The Garmin Forerunner 965 and Apple Watch Ultra 2 are two of the best sports watches I have tested in the last couple of years, and as a keen runner both are laden with features that help me during training and on race day.
To test out their accuracy and usefulness for racing, I wore both to run the Battersea Park half marathon in London last weekend, where I clocked a PR of 1:09.46. I checked the GPS tracks of both watches after the race, as well as comparing their distance to the mile markers on the course during the event.
I also wore a Polar Verity Sense armband heart rate monitor, which I’ve found to be reliably accurate during my testing, so I could check the HR readings of the Apple Watch Ultra 2 and Garmin Forerunner 965. The Verity Sense was connected to a Coros Pace 3 watch that I had in my pocket, just to make it easier to get the HR data after the race for comparisons.
GPS Accuracy
The race involved running eight and three-quarter laps around the bottom half of a park. It was a crowded event which meant I had to run wide on every loop aside from the first one, and looped courses like this are always a challenge for GPS accuracy in my experience.
Both the Garmin Forerunner 965 and Apple Watch Ultra 2 ended up tracking longer than the official half marathon distance of 21.1km (13.11 miles), with the Apple Watch clocking 21.50km (13.35 miles) and the Garmin 21.23km (13.19 miles). I almost certainly ran further than the official distance given I had to weave around people and run wide on corners, but even so the Apple Watch’s reading seems a bit high to me.
Looking at the GPS trace of the event you can see the loops recorded show the Apple Watch taking wider turns on most corners than the Garmin, adding the extra distance. On some turns I’d say the Apple Watch looks better than the Garmin, judging by my memory of the way I ran the race, but on some it looks like it's giving me some extra distance.
Overall the Forerunner 965’s distance was a lot closer to the race distance on an officially measured course, and even with the fact I had to run wide a lot of the time, I think the Garmin was a little more accurate on this front.
HR Accuracy
The Apple Watch Ultra 2 had a bad day on the heart rate front, consistently reading much higher than the Polar armband, and also dropping out entirely for some stretches. In contrast the Garmin Forerunner 965’s readings lined up closely with the armband’s for the whole race, with my heart rate rising steadily as I got more and more tired.
As a result the Garmin’s average and max heart rate readings were a lot closer to the Polar Verity Sense’s, and if I was using HR to judge my effort in the race it would have been a lot more useful than the Apple Watch Ultra 2.
That said, outside of this race, I’d say the Apple Watch Ultra 2 is usually OK for heart rate, and recently produced an accurate graph for me during a 10K race.
Pacing
For this race I used the pacer mode on the Apple Watch Ultra 2, where you set a target pace or time goal and it then shows how far ahead or behind that goal you are throughout the race. On the Garmin Forerunner 965 I used lap pace and manually took a lap each time I went through the timing mats that marked the start/end of each lap of the park, which was roughly every 2.4km (1.5 miles).
The Apple Watch pacer mode is great and I’ve used it in the past when running a marathon when it was pretty much spot on and helped me hit my target. However, because the distance tracked by the watch ended up higher than the half marathon distance, it was generous throughout the race in saying how far ahead of my target I was.
I had to ignore the pacer mode in the main and instead use the Forerunner 965’s manual lap splits and check my overall time against the mile markers on the course — luckily the math for my goal of sub-1:10 is easy because it’s 5:20 per mile. Though the Forerunner 965 also ended up recording a longer distance, I was able to judge my pace using it on each lap and it was more useful than the Apple Watch Ultra 2 in this event.
Verdict
There was a clear winner for this race, with the Garmin Forerunner 965 being more accurate on heart rate and more useful on pacing because it had an overall distance closer to the official half marathon distance.
The Apple Watch Ultra 2 still was pretty good on distance given I did have to run wide, but the heart rate accuracy was off and the normally great pacer mode wouldn’t have helped me hit my goal if I’d relied on it entirely.
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