The ECG app on Apple Watch records a single-lead electrocardiogram in about 30 seconds, right from your wrist. It works on Apple Watch Series 4 or later and all Apple Watch Ultra models. Here’s how to set it up, take a reading, and understand what the results mean.
What You Need Before Starting
The ECG app requires an Apple Watch Series 4 or newer, or any Apple Watch Ultra. It is not available on Apple Watch SE or on watches set up through Apple Watch For Your Kids. Your iPhone and Apple Watch both need to be running the latest software versions.
You also need to be in a supported region. The feature is available in dozens of countries including the United States, Canada, the United Kingdom, Australia, Germany, France, Japan, Brazil, India, and many more. Apple maintains a full list on its watchOS feature availability page. If you don’t see the ECG app on your watch, your region may not be supported, or you may need to update your software.
One other requirement worth noting: the FDA clearance for the ECG app specifies it is not intended for people under 22 years old.
How to Set Up the ECG App
Open the Health app on your iPhone. You should see a prompt to set up the ECG feature. Follow the on-screen steps, which include entering your date of birth and confirming a few health details. Once setup is complete, the ECG app will appear on your Apple Watch automatically. If you don’t see a setup prompt, check that your devices are updated and that your region supports the feature.
Taking an ECG Reading
The process is simple, but your body position and the watch fit matter more than you might expect.
Open the ECG app on your Apple Watch. You’ll see a screen asking you to rest your finger on the Digital Crown (the round dial on the side of the watch). Don’t press it down. Just hold your fingertip gently against it. This completes an electrical circuit between the sensors on the back of the watch (touching your wrist) and the Digital Crown (touching your finger), allowing the watch to detect your heart’s electrical signals.
Stay still for 30 seconds. Keep your arms resting on a table or in your lap. The watch will show a real-time waveform as it records your heart rhythm, then display your result when the recording is finished.
Getting a Clean Recording
A “Poor Recording” result is frustrating but usually fixable. The most common cause is movement. Even small shifts of your wrist during the 30-second recording can throw off the signal. Sit down, relax your arms, and try again.
Watch fit is the second biggest factor. The back of the watch needs to be touching your skin consistently. Tighten the band so it’s snug but comfortable. A loose watch that slides around will produce unreliable readings.
Sweat and moisture can also interfere. If you’ve been exercising or it’s a warm day, take the watch off, dry your wrist, dry the finger you’ll place on the crown, and wipe down both the crown and the back of the watch before trying again.
Two less obvious causes: electrical interference from nearby plugged-in devices can disrupt the signal, so try moving away from chargers or desktop computers. And if your watch is set to the wrong wrist orientation, it can produce poor results. Check Settings > General > Orientation on your watch and confirm it matches the wrist you’re actually wearing it on.
Understanding Your Results
After each recording, the app classifies your heart rhythm into one of a few categories.
- Sinus Rhythm means your heart is beating in a normal, regular pattern. This is the result most people will see.
- Atrial Fibrillation (AFib) means the app detected an irregular rhythm consistent with AFib, a condition where the upper chambers of the heart beat out of sync with the lower chambers. AFib can increase the risk of stroke and other complications, so this result is worth bringing to a doctor.
- Inconclusive means the app couldn’t confidently classify the recording. This can happen if your heart rate is very high or very low, or if the recording quality wasn’t good enough. Try again in a few minutes under calmer conditions.
The watch is not a full diagnostic tool, but its accuracy is genuinely impressive. In Apple’s internal validation study of 588 subjects, the algorithm showed over 98% sensitivity and over 99% specificity for distinguishing between sinus rhythm and AFib. A separate real-world clinical study published through the American Heart Association compared Apple Watch readings to standard 12-lead hospital ECGs and found 93.5% sensitivity and 100% specificity for detecting AFib on the first measurement. Taking a second reading when the first was inconclusive pushed sensitivity to 94.6% with specificity still at 100%.
Those numbers mean the watch is very good at correctly identifying AFib when it’s present, and extremely unlikely to flag AFib when it isn’t there. That said, a single-lead wrist ECG captures far less information than a 12-lead hospital ECG. It can detect AFib reliably, but it won’t pick up every type of heart abnormality.
Sharing Results With Your Doctor
Every ECG you take is stored in the Health app on your iPhone, and you can export any recording as a PDF to share with a physician. The PDF includes the waveform tracing, your heart rate, and the classification result.
To export a recording, open the Health app on your iPhone. Tap “Show All Health Data,” then tap “Electrocardiograms (ECG).” Select the specific recording you want to share, then tap the Share button. From there you can send it as an email attachment, AirDrop it, print it, or save it to your files. Your doctor can review the waveform just as they would any other single-lead ECG strip.
If you’ve received an AFib result, exporting that specific recording before your appointment gives your doctor concrete data to work with rather than just a verbal description of what the watch showed.
What the ECG App Can and Cannot Do
The Apple Watch ECG is a screening tool, not a replacement for clinical evaluation. It’s designed to detect one specific condition (atrial fibrillation) and confirm normal sinus rhythm. It won’t detect heart attacks, blood clots, or other types of arrhythmia. A normal sinus rhythm result doesn’t mean nothing is wrong with your heart. It means your rhythm looked regular during that 30-second window.
Where the feature shines is in catching intermittent AFib. Many people with AFib only experience episodes occasionally, which means a routine office visit might miss it entirely. Having the ability to take an ECG the moment you feel your heart flutter or race, then hand that recording to a cardiologist, is genuinely useful. It turns a vague symptom into documented evidence.