This is according to data extracted from the Apple Watch by Brad Larson (via PocketNow), a software engineer and founder of SonoPlot. He took the data and then compared it with a dedicated heartrate monitor in the form of the Mio Alpha, a device which supposedly is comparable to that of chest strap monitors, and as you can see in the graph above, the Apple Watch is almost on par with the Mio Alpha.
There are some instances in the graph in which the Apple Watch was a bit higher or lower than the Mio Alpha, but we reckon those tiny discrepancies can be largely ignored by most users, unless of course you are looking for the ultimate precision in which you might want to try something else. Larson’s findings are also in line with a Consumer Reports’ rating in which they found that the Apple Watch is the most reliable smartwatch available in the market at the moment.