What’s the Deal With Pulse Oximeters?

Here’s what to know about devices that can measure blood oxygen saturation

Close-up of human hand using a home pulse oximeter from Innovo to measure heartbeat and blood oxygen saturation.
Pulse oximeters measure the percentage of your red blood cells that are carrying oxygen by beaming different wavelengths of light into your finger after it’s clipped on. Photo: Smith Collection/Gado/Getty Images