Pixel Watch 5 vs Apple Watch Ultra 3 and Garmin Fenix 8 Pro: marathon GPS test

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Tech companies always love to make big claims. Like the one Google made about the Pixel Watch 5: promised health, wellness and Wear OS improvements aside, there was one feature that my ears pricked up for. Google stated that the Pixel Watch 5 included its most accurate GPS route tracking for exercise. More interestingly, Google said that tracking outperformed the Apple Watch Ultra 3 and the Garmin Fenix 8 Pro .

I’ve used both of those smartwatches and I can confidently say they are two of the best performing smartwatches available for GPS route tracking. I’ve listened to other smartwatch brands talk big about Apple and Garmin-beating performance. Did I really believe Google was going to deliver? I was sceptical, given my experience of the GPS tracking on previous Pixel Watches.

But I still had my Fenix 8 Pro and Watch Ultra 3, which made for the perfect opportunity to see these promised performance gains for myself. Having just recently made it through the millions in the ballot to secure a spot in the double-day 2027 London Marathon, my mind immediately went to the part of the marathon route I know causes major issues with GPS.

I grabbed my watches, jumped on a train, and then onto the DLR tram service to the Isle of Dogs, where the nearby tall skyscrapers always create difficult GPS conditions. I ran miles 18-20 of the London Marathon course, and then did it in reverse, to put the Pixel Watch 5’s big GPS claims to the test.

(Image credit: Future / Mike Sawh) How exactly does the Google Pixel Watch 5’s new GPS work?

Before getting into how the testing went, it’s worth drilling down into just how Google says its GPS tracking outperforms the competition. Like the Fenix 8 Pro and Watch Ultra 3, the Pixel Watch 5 includes dual-band GPS. This means it can communicate to major satellites responsible for calculating our precise locations over two frequency bands. This can help to boost tracking accuracy when moving through tall buildings, densely forested environments and even during adverse weather conditions.

Dual band GPS setups have started to appear across a range of smartwatches and in my own testing, dual band-packing watches from Apple, Garmin and Suunto have delivered the strongest performance.

Along with the latest in GPS technology in tow, Google says it uses data it has already captured of buildings in Google Maps alongside AI to better account for the areas where GPS signals bounce off buildings. It also used GPS reference stations it has positioned around the world to help deal with the impact that atmospheric conditions can have on GPS tracking.

If you’ve used a smartwatch with GPS, then you’ll know it’s a feature that does have a notable impact on battery drain. This is something Google had to think about here. Google has made the decision to compress the raw GPS data captured on the watch and then send it to a server where it’s processed and corrected, then synced to the Google Health app. So the processing mainly take place off the watch or after your run, ride or hike.

How I tested

The challenger: Google Pixel Watch 5 Future / Mike Sawh The defending champs: Garmin Fenix 8 Pro and Apple Watch Ultra 3 Future / Mike Sawh I decided I’d do two runs. The first would be starting from mile 18 up to mile 20 on the London Marathon course and go a little further to run 5k. I’d then stop the watches and do the route in reverse.

I had a trimmed down version of the marathon route uploaded to my Garmin Fenix 8 Pro as it was the easiest watch to do it on. I also decided that I would wear the Pixel Watch 5 on one wrist and then swap over to the other for the second run, while having the Apple Watch Ultra 3 and Fenix 8 Pro sat on the opposite wrist. I had to make sure that the two smartwatches weren’t sitting too close together to prevent any accidental button presses that might impact on capturing the correct distance.

It’s also worth adding that I decided to use native workout tracking apps on all three watches to record runs.

The results

(Image credit: Future / Mike Sawh) On the first run, I had the Pixel Watch 5 on my right wrist with the Apple Watch Ultra 3 and the Garmin Fenix 8 Pro on the left wrist. I uploaded the routes to the very handy comparison tool IloveGPX . Before that though, I had to convert the route file captured by the Pixel Watch 5 from a TCX file to a GPX one. Thankfully it was quite easy.

