Smartwatch Health Features Explained — What It Actually Measures and What's Accurate?

Objective explanation of smartwatch health features — SpO2, blood pressure, HRV — how accurate are they?

What Does the Watch Actually Measure?

Heart Rate ❤️

Accuracy: Very high (±3-5 bpm) — medically acceptable for daily monitoring.

Blood Oxygen SpO2 🩸

Accuracy: Good for general monitoring (±2%). Not a substitute for hospital equipment.

Blood Pressure 🔴

Accuracy: Low in most budget watches. Requires manual calibration. Don't rely on it medically.

Sleep Tracking 😴

Accuracy: Medium — good for knowing general patterns, not accurate for each stage.

HRV (Heart Rate Variability)

Accuracy: Good for measuring recovery and general stress.

Conclusion

A smartwatch is a great monitoring tool for daily life — but it doesn't replace a doctor.