Blood oxygen

How much oxygen your red blood cells are carrying, as a percentage. Apple Watch estimates it on supported models, in supported regions.

Blood oxygen is the percentage of oxygen your red blood cells carry from your lungs to the rest of your body. Most healthy people sit between 95% and 100%.

The Blood Oxygen app works on Apple Watch Series 6 or later and every Apple Watch Ultra, not on Apple Watch SE, and only in some countries and regions. On some US models the reading is worked out on iPhone and shows up in Apple Health. Apple Watch takes readings in the background, usually when you're still, and you can take a 15-second one yourself. Apple says these readings aren't for medical use.

Wrist readings are fussy. Cold skin, some tattoos, movement and a loose band can all get in the way of a reading, and even medical pulse oximeters can be off by a few percentage points.

It's a little lower during sleep, and lower at higher altitude, where there's less oxygen in the air.

Pajdo shows your readings next to your own usual range. He doesn't use blood oxygen to set his mood.

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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