Smartwatch Heart Rate Accuracy: Ultra 4 vs. Fenix 9 Pro

Recent tests comparing the Apple Watch Ultra 4 and the Garmin Fenix 9 Pro reveal exceptional accuracy in heart rate monitoring for both high-end smartwatches. During a challenging 30-minute hilly run, both devices were worn alongside a chest-mounted electrical heart rate monitor, the Frontier X2, acting as a benchmark.

The results showed remarkable consistency, with the Garmin Fenix 9 Pro measuring an average of 159 bpm, the Apple Watch Ultra 4 at 160 bpm, and the Frontier X2 at 158 bpm. This narrow margin of just 2 bpm between all three devices indicates a high level of reliability for tracking during exercise.

Beyond heart rate, other metrics like calorie estimates were also comparable, with both watches estimating burns in the high 300s. While the watches' calorie counts were deemed more reliable due to broader data collection than the Frontier X2's estimate, the primary focus remained on heart rate accuracy.

When choosing between the two, user needs dictate preference. The Apple Watch Ultra 4 excels in its software, third-party app ecosystem, and overall smartwatch functionality. Conversely, the Garmin Fenix 9 Pro stands out with its extended battery life, lasting up to 10 days compared to the Apple Watch's 48 hours, and includes useful survival tools like an LED flashlight. For daily use and shorter activities, the Apple Watch may be preferred, while multi-day adventurers might favor the Garmin's durability and battery.