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Check compatibility and regional availability before resetting anything. ECG works on Apple Watch Series 4 or later (except Apple Watch SE) and every Apple Watch Ultra model, paired with an iPhone XS or later, where the feature is approved. If you have chest pain, pressure, severe shortness of breath, fainting, or other possible heart-attack symptoms, call emergency services instead of troubleshooting: Apple Watch ECG cannot detect a heart attack.
For a supported watch, the usual causes are incomplete setup, outdated software, moisture, poor skin contact, movement, or electrical interference. Work through the checks below in order.
1. Confirm that your watch and iPhone support ECG
| Apple Watch model | ECG support |
|---|---|
| Series 4 and later, excluding SE | Yes, where available |
| Apple Watch Ultra models | Yes, where available |
| Apple Watch SE | No |
| Series 1–3 | No |
The paired iPhone must be an iPhone XS or later. Apple also says ECG is not intended for people under 22. See Apple’s current requirements at Apple Support and the Apple Watch User Guide.
An Apple Watch SE cannot gain ECG through an update, cleaning, a reset, or a third-party app. Imported, refurbished, or repaired watches should also be checked by exact model and service history.
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#1 Best Overall
![Apple Watch Series 11 [GPS 46mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - M/L. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/416RQ0rtsUL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
2. Check country or region availability
ECG is a regulated medical feature and is not offered in every country or region. Apple’s availability table lists supported locations and can change as approvals change: watchOS feature availability.
Moving countries, buying a watch abroad, or changing the Apple Account, iPhone, or watch region can produce a mismatch. Do not assume changing the iPhone’s region will unlock ECG; it is not a guaranteed or supported workaround. If ECG worked before a move or region change, verify the current availability listing and the feature version shown in Settings → Heart → ECG on the watch or Health → Search → Heart → ECG → About on the iPhone. Apple explains regional feature versions at Apple Support.
Rank #2
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Rose Gold Aluminum Case with Light Blush Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31caPPnRysL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
3. Set up or reinstall the ECG app
- On the iPhone, open Health.
- Tap Search, then Heart.
- Choose Electrocardiograms (ECG) and tap Set Up ECG App.
- Complete the on-screen health information and age confirmation.
- Open ECG on the watch and follow the instructions.
If the ECG section exists in Health but the watch app is missing, open Watch → My Watch → Heart. Tap Install in the ECG section if Apple provides that option. No ECG section at all usually points to an unsupported model, unavailable region, incomplete eligibility flow, or software problem.
4. Take the recording correctly
The watch back and Digital Crown form an electrical circuit through your body. Opening the app is not enough; your opposite hand must complete the circuit.
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Rank #3
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Starlight Aluminum Case with Starlight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31YiTby0pOL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
- Wear the watch snugly on the wrist selected in Watch → General → Watch Orientation.
- Make sure the watch back, wrist, and touching finger are clean and completely dry.
- Open the ECG app and sit down.
- Rest your arm on a table or in your lap.
- Touch the Digital Crown with a finger from the opposite hand. Do not press or turn it.
- Remain still, do not talk or type, and keep contact for the full 30 seconds.
- Tap Done; add symptoms if you wish.
ECG is designed for use between 32°F and 95°F (0°C and 35°C). Extreme temperatures, a loose fit, a watch worn on the opposite wrist from the orientation setting, or an accessory that interferes with crown contact can prevent a usable signal. The procedure is described in Apple’s ECG instructions.
5. Fix “Poor Recording” or “Inconclusive”
Dry every contact point
Retry only after swimming, showering, handwashing, or heavy sweating has fully dried. Dry the wrist, finger, watch back, and crown. Apple notes that complete drying after water or sweat can take an hour or more.
Rank #4
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Midnight Aluminum Case with Midnight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31Gq8SToFJL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
Improve contact and stability
- Fasten the watch securely without making it uncomfortably tight.
- Keep the back flat against bare skin.
- Use the opposite hand and keep the finger on the crown throughout.
- Remove unusual cases or accessories if they obstruct the crown or change the fit.
Eliminate movement and interference
- Sit with both arms supported.
- Do not walk, talk, flex the wrist, or type.
- Move away from plugged-in electrical devices, power adapters, and questionable chargers.
Poor recording means the signal quality was inadequate. Inconclusive means the strip could not be classified, often because of signal quality, movement, heart rate, or another limitation. A small percentage of people may naturally produce a weaker signal because of physiological differences, including heart position; repeated failures do not automatically prove the watch is defective.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.6. If ECG worked before but stopped
- Confirm the watch is still a supported model and that ECG is available in your current region.
- Install all available iOS and watchOS updates.
- Restart both the iPhone and Apple Watch.
- Check Watch → General → Watch Orientation.
- Clean and dry the watch, crown, finger, and wrist, then retry away from plugged-in electronics.
- Under Watch → My Watch → Heart, reinstall ECG if an Install button appears.
- Check the ECG feature version in Settings → Heart → ECG on the watch and Health → Search → Heart → ECG → About on the iPhone.
Unpairing and pairing again is a disruptive last software step. It may require restoring a backup and cannot fix unsupported hardware, regional restrictions, poor contact, or physical damage. If failure began after an impact, liquid exposure, repair, or a Digital Crown or sensor problem, contact Apple Watch service rather than repeatedly resetting it.
Best Value
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/41s72HIk5TL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
7. Understand the result
| Result | What it means |
|---|---|
| Sinus rhythm | The recorded strip did not meet the app’s criteria for atrial fibrillation. |
| AFib | The app detected a pattern that may be consistent with atrial fibrillation; it is not a definitive diagnosis. |
| Inconclusive | The recording could not be classified. |
| Poor recording | Signal quality was insufficient for classification. |
These labels apply only to that strip. ECG cannot detect a heart attack, stroke, blood clot, high blood pressure, heart failure, or every arrhythmia, and it is not a substitute for a clinical 12-lead ECG. Apple reports 98.3% sensitivity for AFib classification and 99.6% specificity for sinus-rhythm classification in classifiable recordings from a controlled study of approximately 600 subjects; those figures do not describe every real-world recording. See Apple’s limitations and validation information.
8. Find and share an ECG
- Open Health on the iPhone.
- Tap Search → Heart → Electrocardiograms (ECG).
- Select the recording.
- Use the share or export option to create a PDF for a clinician.
Share the strip with a healthcare professional when appropriate rather than treating it as a diagnosis. If readings repeatedly conflict with symptoms, arrange a clinical evaluation.
9. When to stop troubleshooting
Call emergency services for chest pain, pressure or tightness, severe shortness of breath, fainting or near-fainting, new severe weakness, confusion, or symptoms that feel like a heart attack. Do not wait for an ECG result; Apple specifically warns that the app cannot detect a heart attack.
For a compatible watch that still fails after correct setup, updates, restart, dry contact, proper technique, and interference checks, Apple service is appropriate—especially after impact, liquid exposure, visible damage, or failure of other sensors. Repair eligibility and cost depend on model, damage, warranty, AppleCare coverage, and region. A replacement may make sense for an unsupported SE or Series 1–3, but buying a new watch is unnecessary when the existing one is compatible and the cause is setup, moisture, software, or technique.
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