Even before I began zooming into the GPS tracks I could already see some red squiggles, which belonged to the Garmin Fenix 8 Pro. On closer inspection, all three watches were pretty close to each other before the Fenix 8 Pro track started to noticeably drift off. Google and Apple’s tracks for the majority of the run remain close together.

I actually went a little off-route and ran longer than planned as some parts of the route were partly closed off. That meant an extra loop or two of that problematic GPS signal spot.

Moving onto Trafalgar Way, having passed Billingsgate Market and towards that final mile, and the three tracks come back together. There’s still time for Garmin’s track to veer slightly off course though, as I made my way to the end of the route in Poplar.

Looking at the distance tracked, I ended up running longer than the planned 5k route, and the Apple Watch Ultra 3 and Google Pixel Watch 5 recorded similar distance data — with the Fenix 8 Pro measuring longer with a difference of 0.2 miles/0.3km.

The average speed of the run was again similar on the Watch Ultra 3 and Pixel Watch 5, with the Garmin reporting a slower average speed.

On the second run, I switched the Pixel Watch 5 over to my left wrist and moved the Fenix and Apple Watch over to the right. I ran this run a little quicker than the first. At the beginning of the run, all three tracks remained together. Then as I started to approach those towering buildings around Canary Wharf once again, the Apple and Garmin tracks started to lose their way. Meanwhile, the Pixel Watch 5’s tracks manage to stick closest to the actual route I’d run. It’s not immune to issues, however, especially when I hit around Heron Quays and Bank Street Canary Wharf.

Looking over the distance tracked again and the three smartwatches post three different records. The Garmin again tracks longer, with the Apple Watch Ultra 3 being closest to the planned 5k route. It’s the Garmin that has me running a quicker-than-average pace throughout the run.

GPS tracks are only one part of the story

For anyone that’s run the London Marathon (or any race for that matter), it’s not just about distance covered. Pacing matters. Especially if you’re been training to chase down a particular finish time.

Bad GPS route tracking data can impact on pace data. Having run the London Marathon before, those GPS problems will cause your locating tracking to skip, suggesting you’re clocking off those miles quicker than you’re actually travelling.

That’s also why I paid attention to my current and average pace data on the three watches, as well as looking at how that pacing was broken down post-run.

During the run, the pacing fluctuated across all three watches. I found the Pixel Watch 5 had a tendency to struggle getting pacing data right at the beginning of the two runs before settling down after. It was a similar story for Apple and Garmin as well. They all seemed to struggle in the section of the route I’d expected them to.

Looking at the post-run data in the respective companion apps, the Pixel Watch 5 did indicate some quicker paces that I’d felt I’d run as well.

Are Google’s claims about the Pixel Watch 5’s GPS justified ?

(Image credit: Getty Images) I’m not going to say the Pixel Watch 5 is definitively a GPS great after two relatively short runs in albeit very challenging GPS conditions. What I will say is that I was pretty surprised by the results. I had fully expected the Pixel Watch 5 to flounder, but it was actually the most reliable in plotting my actual running route. The Apple Watch Ultra 3 also did well, while the Fenix 8 Pro had some wild moments in the produced GPS tracks.

I think if you’re mainly interested in having a record of your precise route, then this innovation is going to impress. I’d say hikers will certainly like the idea of it.

From a running perspective, specifically from a racing point of view, I’d also want accurate pacing to go with that strong route tracking in real-time too. I’m not wholly convinced the pacing data is as spotless as the route tracking seems to be. Maybe that’s something Google will look at for the next watch or even tighten up with a software update.

The Pixel Watch 5’s new GPS signals an important breakthrough for how smartwatches can deliver more accurate route tracking. Google’s access to an abundance of positioning data, along with the improvements it’s making with AI clearly play their part in making this type of leap in smartwatch GPS technology.

It’s definitely given me food for thought as I choose which smartwatch I step on that London start line with next April, that’s for sure.