Apple Watch scores as the most accurate pulse meter among wrist wearables in a study

The team there pitted the Apple Watch against popular competitors like the Fitbit Charge HR, Mio Alpha and Basis Peak (yep, the hot one), and all of those against the gold standard of an electrocardiogram machine, making the 50 or so test subjects walk, run, or simply rest.

It turned out that the Apple Watch was 90% accurate on average, while the other three lingered in the low 80s. The difference, however, stemmed not from the resting heart rate, but from the one measured during physical activity, where the Apple Watch was much more on point. Obviously, it pays off that Apple developed a proprietary system using two light guides that are compared by software to adjust for movements and vasculature changes.

source: Time