obviously had some problems on the road before Aktivitetscenteret Peter Sabroes Minde (teal pin, right side of the image) because the track is bouncing a lot there while the road is indeed relatively straight. However, the Suunto 9 watch obviously struggled on the stretch in the detail screenshot below. I know this stretch well and the Ambit watch indeed got it more precisely. In terms of total distance, the two watches differed for 210 meters (≈2,5 %).

Test run 4

Total Distance – Suunto 9: 5.35 km

Total Distance – Suunto Ambit 2: 5.39 km

Clarification:

The last test run is very similar to test run two and takes place on a relatively open terrain. I decided to do another test on open terrain to confirm my assumption that obstacles such as dense woods have big impact on GPS accuracy. As you can see on the image above both tracks are very similar which tells us that both watches were accurate. However, I can say that the Ambit watch was slightly more accurate.

Now, obviously I didn’t run over the building as the red Ambit track indicates, but I did run very close to it and thus I find the Ambit track more accurate. Furthermore, when I reached the road in the top part of the picture I was running on the right side of the road and the Ambit watch indeed followed me accurately. However, do note that we are talking about a few meters here and this indeed doesn’t mean that Suunto 9 is imprecise.

Test run 5

Suunto 9 with GLONASS enabled

Total Distance – Suunto 9: 15.87 km

Total Distance – Suunto Ambit 2: 11:43 km

Clarification:

So, when I figured out that Suunto 9 actually does support GLONASS, I was excited to test the tracking accuracy in GPS + GLONASS mode. The excitement quickly cooled. After running for several kilometers, I noticed that something is just not right. The Suunto 9 watch showed that I’m running with the pace of 3 min/km which of course wasn’t true – I’m not Usain Bolt. As seen above, the tracking accuracy of Suunto 9 watch was terrible (as per my apparent route at sea), while the tracking of Suunto Ambit 2 was very good. I’ve never experienced such a bad tracking with Suunto 9 before enabling GLONASS. So, my guess is that the GLONASS functionality is not yet fully developed. The difference in total distance between the watches was no less than 4.4 kilometers. Therefore, I decided to conduct two more test runs with GLONASS enabled to see if such this error is common.

Test run 6

Suunto 9 with GLONASS enabled

Total Distance – Suunto 9: 6.64 km

Total Distance – Suunto Ambit 2: 6.60 km

Clarification:

As the test run 5 was conducted on tricky terrain (dense woods), I decided to do the next test run on a more open terrain. Despite that GLONASS was enabled, the Suunto 9 watch followed me accurately this time. Not as accurately as Suunto Ambit 2, but I consider the result satisfactory. In terms of total distance, the two watches differed for only 40 meters over the distance of more than six kilometers.

Test run 7

Suunto 9 with GLONASS enabled

Total Distance – Suunto 9: 7.24 km

Total Distance – Suunto Ambit 2: 7.30 km

Clarification:

For the last test run with GLONASS enabled, I decided to take the watches to dense woods again. To my surprise, Suunto 9 didn’t have any problems this time. Both watches followed me accurately which is clearly seen from the image above. The total distance between the watches differed for only 60 meters over the distance of more than seven kilometers which is indeed great.

Test run 8

Suunto 9 with Galileo enabled

Total Distance – Suunto 9: 4.08 km

Total Distance – Suunto Ambit 2: 4.07 km

Clarification:

When Suunto added support for the Galileo positioning system to Suunto 9 I was eager to test the GPS accuracy in GPS + Galileo mode. To my surprise, Suunto 9 watch produced a very accurate GPS track in GPS + Galileo mode. In terms of total distance, the two watches differed for only 10 meters over the distance of more than 4 kilometers. Well, that could have been pure luck, so I decided to conduct another test in GPS + Galileo mode.

Test run 9

Suunto 9 with Galileo enabled

Total Distance – Suunto 9: 5.06 km

Total Distance – Suunto Ambit 2: 5.12 km

Clarification:

On the second test run with Galileo enabled, the two GPS tracks differed for 60 meters over the distance of approximately 5 kilometers which I find great. After thoroughly inspecting both GPS tracks, I couldn’t really say which one is more accurate; both are very similar. However, I got similar results when comparing Suunto Ambit 2 tracks to Suunto 9 GPS tracks in GPS-only mode. Therefore, I’m not convinced that GPS + Galileo does much in terms of accuracy. However, the watch might get satellite fix faster in this mode, simply because more satellites are available.

The annoying Suunto 9 bug

I’ve been using the watch for almost a year now and I did notice that the watch sometimes gets confused when you start recording an exercise. It doesn’t happen often – I guess once per twenty workouts at most – but it is freaking annoying. So, the watch doesn’t start tracking immediately but after a kilometer or so and this distance won’t be shown in the Movescount app. However, the watch will still calculate the distance relatively precisely. See the image below for better understanding.

So, the Movescount app shows the starting point and the distance at the starting point is already 1 kilometer. That is, however, not the starting point. The first kilometer of the track is simply not shown.

Conclusion

So, which watch has a better GPS performance? After all these tests I think that the Suunto Ambit 2 watch is slightly more accurate. However, also the Suunto 9 watch provides a very good GPS performance, especially considering that it has an internal bezel GPS antenna. If we exclude the test run 5 where Suunto 9 had some weird (GLONASS?) issues, the biggest difference in total distance between GPS tracks was only 210 meters (total distance of more than 8 kilometers).

Now the big question is whether you should enable GPS + GLONASS or GPS + Galileo tracking on Suunto 9 – or not. After all these tests I concluded that GLONASS and Galileo make no positive difference in tracking accuracy and therefore I recommend using the watch in GPS-only mode. Before enabling GLONASS I’ve never encountered as inaccurate a tracking on the Suunto 9 as on the test run 5. Therefore, I believe that the inaccuracy was connected to GLONASS. However, note that I conducted three test runs with GLONASS enabled altogether and only one of them resulted in inaccurate tracking. But that one was so terribly inaccurate that I probably won’t enable GLONASS again anytime soon. I also contacted Suunto support regarding the issues with GLONASS. Their reply was as follows: “It is not recommended to use both GLONASS and GPS at the same time. It can record wrong and zigzag GPS data. Glonass is suitable for cities with large buildings and other obstacles that may affect our GPS signals.”

What do you think? Leave your thoughts in the comments section below.

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Post Author Blaz Outdoor enthusiast with experience in all types of hiking and mountaineering. Hiked in the Alps, Iceland and other countries. In love with via ferrata trails and snow-covered slopes. Check out my hikes.

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