ECG Apple Watch App 2
Adam Sinicki / Android Authority

The Apple Watch’s electrocardiogram feature (ECG) is an exciting addition to recent models. The Apple Watch ECG app can provide far more accurate heart rate readings than typical optical sensors and could even identify potential arrhythmias.

But just how accurate is the ECG on the Apple Watch? How do you access it? And what do you do with that information? Read on, and we’ll explore the answers.

What does ECG record?

An electrocardiogram measures electrical signals from the heart intending to identify signs of atrial fibrillation. This is an irregular heartbeat that can lead to stroke or heart disease.

Your heart is a muscle, just like your biceps or your hamstrings. Like those other muscles, the heart also requires an electrical impulse to trigger contractions. This way, it is possible for an ECG to measure the timing and strength of the heart rate, resulting in a far more accurate reading than would be possible with an optical monitor.

The Apple Watch ECG app looks for irregularities between the rhythms of the upper and lower chambers of the heart. These should ideally be in sync, which is referred to as a “sinus rhythm.”

Read more: What is ECG, and why does it matter?

apple watch series 6 review heart rate sensor
Jimmy Westenberg / Android Authority

Atrial fibrillation is a heart condition that can cause an irregular and possibly rapid heart rate. You may find that your resting heart rate is above 100 beats per minute. This can cause other symptoms such as dizziness, breathlessness, and tiredness. This, in turn, is caused by abnormal electrical impulses that lead to rapid contractions and prevent the heart from relaxing properly between beats.

There are also different types of atrial fibrillation:

  • Paroxysmal atrial fibrillation: Episodes that come and go
  • Persistent atrial fibrillation: Lasting for seven days or more
  • Long-standing persistent atrial fibrillation: Lasting for a year or longer
  • Permanent atrial fibrillation

This is where having a device that can potentially flag up these symptoms becomes useful. Seeing as atrial fibrillation can come and go, a doctor might fail to pick up symptoms during a visit. Using the Apple Watch ECG app, you can test yourself whenever you start to feel unwell.

The Apple Watch might also be able to identify other forms of tachycardia, such as atrial flutter. Atrial flutter is similar to atrial fibrillation but has a more organized/less chaotic waveform.

How does ECG on Apple Watch work?

ECG Sensor Apple Watch
Adam Sinicki / Android Authority

Thanks to the electrical heart rate monitor located around the back of the device and in the Digital Crown, the Apple Watch can provide an ECG “similar to a single-lead” ECG. This is as compared with the 12-lead ECG that doctors offer. The latter records signals from different angles across the heart to provide 12 separate waveforms.

It’s important not to mistake the Apple Watch for a medical device. The Apple Watch ECG app should not be used to diagnose any condition. Apple is very keen to point out that it can’t detect heart attacks, blood clots, or strokes. These cautions have not prevented many health experts from voicing their concerns over the feature, however. The issue is not the ECG app itself but rather the potential for users to place too much stock in their readings.

If you feel strange and you don’t see that reflected in the app, you should still get yourself checked by a doctor.

The best way to think of the Apple Watch ECG app is as a cue to go and see a doctor. If you feel strange and your watch corroborates your concerns, it’s worth getting yourself checked. With that said, if you feel strange and you don’t see that reflected in the app, you should still get yourself checked.

How to set up the ECG Apple Watch app

ECG Health App
Adam Sinicki / Android Authority

To start using ECG on Apple Watch, you first need to set it up in the Health app. This process will install the app on your device and provide it with the necessary permissions.

Open Health and scroll down on the “Summary” screen until you find the relevant widget. Click “Set Up ECG App.” Follow the on-screen steps. This includes adding your age. Unfortunately, the Apple Watch ECG app is not intended for those under the age of 22.

For some, the ECG widget might not be present on the Summary screen. You’ll need to scroll to the bottom and go to Heart > Electrocardiograms (ECG) > Set Up ECG App in those cases. Once you’ve gone through all the necessary steps, the Apple Watch ECG app will be installed and ready to use at any time.

Note that the feature is only available on Apple Watch Series 4 and above.

Related: Apple Watch Series 6 review: Take notes, Google

How to take an ECG reading on Apple Watch

ECG Apple Watch App
Adam Sinicki / Android Authority

Once everything is set up, you can take an ECG reading at any time by opening the app from your watch itself. Apple advises that you do this “any time you feel symptoms such as a rapid or skipped heartbeat.” In other words, if you feel strange, it’s worth giving it a go. This means that the ECG won’t be taking regular readings like the optical sensor, so you’ll need to actively take a reading when you want one.

Once the app has launched, you should rest the arm you wear your watch on a table or your own leg. Try to move as little as possible. Hold a finger from your other hand against the digital crown and wait until the app signals the process is finished. This should take 30 seconds.

The Apple Watch ECG app will show you the type of heart rhythm you have. You can also add symptoms below this if you should wish.

To see the actual heart rate chart that was plotted, alongside any previous recordings, open the Health app and go to Summary > Heart > Electrocardiogram (ECG).

See also: The best fitness trackers you can buy

Once you have taken your ECG, you will be given one of five outcomes:

  • Sinus rhythm: This is a healthy pattern between 50 and 100BPM and is considered normal.
  • Atrial fibrillation: This is an irregular and possibly high pattern.
  • Low or high heart rate: This is a heart rate under 50BPM or over 120BPM.
  • Inconclusive: This means the recording can’t be classified.
  • Poor recording: Unique to ECG version 2, this means the quality of the recording was not adequate to provide a classification.

Of course, the one to look out for is “atrial fibrillation.” If this is your outcome, assess how you are feeling, and consider booking a visit to your physician.

Keep in mind that many things can affect your heart rate, such as exercise, emotional stress, or alcohol consumption. If you have just done a workout, your heart rate may likely be high. The best time to take a reading is when you are otherwise calm.


The Apple Watch ECG app is a potentially useful and fascinating tool, as long as it is used appropriately and with an understanding of precisely what it is and isn’t capable of. Even just as a way to get a more accurate heart rate reading, the ECG app will be helpful for many.

Of course, the Apple Watch isn’t the only smartwatch with ECG capabilities. Others include the Samsung Galaxy Watch 3 and Watch Active 2, Fitbit Sense, and Withings ScanWatch.