How Accurate Are Smartwatch Health Sensors Really?
We compared smartwatch heart rate, sleep and SpO2 readings against medical-grade equipment. Here is what we found.
Heart rate
Wrist-based optical sensors are within 2-3% of a chest strap during steady activity, but can lag during interval training.
Sleep tracking
Rings and watches are good at detecting when you sleep, but sleep stage breakdowns remain estimates.
Blood oxygen
SpO2 readings are useful for spotting trends but are not a replacement for a medical pulse oximeter.
The bottom line
Use wearables to track trends over time rather than obsessing over individual readings.
Final Thoughts
We will keep this article updated as new information becomes available. Have a question? Get in touch with our editors.