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Feature availability depends on the watch model, iPhone, software version, country or region, age, pregnancy status, and health history. The information below reflects Apple’s documented features and requirements available through August 2026.
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Apple Watch heart-health features at a glance
| Feature | Automatic or manual? | What it does | Most important limitation |
|---|---|---|---|
| Heart-rate monitoring | Automatic | Estimates pulse rate using an optical sensor | A pulse reading is not an ECG or diagnosis |
| High/low heart-rate notifications | Automatic | Alerts when your rate stays above or below a selected threshold during inactivity | It does not identify the cause |
| Irregular Rhythm Notifications | Automatic | Periodically screens for a pulse pattern that may suggest AFib | It is not continuous monitoring or confirmation of AFib |
| ECG app | Manual | Records an approximately 30-second, single-lead ECG | It is not a 12-lead clinical ECG |
| AFib History | Automatic | Estimates weekly AFib burden for people already diagnosed with AFib | It is retrospective, not a live alert or exact measurement |
| Cardio Fitness | Automatic after qualifying workouts | Estimates VO₂ max from outdoor walking, running, and hiking | It is an estimate, not a laboratory test |
| Hypertension Notifications | Automatic screening | Looks for patterns associated with possible chronic high blood pressure | It does not measure blood pressure; a cuff is required for follow-up |
Resting heart rate, heart-rate variability, cardio recovery, workout zones, Vitals, Blood Oxygen, and sleep-apnea notifications are useful supporting or adjacent features, but they are not equivalent to a heart-disease detector.
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Heart-rate monitoring: the foundation
Apple Watch uses an optical heart sensor, commonly called PPG. It shines light into the skin and estimates pulse by detecting changes in blood volume as the heart beats. The watch collects readings periodically in the background and generally samples more frequently during workouts or other activity. Results are stored in the Health app, where trends are more useful than a single isolated number.
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![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.
The watch can provide current heart rate, resting heart rate, walking heart-rate average, workout heart rate, heart-rate zones, heart-rate variability, cardio recovery, and other related data. These are measurements or estimates of pulse behavior—not direct observations of every electrical event in the heart.
An optical pulse reading and an ECG are different. PPG measures the mechanical result of a heartbeat at the wrist; an ECG records electrical activity through electrodes.
Readings can be affected by movement, loose fit, cold skin, tattoos, moisture, exercise, stress, illness, dehydration, medication, and sensor limitations. Look for persistent trends and consider symptoms and clinical measurements rather than treating one unusual number as a diagnosis.
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Apple Watch can alert you when your heart rate remains above or below a threshold you choose while you have been inactive for at least 10 minutes. The threshold is configurable, so there is no single number that is appropriate for everyone.
How to enable them
- Open Settings on Apple Watch.
- Tap Heart.
- Tap High Heart Rate Notifications or Low Heart Rate Notifications.
- Select a threshold.
On iPhone, use Watch > My Watch > Heart > High Heart Rate or Low Heart Rate.
An alert means the watch observed a sustained rate outside your selected threshold during inactivity. It does not establish AFib or explain the cause. Exercise, stress, fever, alcohol, dehydration, medication, athletic conditioning, and conduction problems can all affect heart rate.
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![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.
Low Power Mode can disable background heart-rate measurements and heart-rate notifications, reducing the feature’s usefulness. A chest-pain, fainting, severe-shortness-of-breath, or other emergency situation should never be managed by waiting for a watch alert.
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Irregular Rhythm Notifications periodically analyze pulse data in the background and may notify you when the pattern appears consistent with AFib. The feature is a screening tool, not a continuous AFib monitor. It can miss episodes because checks are periodic and require usable sensor data.
How to set it up
- Open the Watch app on iPhone.
- Tap My Watch > Heart.
- Tap Set Up Irregular Rhythm Notifications in Health.
- In Health, tap Set Up and follow the instructions.
A notification may suggest AFib; it does not confirm it. Arrange medical follow-up, especially if you have symptoms. Apple’s heart-health guide explains the feature and its availability requirements.
ECG app: a manual rhythm check
The ECG app uses the electrical heart sensor to record a waveform similar to a single-lead Lead I ECG. It can classify that particular recording as sinus rhythm, AFib, high or low heart rate, or inconclusive. A clinical ECG normally uses 12 leads and views the heart from multiple angles.
