I ran a marathon with the Apple Watch Ultra 4 and Coros Pace Pro 4 to test their accuracy and battery life — here’s the winner

In a recent test, the author compared the Apple Watch Ultra 4 and Coros Pace 4 Pro to evaluate their accuracy and battery life during a marathon. Both watches, released in September, impressed the author overall, with the author rating the Coros as one of the best sports watches and the Apple Watch Ultra 4 as their favorite sporty smartwatch. The author wore both watches during their final week of training and on race day, finishing the Frankfurt Marathon in 2:25.

For the test, the author focused on GPS and heart rate accuracy, battery life, and design differences. The Coros Pace 4 Pro was cheaper at $449 compared to the Apple Watch Ultra 4's $799 price tag. The Coros Pace 4 Pro featured a lightweight, slim design with a sapphire crystal case and a titanium bezel, while the Apple Watch Ultra 4 had a full titanium case, making it more robust and heavy.

In terms of GPS accuracy, the Coros Pace 4 Pro logged a distance of 42.52km (26.42 miles), while the Apple Watch Ultra 4 recorded 43.07km (26.76 miles). The official marathon distance is 42.19km (26.21 miles). The author found the Coros Pace 4 Pro to be more accurate, as it was closer to the kilometer markers on the course and they were able to stay close to the most direct racing line throughout the event. The Apple Watch Ultra 4's total distance appeared to be too long, even for the author.

The heart rate accuracy was not thoroughly evaluated due to the lack of a chest strap for comparison and the use of arm sleeves during the marathon that may have affected sensor accuracy.