Gone are the days when you’d need to go to a doctor or use a sphygmomanometer to get an idea about your heart rate. In fact, more recent iterations of the Apple Watch, like the Series 7, are able to get you an accurate BP reading as well.
However, this begs the question, how accurate are the heart rate readings you get from an Apple Watch?
How Does An Apple Watch Measure Your Heart Rate?
Before we get into accuracy, understanding how the Apple Watch measures your heart rate can help you get an idea of the level of sophistication involved in the entire process. Ever noticed a green LED gleaming at the edge of your Watch? Well, that’s your device going to work!
In layman’s terms, an Apple Watch uses tiny green LEDs that house tiny diodes which are photosensitive. When your blood flows, these diodes are able to accurately predict the amount of blood flowing through your wrist.
With that said, there’s a difference between the amount of blood that flows compared to when your heart beats and when it doesn’t. So, by gauging the amount of light absorbed, an Apple Watch can predict the amount of time your heart takes to beat and provide a relatively accurate reading.
The Optical Sensor (Infrared)
Green LEDs are not all an Apple Watch uses. While considered relatively old, Infrared can still provide a highly accurate reading of your heart rate. Since the primary method consumes a lot of your battery, the Apple Watch’s infrared sensor is used to provide background heart rate information.
Here’s a quick look at when either of these sensors are used:
| Infrared Sensor | Optical Heart Sensor |
| Background Heart Rate Measurement | Heart Rate Variability (HRV) |
| Extra Calibrations | Workouts |
How Accurate Is The Apple Watch?
With all the technical jargon out of the way, how accurate is the Apple Watch in terms of measuring your heart rate? While we aren’t researchers by any means, we’ve done a few tests with the Apple Watch ourselves and have been pleasantly surprised by the results. Here’s a quick look:
| Device Used | Person 1 | Person 2 |
| Clinical Sphygmomanometer | 65 | 74 |
| Apple Watch Series SE | 64 | 76 |
| Variance | 1.55% | 2.6% |
Considering the fact that your heart rate can vary on its own, from our testing, the Apple Watch’s heart rate measurement is extremely accurate. However, it’s quite okay if you aren’t so sure of our tests.
Is The Apple Watch Clinically Accurate?
Thankfully, a medical report done by JMIR Mhealth also reaches the same conclusion. In essence, the Apple Watch was deemed as a clinically acceptable way to measure the heart rate of an individual who suffers from cardiovascular disease.
Why is that finding important? In essence, this signifies the fact that the Apple Watch can indeed be used for clinical measurements. For a device to be considered as clinically accurate, it needs to carry the same level of accuracy as that of a device that is already being used medically.
Therefore, the heart rate measurement on the Apple Watch is accurate and can be used to accurately determine one’s heart rate.
Can The Apple Watch’s Heart Rate Be Used For Diagnosis?
If the Apple Watch is clinically accurate, can it be used by a medical professional to check your heart rate? While it can be used to get a reading, it cannot be used to determine your exact heart rate due to a few reasons:
- Personalized Approach: Unlike a clinical device that can cater to multiple users, an Apple Watch, though, only retains information for a specific user.
- Not Always Viable: Having wet hands, damaged skin, or just a bad sensor can be one of the multitudes of reasons an Apple Watch just doesn’t give you an accurate reading.
- Detailed Statistics: The Health app, while intuitive, does not allow you to quickly export data or plot it in a way that helps doctors formulate an accurate result.
All in all, an Apple Watch remains a great device for tracking your health and fitness. While the heart rate measurement is extremely accurate and even clinically so, it does carry with it some caveats that may hinder its usage in a more professional setting.
I bought my first smartwatch in 2018 and have been wearing one ever since. It might get frustrating at times to receive 100 notifications a day. That's why we need to know how to make the best of them and how to use them to improve our daily lives, not the other way around. I write about the newest smartwatches, I create top picks, and I write helpful guides and simply explain complicated things.