Heart rate

How many times your heart beats a minute, right now. Apple Watch measures it with light sensors on the back of the watch.

Heart rate is beats per minute, and it changes all day long. Climbing stairs shows up in it. So does a scary movie.

Apple Watch flashes green lights against your wrist hundreds of times a second and measures how much light your pulsing blood absorbs. It checks in the background while you wear it and keeps a close eye during workouts. Apple Watch Series 12 and Ultra 4 can measure as often as every five seconds. Touching the Digital Crown on supported models uses electrical sensors for a faster reading.

Readings aren't perfect for everyone. A loose band, cold skin, some tattoos and jerky movements like tennis or boxing can confuse the sensor, and odd spikes or dips do happen.

Exercise raises it, and so do stress, strong emotions, hot and humid weather and a fever. Standing up can bump it briefly. Some medicines slow it.

Pajdo shows each day's low, average and high, and uses your workout heart rate for heart rate zones and training load.

This is general wellness information, not medical advice. If a number worries you, or stays away from your usual for a while, talk to a doctor.

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