Fitbit's AFib Detection Works Only on Certain Models

Fitbit can detect signs of atrial fibrillation (AFib), but only if you own one of the models equipped with an ECG app. The Fitbit Sense and Fitbit Sense 2 are the only consumer Fitbit watches that include this feature. If you have an older Fitbit model—even a newer one like the Charge 5—the ECG app is not available, and the device cannot perform AFib detection.

The ECG app works by recording your heart's electrical activity for 30 seconds while you hold your wrist still. After the recording, Fitbit analyzes the pattern and gives you one of four results: normal sinus rhythm, possible AFib, inconclusive, or unable to classify. This is not a diagnosis. The app is meant to flag patterns that a doctor should review, not to replace a medical evaluation.

Key Takeaways

  • Only Fitbit Sense and Fitbit Sense 2 have the ECG app needed to detect AFib patterns; other Fitbit models cannot perform this test.
  • The ECG app records 30 seconds of heart rhythm and flags possible AFib, but results are not a medical diagnosis and require doctor review.
  • All Fitbit models track resting heart rate and irregular rhythm notifications, which may alert you to changes worth discussing with your doctor.
  • A "possible AFib" result means you should contact your doctor, but many inconclusive results turn out to be normal when checked by medical equipment.
  • Fitbit's AFib detection is not a substitute for a medical-grade ECG, which your doctor can order if symptoms or Fitbit readings concern them.

How the ECG App Actually Works

To use the ECG app on a Fitbit Sense or Sense 2, open the app on your watch and place two fingers from your opposite hand on the metal contacts on the back of the watch. Keep your wrist still and your arm relaxed for the full 30 seconds. The watch records the electrical signal traveling through your heart and compares it to known patterns of normal rhythm and AFib.

The app then displays one of four possible results. A normal sinus rhythm result means your heart's electrical pattern looked regular during those 30 seconds. A possible AFib result means the pattern showed irregularities consistent with AFib, and you should tell your doctor about it. An inconclusive result means the recording was unclear—this happens often and does not mean something is wrong. An unable to classify result means the watch could not analyze the recording, usually because of movement or poor contact.

One important limitation: a single normal reading does not rule out AFib. AFib can be intermittent, meaning your heart rhythm may be normal at one moment and irregular hours or days later. This is why doctors often use longer monitoring devices like Holter monitors or event recorders when they suspect AFib.

What Fitbit Models Can and Cannot Do

Fitbit models without the ECG app still track your heart in other ways. All Fitbit watches and bands record your resting heart rate throughout the day and night. They also send you irregular rhythm notifications if the device detects an unusually fast or irregular heartbeat while you are at rest. These notifications are not AFib diagnoses—they flag patterns worth mentioning to your doctor, but they can be triggered by many conditions, including caffeine, stress, or normal variation.

The Charge 5, despite being a newer and more expensive model than some older Fitbits, does not include the ECG app. Fitbit has not announced plans to add it to other models. If AFib detection is important to you and you do not own a Sense or Sense 2, you would need to upgrade to one of those models.

Why a Fitbit Result Is Not a Medical Diagnosis

Fitbit's ECG app is not FDA-cleared as a diagnostic tool. The FDA has cleared some smartwatch ECG features for detecting AFib—notably Apple Watch—but Fitbit's app has not gone through that same review process. This means Fitbit itself does not claim the app can diagnose AFib, only that it can detect patterns worth discussing with a doctor.

In real-world use, many people receive "possible AFib" results from their Fitbit, only to have their doctor's medical-grade ECG show normal rhythm. This happens because a 30-second recording on a smartwatch is much shorter and less detailed than a clinical ECG, which records from 10 leads instead of one and runs for at least several minutes. Smartwatch readings are also more prone to interference from movement, skin contact, and other factors.

If your Fitbit shows a possible AFib result, the correct next step is to contact your doctor and describe what happened. Bring the Fitbit result with you if you have an appointment. Your doctor may order a proper ECG, a Holter monitor, or other tests depending on your symptoms and medical history.

Irregular Rhythm Notifications on All Fitbit Models

Even if you do not own a Sense or Sense 2, your Fitbit may alert you to irregular heartbeats. Most Fitbit models can send you a notification if the device detects an unusually fast resting heart rate or an irregular rhythm while you are sitting still. These notifications are based on your personal baseline—the app learns what your normal resting heart rate is and flags significant deviations.

These notifications are useful as a general awareness tool, but they are not AFib-specific. A fast or irregular rhythm can result from exercise, caffeine, stress, dehydration, illness, or many other causes. The notification is a reason to pay attention to how you feel and to mention it to your doctor if it happens often, but it is not evidence of AFib on its own.

When to See a Doctor About Heart Rhythm Changes

Contact your doctor if you notice any of the following: a Fitbit notification about irregular rhythm that repeats over several days, a "possible AFib" result from the ECG app, chest discomfort or pressure, shortness of breath, dizziness, or fainting. You do not need to rush to an emergency room for a single notification, but these are worth a phone call to your doctor's office.

If you have symptoms like chest pain, severe shortness of breath, or fainting, call 911 or go to an emergency room when ready. Do not wait for a Fitbit reading or a doctor's appointment in these cases.

Frequently Asked Questions

Can I use my Fitbit ECG result instead of going to the doctor?

No. A Fitbit ECG result is informational only and is not a medical diagnosis. If your Fitbit shows a possible AFib result, you should contact your doctor. Your doctor may order additional tests or monitoring to confirm what is happening with your heart rhythm.

What does an inconclusive ECG result mean?

An inconclusive result means the Fitbit could not clearly read your heart's electrical pattern during those 30 seconds. This usually happens because of movement, poor contact between your fingers and the watch, or natural variation in your heartbeat. You can try the recording again, but one inconclusive result is not concerning on its own.

Does Fitbit's irregular rhythm notification mean I have AFib?

No. An irregular rhythm notification means your Fitbit detected a heartbeat pattern that differs from your normal baseline. This can happen for many reasons—caffeine, stress, exercise, or normal variation—and does not indicate AFib. If notifications happen frequently or you have symptoms like chest discomfort, mention it to your doctor.

Can I get the ECG app on my Fitbit Charge 5?

No. The ECG app is available only on Fitbit Sense and Fitbit Sense 2. Fitbit has not released the app for other models, including the Charge 5. If you want ECG capability, you would need to switch to one of those two models.

Is Fitbit's AFib detection as accurate as a hospital ECG?

No. A hospital or clinical ECG uses 10 leads and records for several minutes, giving doctors much more detailed information than a 30-second single-lead recording from a smartwatch. Fitbit's app is useful for flagging patterns worth investigating, but it is not a substitute for medical-grade testing.