The built-in heart rate monitor feature of Apple Watch is great for exercise and monitoring general heart health, but from time to time you may notice the heart rate number reported back seems unusual given your present state. For example, you may be sitting at your desk working and see some number way out of line with your regular heart rate, or perhaps you’re exercising and you see a number much below what you’d expect. These outlier readings happen somewhat frequently on Apple Watch, but there’s usually a reason that is easy to address.
Wait for a Second BPM Reading
First, if you’re seeing a reading that doesn’t look quite right, be sure to leave the Watch heart rate glance active for another few seconds so that another reading or several can be taken. The latter readings tend to be more accurate if the first one is way out there, for example I’ve had readings tell me my heart rate was 150 BPM while sitting at a desk (come on I didn’t drink THAT much coffee!) but after letting the Watch read heart rate a bit longer, it jumped back into a typically expected range. These outlier readings are fairly common, and perhaps a software update can address these.
OK, so you’ve let Apple Watch get another reading or four, and the heart rate is still way off? Why?
Be Sure the Apple Watch Band Has a Snug Fit
The most common cause of Apple Watch providing inaccurate heart rate readings appears to be due to the fit of the Watch band itself. A loosely fitting band that moves around at all, or that has notable gaps between the Watch and the skin, can easily cause an inaccurate reading. For the most accurate heart rate readings, you will want to be sure you’re wearing the Apple Watch fairly snug against your skin, which is a bit easier with the Apple Watch Sport bands and various bands with magnetic latches rather than some of the other bands, particularly the link bracelet. If you don’t have an Apple Watch Sport band, you can get a surprisingly good quality knock-off Apple Watch Sport band from Amazon for considerably cheaper than what you’d pay at Apple for an ‘official’ plastic band. Whatever band you use, just be sure it fits snug for the best results.
Check for Grime on Skin or Other Sensor Obstructions
Another frequent reason why Apple Watch may offer inaccurate readings is if the Apple Watch light sensors on the back of the device are obstructed, whether it’s grime, heavy dirt, film, undried lotions, or sunblock. From personal experience, certain brands (maybe types?) of sunblock can cause the Apple Watch heart rate reading to be way off, so if you exercise with the Apple Watch outdoors and wear sunblock, you’ll want to be mindful of that being a possible cause of an inaccurate hear rate reading. This seems to be particularly true with the greasier sunblock types that are sort of shiny on application, typically found with waterproof varieties, whereas the sunblock creams that dry out and don’t leave the skin all shiny usually are fine.
A Bug? A Software Solution?
As hinted at earlier, it’s also possible that some software issues may cause the Apple Watch heart rate monitor to be inaccurate, so be sure you install WatchOS updates when they’re available for Apple Watch to get any potential bug fixes or improvements to the devices capabilities. For example, a future Apple Watch update could discard the very first heart rate glance reading which is typically the inaccurate one, and only show the accurate BPM after that.
For what it’s worth, I’ve tried resetting and erasing the Apple Watch to set it up as new again, and it didn’t make a difference in the heart rate reading ability, so unless the feature isn’t working at all for you, that troubleshooting step is likely to be fruitless.
Have you found Apple Watch heart rate monitor to be accurate? Do you experience occasional inaccuracies? Let us know in the comments if you have any tricks or experience with the heart rate reading feature.