The app is supported on Apple Watch Series 4 or later and all Apple Watch Ultra models. It is not supported on Apple Watch SE, and availability varies by country or region. Apple says it is not intended for people younger than 22.
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- Wear the watch snugly on the configured wrist.
- Open the ECG app.
- Rest your arm on a table or in your lap.
- Place a finger from your opposite hand on the Digital Crown without pressing it.
- Remain still for about 30 seconds.
- Review the result and optionally tap Add Symptoms.
What the results mean
- Sinus rhythm: The recording appears regular within the app’s stated range. It does not prove that your heart is healthy.
- AFib: The recording appears irregular in a way consistent with AFib. If you have not been diagnosed, contact a clinician.
- High or low heart rate: The rate is outside the app’s classification range.
- Inconclusive: The recording could not be classified reliably.
- Poor recording: Repeat with better fit, clean dry skin, and less movement.
Apple says ECG app version 1 assesses AFib between 50 and 120 BPM, while version 2 assesses it between 50 and 150 BPM. A rate outside the relevant range may not be classifiable for AFib.
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- 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.*
In a clinical trial of approximately 600 subjects, Apple reported 98.3% sensitivity for AFib and 99.6% specificity for sinus rhythm among classifiable recordings. Those figures do not guarantee the same result for every person or recording; real-world readings can be inconclusive or unclassifiable. See Apple’s ECG documentation.
The ECG app cannot detect a heart attack, blood clot, stroke, high blood pressure, congestive heart failure, high cholesterol, or every arrhythmia. If you think you may be having a heart attack, call emergency services immediately.
AFib History: retrospective burden for diagnosed AFib
AFib History uses optical-sensor pulse data to estimate the percentage of time your heart showed signs consistent with AFib while you wore the watch. It is intended for people who already have an AFib diagnosis, not as a general-purpose first diagnosis.
To set it up, open Health > Search > Heart, scroll to Get More From Your Health, tap Set Up under AFib History, and follow the instructions.
Apple says that after the watch has been worn at least five of seven days for 12 hours per day, you may receive a Monday notification with an estimate for the previous calendar week. The estimate depends on wear time, usable data, and the algorithm’s ability to recognize the pattern.
AFib History is different from Irregular Rhythm Notifications: the latter screens for possible AFib and sends alerts; AFib History estimates retrospective burden for someone already diagnosed. AFib burden is not the same as stroke risk, symptom severity, or a treatment recommendation. A clinician may instead prescribe an ambulatory ECG monitor when exact timing or rhythm confirmation is needed.
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![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.*
Cardio Fitness and VO₂ max
Cardio Fitness estimates VO₂ max—the maximum amount of oxygen your body can use during exercise—from selected outdoor walks, runs, and hikes. Indoor workouts do not count toward the estimate.
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Enable notifications through Watch > My Watch > Heart > Set Up Cardio Fitness Notifications in Health. Apple categorizes results by age and sex as Low, Below Average, Above Average, or High. A low result can trigger a notification, and another may arrive every four months if it remains low.
This is an endurance and population-health metric, not a diagnosis. Results can be affected by GPS quality, pace, terrain, workout type, sensor fit, age, sex, medication, and conditions that alter heart-rate response. Apple warns that some conditions or medications that limit heart rate can cause an overestimate. A formal exercise test is more appropriate when clinical assessment is needed.
Hypertension Notifications: screening, not blood-pressure monitoring
On supported models, Apple Watch analyzes optical heart-sensor data over 30-day evaluation periods and looks for patterns associated with possible chronic high blood pressure. It does not directly measure blood pressure.
Requirements
- Apple Watch Series 9 or later, or Apple Watch Ultra 2 or later
- iPhone 11 or later
- Supported current software
- Wrist Detection enabled
- Age 22 or older
- No previous hypertension diagnosis
- Not pregnant
- Availability in a supported country or region
Apple Watch SE is excluded.
How to enable it
- Open Health on iPhone.
- Tap your profile icon.
- Under Features, tap Health Checklist.
- Tap Hypertension Notifications.
- Confirm your age and diagnosis status, then complete the prompts.
If you receive a notification, Apple directs you to discuss it with a healthcare professional and use a third-party blood-pressure cuff. You generally record measurements twice daily for seven days in the Health app’s Blood Pressure Log. The watch’s notification is not a blood-pressure reading, does not diagnose hypertension, and is not intended to manage an existing diagnosis. It also does not detect heart attacks, stroke, blood clots, AFib, heart failure, or high cholesterol. See Apple’s Hypertension Notifications requirements and instructions.
