Skip to main content

Just how accurate is the Apple Watch heart rate monitor? It’s on par with an EKG

Apple Watch back charger
Bill Roberson/Digital Trends
Most fitness trackers aren’t terribly accurate, and heart rate monitors are even more fickle. And some smartwatches give back absurd numbers that belong to corpses or heart attack victims. Apple seems to have figured out a way to make the Apple Watch incredibly accurate, though. One user compared it to a heart rate monitoring strap that’s on par with EKG accuracy ratings, with the Apple Watch returning almost the exact same readings.

Engineer Brad Larson strapped on his Mio Alpha heart rate monitor, one of the most accurate monitors around, to compare its data to the Apple Watch’s results during a run. He posted the graph on Twitter, and the Apple Watch matches the Mio Alpha at nearly every data point. The two line graphs are almost perfectly synced, with only a few variations.

Seeing as the Mio Alpha is rated at EKG level standards of accuracy, the fact that the Apple Watch manages to match it so closely is very impressive. Most wearables return results that are very far off from heart rate monitoring chest straps, which are typically considered the most accurate. In our review of the Fitbit Charge HR, we found it to be 20 to 30 beats per minute higher than the chest strap rates during exercise, and between 5 to 15 beats higher during regular walking. That’s also been the case with smartwatches like the LG G Watch R, which took a few weeks to get close to accurate results.

Of course, the Apple Watch’s heart rate monitor has had its own issues, mainly when it’s been worn by people with dark tattoos on their wrists. The watch uses photoplethysmography technology, which uses green LED lights and light‑sensitive photodiodes to detect the amount of blood flowing through your wrist.

Normally, this tech works very well, as evidenced by Larson’s results, but dark tattoos absorb the light, interfering with the reading. There must be at least a few wrist-tattooed Apple Watch owners today who wish they had listened to their mothers.

Editors' Recommendations

Malarie Gokey
Former Digital Trends Contributor
As DT's Mobile Editor, Malarie runs the Mobile and Wearables sections, which cover smartphones, tablets, smartwatches, and…
We asked the experts if biological sex affects heart rate sensor accuracy
The Apple Watch Ultra's heart rate sensor active.

We already know that skin tone can affect the accuracy of a heart rate sensor on a smartwatch or fitness band, but what other factors can influence the results you get? For example, does biological sex make a difference?

To find out if heart rate sensor accuracy changed, we asked the experts. Here's what they told us.
Why ask the question?

Read more
Why this new Apple Watch Ultra app made me want to go diving
The Apple Watch Ultra and Oceanic+ app.

The Apple Watch Ultra is an adventure smartwatch, with special features aimed at hikers, trekkers, outdoors enthusiasts, and divers. Apple collaborated with Huish Outdoors to create the newly released Oceanic+ app, which in combination with the sensors on the Apple Watch Ultra, turns it into a fully functioning, certified dive computer.

Before starting this article, I set out to take an in-depth look at the Oceanic+ app, and at the same time, compare its functionality and usefulness with the G-Shock GWF-D1000 Frogman dive watch — which also has a dive computer. It was by doing this that the Apple Watch Ultra, once again, surprised me. It did so because it encouraged me to do something new, and the Frogman has never quite managed the same thing. What do I mean? Let me explain.
What do they cost and what about certification?

Read more
What is the newest Apple Watch?
Apple Watch Series 6 and Apple Watch SE side-by-side.

2022 is the year of the Apple Watch Series 8, the latest in Apple's celebrated line of smartwatches. While this year's model continues with much the same design as 2021's Apple Watch Series 7, it introduces new safety features, a temperature sensor, and the all-improved watchOS 9. Not only that, but the eighth entry in the Apple Watch series also brings a new premium model, the Apple Watch Ultra. It takes everything that makes the Apple Watch 8 great and amplifies it, featuring bigger dimensions, rugged (yet elegant) titanium casing, and an exclusive Wayfinder watch face (which is aimed at hikers).

The Apple Watch 8 and Apple Watch Ultra are the two newest Apple smartwatches available today, yet September of this year also brought the Apple Watch SE 2, equipped with similarly great battery life, faultless software, and highly comprehensive fitness tracking. This article offers a roundup of these three new models while also providing an overview of earlier Apple Watches no longer sold directly by Apple.
What is the newest Apple Watch?
The Apple Watch Ultra -- officially launched on September 23, 2022 -- is the newest and most state-of-the-art Apple smartwatch available today, closely followed by the Apple Watch Series 8 and Apple Watch SE (2022), both of which were released on September 16, 2022. These models usurped the Apple Watch Series 7 and Apple Watch SE (2020), respectively, with these two models discontinued by Apple.
Apple Watch models currently sold by Apple
Apple Watch Series 8

Read more