Monitor your heart rate with Apple Watch
Learn how Apple Watch measures your heart rate, and get tips for a more accurate reading.
Check your heart rate
You can check your heart rate any time using the Heart Rate app. Open the app, then wait for Apple Watch to measure your heart rate. You can also view your resting, walking, workout, and post-workout heart rate.
You can also turn on heart rate notifications, so you know if your heart rate remains above or below a chosen beats per minute (BPM), or to occasionally check for an irregular heart rhythm.
Irregular rhythm notifications are available only with watchOS 5.1.2 or later. To enable irregular rhythm notifications, the notifications must be available in your country or region. Learn where irregular rhythm notifications are available.
View your recovery heart rate variability (Recovery HRV)
If you have Apple Watch Series 12 or Apple Watch Ultra 4, you can view your Recovery HRV. Your Recovery HRV measures how time varies between heartbeats, and can be an indicator of stress and recovery. HRV is sampled while you're still, so the number of measurements you see will vary according to your activity level.
On your Apple Watch, open the Heart Rate app.
Turn the Digital Crown to view your Recovery HRV.
Tap info
to learn more.
How Apple Watch measures your heart rate
The optical heart sensor in Apple Watch uses what is known as photoplethysmography. This technology, while difficult to pronounce, is based on a very simple fact: Blood is red because it reflects red light and absorbs green light.
Apple Watch uses green LED lights paired with light‑sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. When your heart beats, the blood flow in your wrist — and the green light absorption — is greater. Between beats, it’s less. By flashing its LED lights hundreds of times per second, Apple Watch can calculate the number of times the heart beats each minute — your heart rate.
The optical heart sensor supports a range of 30–210 beats per minute, and is designed to compensate for low signal levels by increasing both LED brightness and sampling rate.
The optical heart sensor can also use infrared light. The color of LED that your watch uses for sampling is determined by several factors, such as your watch model, your activity level, and whether you're sleeping.
Apple Watch Series 12 and Apple Watch Ultra 4 use green LEDs continuously during the day to provide a measurement as often as every five seconds, even when you're in motion. Infrared LED lights are used during your sleep schedule or if you've manually turned on a sleep focus. You can turn off continuous measurements with green LED lights:
On your Apple Watch, open the Settings app.
Tap Heart.
Turn off Continuous Measurements.
Apple Watch Series 4 and later and all models of Apple Watch Ultra also have built-in electrodes in the Digital Crown and the back of Apple Watch, which can measure the electrical signals across your heart when used with the Heart Rate app or the ECG app. When you place your finger on the Digital Crown, it creates a closed circuit between your heart and both arms, capturing the electrical impulses across your chest.
To use the electrical heart sensor to measure your heart rate, open the Heart Rate app and place your finger on the Digital Crown. You will get a faster reading with higher fidelity — getting a measurement every second instead of every 5 seconds. You’ll see "ECG" in Heart Rate Context when looking at recorded data for Heart Rate in the Health app. You can also use the electrical heart sensor to take an ECG with the ECG app.
The ECG app is currently available only in certain countries and regions. Learn where the ECG app is available. ECG isn't supported on Apple Watch SE.
Get the best results
Start with a good fit. Even under ideal conditions, Apple Watch may not be able to get a reliable heart rate reading every time for everybody. And for a small percentage of users, various factors may make it impossible to get any heart rate reading at all. But there are things you can do to help Apple Watch get the most consistent and best heart rate readings possible. Learn what else affects your reading.
Some anomalies may appear in the displayed data, resulting in occasional heart rate measurements that are abnormally high or low.
