Introduction

Apple claims the new Apple Watch Series 12 and Ultra 4 have the "most accurate heart rate in a wearable", but the company has historically struggled to keep pace with competitors like Garmin. After weeks of hands-on testing, the gap has narrowed considerably, though the final verdict remains nuanced.

What Happened

I tested the Apple Watch Series 12 alongside a Garmin Forerunner 570 and a medical-grade chest strap across treadmill runs, outdoor trails, rowing, and strength sessions. Both watches tracked heart rate in real time, with the chest strap serving as the reference standard for comparison.

Early results showed both devices performing well, but each had distinct quirks. The Garmin sometimes lagged at workout start, while the Apple Watch occasionally missed data points during rapid intensity shifts.

Why This Matters

Heart rate accuracy directly impacts training insights, calorie estimates, and recovery tracking for serious athletes and casual users alike. Apple's improved sensor marks a noticeable leap over Series 10 and 11, positioning the watch closer to dedicated sports watches than ever before.

However, even Apple's best still struggles with quick heart rate spikes and may omit data points it deems uncertain, leaving gaps in the graph. Garmin maintains an edge in consistency, but Apple no longer lags behind as a "C-tier" performer.

Key Takeaways

  • The Apple Watch Series 12 delivers a substantial accuracy improvement over previous generations, often tying Garmin's top sensor in real-world tests.
  • Both watches underperformed slightly at the start of intervals, but the Apple Watch avoided the lag issue that sometimes plagued Garmin.
  • Rapid heart rate changes and strength movements challenged both devices, with the Apple Watch sometimes overestimating and the Garmin reading low.
  • A chest strap remains the gold standard for optical sensor comparisons, but for wrist-based tracking, Apple has closed the gap considerably.
  • Whether Apple claims "most accurate" depends on how you define accuracy: data completeness vs. point-perfect precision.

Conclusion

Apple has finally built a heart rate sensor that can stand shoulder-to-shoulder with the best in the business, but calling it the definitive "best" depends on what you value more: consistent data capture or point-perfect accuracy. For most users, the Series 12 offers reliable heart rate tracking that rivals dedicated sports watches, making it a worthy upgrade for anyone prioritizing wrist-based monitoring.