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Supporting and related heart-health data
Resting heart rate
Resting heart rate can help reveal personal trends related to fitness, recovery, illness, stress, or medication. It is not diagnostic by itself.
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![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.
Heart-rate variability
HRV reflects variation between heartbeats. It varies substantially between people and is influenced by sleep, stress, illness, alcohol, training, and measurement conditions. A higher or lower result is not automatically better or worse.
Cardio recovery
Cardio recovery shows how heart rate changes after exercise. It can be useful as a trend, but readings depend on workout intensity, cooldown behavior, fitness, medication, and measurement timing.
Workout heart-rate zones
Heart-rate zones help manage exercise intensity. They are training tools, not heart-disease screening tools.
Vitals
The Vitals app combines overnight heart rate, respiratory rate, wrist temperature, Blood Oxygen where available, and sleep duration. After multiple nights, it establishes personal typical ranges and may notify you when multiple metrics fall outside them. Vitals provides context; it does not diagnose a cardiovascular condition.
Sleep-apnea notifications
Sleep-apnea notifications use overnight breathing-disturbance data. Apple describes possible notifications when data shows consistent signs of moderate-to-severe sleep apnea over a 30-day period. The feature is available on Series 9 or later and Ultra 2 or later for eligible users aged 18 or older without a previous sleep-apnea diagnosis. It is relevant to cardiovascular risk but does not measure blood pressure or diagnose a heart rhythm.
Blood Oxygen
Blood Oxygen is a general wellness and respiratory metric rather than a core heart-health diagnostic. Availability depends on model, region, and purchase details. In the U.S., Apple says some models purchased on or after January 18, 2024, with part numbers ending in LW/A, do not provide Blood Oxygen in Vitals.
Which Apple Watch supports which feature?
| Feature | Relevant support | Key caveat |
|---|---|---|
| Heart-rate measurements | Broad Apple Watch support | Optical readings can be affected by fit and conditions |
| High/low alerts | Models with supported heart-rate monitoring | Requires inactivity; Low Power Mode can disable them |
| Irregular Rhythm Notifications | Supported models, software, and regions | Periodic screening, not continuous monitoring |
| ECG | Series 4 or later and all Ultra models | Not available on SE; regional restrictions apply |
| AFib History | Supported models, software, and regions | For users already diagnosed with AFib |
| Cardio Fitness | Supported watches with qualifying outdoor workouts | Estimated VO₂ max |
| Hypertension Notifications | Series 9 or later; Ultra 2 or later | Not on SE; requires eligibility and cuff follow-up |
| Sleep-apnea notifications | Series 9 or later; Ultra 2 or later | Adjacent sleep feature, not a heart test |
Apple’s current-generation watchOS materials identify Series 11, Ultra 3, and SE 3 as current products, but a newer model does not automatically mean every health feature is available. The SE remains the major omission for ECG and hypertension notifications. Confirm the exact regional model and software support before buying.
Which model is right for heart features?
- Basic monitoring: A supported Apple Watch with optical heart-rate tracking covers passive trends, high/low alerts, workouts, cardio fitness, and—where supported—Vitals.
- ECG: Choose a Series 4-or-later or Ultra model that supports ECG in your country. Do not choose SE if ECG is essential.
- Possible hypertension screening: Choose Series 9 or later or Ultra 2 or later, and remember that you still need a validated upper-arm cuff for confirmation.
- Diagnosed AFib: AFib History may help track retrospective trends, but clinical monitoring can be more appropriate when exact episodes or rhythm confirmation matter.
Ultra models offer larger, more rugged hardware and longer battery life, but they are excessive if your only goal is ECG and heart-rate alerts. Apple’s official watch page is at apple.com/watch.
What to do after an alert or unusual reading
- Read the exact alert and note when it occurred.
- Check whether the band was snug, the skin was dry, and you were still.
- Repeat an ECG if the recording was poor or inconclusive.
- Record symptoms, activity, illness, medication, caffeine, alcohol, and other relevant circumstances.
- Contact a clinician for persistent or concerning results, an AFib notification, or a hypertension notification.
- Call emergency services immediately for chest pain or pressure, fainting, severe shortness of breath, sudden weakness, confusion, or suspected heart attack or stroke.
Do not use a normal watch reading to rule out an emergency. Apple Watch can miss events, and a normal result does not prove that you are healthy.
