We stress-tested the Apple Watch Ultra at Chicago Marathon

Testing GPS accuracy at one of the world's toughest races
Apple Watch Ultra with medal
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When Apple announced the Apple Watch Ultra back in September, one of the many features it talked up was a new dual-frequency GPS mode.

So what exactly is dual-frequency GPS and why is it such a big deal?

While it's not a new feature for smartwatches and sports watches in general, it's new to the Apple Watch.

Dual-band improves the accuracy of positioning data in challenging environments, such as wooded areas or cities filled with towering skyscrapers.

The Apple Watch Ultra is capable of communicating with major satellite navigation systems and can communicate using L1 and L5 bands.

It can lock onto both of those bands to ultimately enhance positioning data accuracy, which along with Apple’s own algorithms, can also influence the accuracy of the information like pacing and route data for runners for instance.

Putting it to the test

So what would be an ideal scenario to put this feature to the test? A marathon that’s renowned for spotty GPS thanks to its abundance of towering buildings perhaps.

Fortunately, when that Watch Ultra announcement was made we were around a month away from stepping on the start line of the 2022 Bank of America Chicago Marathon, a route that notoriously plays havoc with runners’ GPS watches.

We decided to strap on the Apple Watch Ultra and the Garmin Epix, a watch we’ve experienced a great run tracking time with recently to see how they both held up at a marathon renowned for spotty GPS. Here’s what happened.

Getting set up

Before getting on that start line, there’s one thing you need to do to increase that tracking accuracy and that’s to turn on the Precision Start mode.

If you’ve used an Apple Watch before to track a run, starting a tracking session will initiate the 3, 2, 1 countdown and the Apple Watch will start tracking your movements. 

With Precision Start in use, the Ultra will wait until it has successfully locked onto a GPS signal giving you a clear heads-up that the Ultra is ready to start tracking.

You’ll be able to tell that Precision Start is enabled because when you go to track a run, a small arrow will appear in the top corner of the screen and flick around while it locks onto a signal and then becomes stable.

To enable Precision Start, the quickest way to do it is to go to the Settings menu on the Ultra > Workout settings. Tap the toggle button next to Precision Start and when you return to tracking a workout, that arrow will now appear on the screen.

The test run

Before getting out to Chicago we decided to put the Ultra to a shorter race test at the River Ness 10k in Inverness to get a sense of what might be in store for us.

We had the Ultra on one wrist and the Epix 2 on the other and were pleased to see that the Epix 2, which had performed so well for us in general on the GPS front, had a pretty good match with the Apple Watch Ultra. It didn't nail that 10km distance exactly, but it wasn't far off.

River Ness 10k GPS test: Apple Watch Ultra (left) and Garmin Epix 2 (right) 

Then the Chicago Marathon taster came in the form of the Chicago 5K, which takes place the day before the marathon and for most runners is used as an all-important shakeout run to get the legs moving and give a sense of what’s to come.

That 5K course takes place in downtown Chicago, which means running in close proximity to some of the same buildings that feature on the full marathon course.

We decided to take both the Apple Watch Ultra and the Garmin Epix out for that shakeout run as well, using the Epix in its new multiband mode, which we’ve found has delivered some of the most accurate positional data in our most recent tests and in our Garmin Epix review.

The data above shows you how both watches captured that 5km run. The Apple Watch Ultra recorded the 5km run as a 5.25km run with an average pace of 4.54min/km. The Garmin Epix in comparison clocked the run at 5.54km with a quicker average pace of 4.40min/km.

Drilling down into the splits and it doesn’t take too long to see that the Garmin has come into some problems here and has incorrectly clocked us going at a pretty speedy 3.51 min/km pace for the third kilometer of the run, while the Apple Watch Ultra sees things differently and arguably more reliably on the splits front.

Chicago 5k GPS tracks: Apple Watch Ultra (blue) and Garmin Epix 2 (red)

A closer look at the mapped routes though and it’s pretty clear that the routes plotted for both watches aren’t exactly perfect and seem to struggle with reliable tracking in the same places. 

The Marathon test

The Apple Watch Ultra puts in an okay performance in the dress rehearsal, so how did it do for the main event? Actually not too bad at all.

According to the official Bank of America Chicago Marathon race results, we finished with a time of 3.35.05, which also usefully gives us a breakdown of splits for every 5km to get a sense of how well both the Ultra and the Epix performed against the chip-based timing.

On the Apple Watch Ultra, we stopped our watch at 3.35.08 with a distance of 42.75km and an average pace of 5.02 min/km.

We stopped the watch on the Garmin Epix at 3.35.10 with the distance recorded as 43.29km and an average pace of 4.58 min/km.

So a little closer on average pace, but certainly a bit more of a disparity in the overall distance recorded.

Interestingly, Garmin’s grade-adjusted pace data was captured at 5.03 min/km, getting it much closer to the Apple Watch Ultra’s pacing.

Digging into the splits, which we can also compare with the splits captured by the timing mats on the course and we can see that there’s inconsistency with both watches in comparison to the pacing captured out on the course.

Chicago Marathon splits compared: Apple Watch Ultra (left) and Garmin Epix 2 (right)

The Apple Watch Ultra seems closer in places with some split times while we know from peering down at the Epix very early into the race that it was pretty much 0.5 miles out from the course markers.

Then it’s into those maps and this gives us a much clearer indication of how both the Ultra and the Epix performed. The Garmin clearly had its problems quite early into the course, but the Apple Watch Ultra wasn’t immune from some early issues as well. 

Chicago Marathon GPS tracks: Apple Watch Ultra (blue) and Garmin Epix 2 (red)

Later in the race around the 20km mark, the Garmin seems to suffer more routing issues and has us running through water, but the Ultra is not immune to delivering GPS tracks that dont match the route.

For most of the course, both the Ultra and Epix GPS tracks look okay, but we seem to encounter a few more issues with the GPS traces on the Epix based on our data.

Chicago Marathon GPS tracks: Apple Watch Ultra (red) and Garmin Epix 2 (blue)

While we wanted to focus mainly on GPS performance here, it’s worth mentioning that using the Watch Ultra in the more precise tracking mode saw a battery drop-off of around 20%, which interestingly was roughly the same level of drop-off experienced on the Garmin Epix in its top multiband mode as well.

Is the Apple Watch Ultra fit for a marathon?

Now obviously we were focusing mainly on the GPS performance and data like pacing and split times to find out if the Apple Watch Ultra would tell us an accurate picture of a race renowned for creating problems for watches tracking the course.

The Ultra does feel better suited to a marathon, simply for the performance of the battery alone, even with heart rate monitoring in use.

We’ve tested previous Apple Watches in the marathon scenario conditions, and the Ultra definitely fared better on that front from a battery and overall performance point of view.

When it came to putting that dual-frequency GPS mode to the test in truly testing conditions, we were actually surprised how well it performed.

It certainly wasn’t perfect, but compared to how it performed next to the Garmin Epix, which we’ve had a very good experience with in general, the Apple Watch Ultra performed far better. And that's a huge badge of honor for Apple.

If anything it shows that Apple has been on a journey to make its smartwatch feel like a true running companion. For a few years, the Apple Watch has been a solid running companion – and the Ultra has the credentials to take that even further.

The Ultra marks a significant moment in that journey. One that shows that when it comes to race day, the Apple Watch Ultra can go toe-to-toe with one of the best watches you can buy to track your runs right now – and deliver arguably a better experience.


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