How do I track heart rate with my Fitbit device?

Fitbit devices have optical heart rate sensors that use rapidly flashing green LEDs to detect changes in blood volume in the capillaries of your wrist. Light-sensitive photodiodes measure these changes, and your device calculates your heart rate in beats per minute (bpm). The infrared light is used to detect when the device is worn to improve the accuracy of your heart rate readings.

Turn on heart rate tracking

Heart rate tracking is turned on by default. If you’ve turned it off, here’s how to turn it back on:

1. On your device, open the Settings app .
2. Tap Heart Rate to turn the setting on.

Important: Your device does not track your heart rate when you swim.

Fitbit’s heart rate tracking accuracy is affected by your personal physiology, device placement on your arm, and the activity you're doing.

For a more accurate heart rate reading:

• Wear your Fitbit device on top of your wrist, and make sure the back of the device is in contact with your skin.
• Wear your device a finger’s width above your wrist bone when you’re not exercising.

• Wear your device a bit tighter and higher during exercise for an improved fit. The band should be snug but not constricting (a tight band restricts blood flow, potentially affecting the heart rate signal). Many exercises such as bike riding or weight lifting cause you to bend your wrist frequently, which could interfere with the heart rate signal if the watch is lower on your wrist.

My heart rate is visible on my device, but not in the Fitbit app

If your heart rate is shown on your Fitbit device, but it’s missing in the Fitbit app, it's possible that your device is disconnected from the app. For assistance with syncing issues, refer to the troubleshooting instructions in Why won't my Fitbit device sync?

My heart rate readings are inconsistent between devices

Your Fitbit's heart rate readings might not always match those from other devices, like chest straps or other wrist trackers due to the differences in technologies.

Differences between heart rate readings on your device and on exercise equipment may also be due to wrist or hand position. Make sure the back of your device is in contact with your wrist and that your band is snug.

You might also notice variations between your heart rate reading on new Fitbit devices compared with your old ones due to changes in the heart rate sensor or algorithm.

• Air temperature, stress level, alcohol or caffeine intake, immune response to illness, and medication use can affect heart rate (source).
• Cold weather can hinder your device's ability to accurately measure your heart rate during exercise because it affects blood flow to the skin.
• Sudden movements during sleep, like waking up and getting out of bed, or a poor wrist placement affecting the signal, can lead to increased heart rate readings.

Review our tips on How do I improve the accuracy of a heart-rate reading?

For any concerns about your heart rate data, contact your physician.

Resting heart rate is the number of times your heart beats per minute when you’re still and well-rested. Typically, resting heart rate ranges from 60-100 bpm, but the rate can vary based on age and fitness level.

Why should I track resting heart rate in the Fitbit app

Resting heart rate can be an important indicator of your fitness level and overall cardiovascular health. In general, active people often have a lower resting heart rate because their heart muscle is in better condition and doesn’t need to work as hard to maintain a steady beat.

How is resting heart rate different from sleeping heart rate

Your sleeping heart rate is detected continuously throughout the night, and is often lower than your resting heart rate, which is estimated each day. Learn more about your sleep data and sleeping heart rate.

Several factors can affect resting heart rate. Stress, alcohol or caffeine intake, or fever usually raise resting heart rate, while regular exercise or meditation can lower it. Air temperature and certain medications can also affect resting heart rate.

Heart rate zones, which are percentages of your maximum heart rate, can help you determine the intensity of your workout or activity.

Fitbit personalizes your heart rate zones using your heart rate reserve. This is the difference between your maximum heart rate* and your resting heart rate.

Heart rate reserve is an indication of your overall cardiovascular fitness. While your maximum heart rate is generally determined by age, your resting heart rate can be lowered when you increase your fitness level. When you lower your resting heart rate, you can increase your heart rate reserve.

For example, if you're 45 years old and your resting heart rate is 74 bpm, here’s the math:

First, calculate your maximum heart rate and heart rate reserve.

Next, use your heart rate reserve to calculate your personalized heart rate zones.

To check your personalized heart rate zones on the Active Zone Minutes screen in the Fitbit app:

1. From the Today tab in the Fitbit app on your phone, tap Active Zone Min.
2. Swipe up. Your personalized zones are listed in the "Your heart rate zones" section.

_{*Occasionally during intense exercise, you might notice your heart rate go above your Fitbit-calculated maximum heart rate.}

Fitbit Charge 4, Charge 5, Charge 6, Inspire 2, Inspire 3, Sense series, Versa series, and Google Pixel Watch series

Personalized zones adjust as your fitness level or other factors change.

All other devices

Heart rate variability (HRV) is the variation in time between heartbeats. A heart rate of 60 beats per minute doesn't mean your heart beats exactly once every second. Your autonomic nervous system determines the timing of each heartbeat.

HRV varies from person to person. Studies show that people with a higher HRV have better cardiovascular fitness and might be more resilient to stress. Mindfulness, meditation, sleep, and physical activity can help improve your HRV. A significant drop in HRV may indicate that your body is experiencing illness, stress, or depression or anxiety.

Why should I track HRV?

Track your HRV in the Fitbit app to help you gauge your overall well-being. Trends in HRV data can help you be more aware of how stress and lifestyle choices, such as nutrition and exercise, can affect your body

How does my Fitbit device track HRV?

Fitbit uses the common formula called Root mean square of successive differences (RMSSD) to determine HRV from your recent heart-rate data. In the graph, your latest HRV measurement is from the longest sleep period over the past 24 hours. Only sleep periods greater than 3 hours are considered.

Wear your device for at least a full day, including to sleep at night. Then check your stats:

1. In the morning, open the Fitbit app. On the Today tab , tap Health Metrics . Your heart rate variability is listed as one of your metrics.
2. Tap Heart rate variability (HRV) to check your data in detail. These details include graphs of your data over the course of a week, month, or year.
3. For details, tap Learn More above the graph.

Several factors can affect HRV, including age, sex, sleep quality, stress, and lifestyle choices, such as nutrition and exercise.

Charge 5, Charge 6, Inspire 3, Sense, Sense 2, Versa 3, Versa 4, and Google Pixel Watch series notify you when your device detects that your heart rate is outside of your high or low thresholds while you appear to be inactive for at least 10 minutes.

1. From the Today tab in the Fitbit app on your phone, tap Devices your device.
2. Tap High & Low Heart Rate.
3. Turn High heart rate notification or Low heart rate notification on or off.

When your Fitbit device detects your heart rate goes above or below your personal heart rate threshold while you’re inactive, you receive a notification on your device. Tap Open, and then tap the notification in the Fitbit app to learn more about your data and complete a survey where you log any potential factors, medications, and symptoms. You can use the information you log in the survey to track your heart health trends and share it with your healthcare provider.

To start, your thresholds are based on your age and typical resting heart rate. To adjust your thresholds:

1. From the Today tab in the Fitbit app on your phone, tap Devices your device.
2. Tap High & Low Heart Rate.
3. Turn on Custom in the High heart rate or Low heart rate section.
4. Tap Threshold and choose a new threshold.

To use your default thresholds, turn off the custom threshold.