Device research record
Apple Watch Series 9+
Signals and sensors
From the device record. Fields the source does not state are left out.
- Maker
- Apple
- Form factor
- Wrist
- Series
- Series 9+
- Family
- Apple Watch
- Signals recorded
- PPG, Accelerometer, ECG
- Also called
- Apple Watch Series 9, Apple Watch Ultra, Watch S9+, Series 9+
What published studies show
Results quoted from 2 published validation studies, each against a clinical reference. A result applies to the model and protocol tested, not to every model the brand sells. From the wearable accuracy database (v1.0.0).
Heart rate at rest1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 9 / Ultra 2 | 5.91% (MAE 3.73 bpm)Mean absolute percentage error | Polar H10 + Kubios HRV | n = 39, Serial morning measurements over 14 days, 316 readings | O'Grady et al. (2024)Independent |
- Apple Watch Series 9 / Ultra 25.91% (MAE 3.73 bpm)
Mean absolute percentage error · vs Polar H10 + Kubios HRV · n = 39, Serial morning measurements over 14 days, 316 readings
O'Grady et al. (2024) Independent
Heart rate during exercise1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 9 | Less accurate for darker skin pigmentationStudy finding (no single number) | ECG chest strap (Polar H7/H10) | n = 30, 10-min treadmill | Chase et al. (2024)Independent |
- Apple Watch Series 9Less accurate for darker skin pigmentation
Study finding (no single number) · vs ECG chest strap (Polar H7/H10) · n = 30, 10-min treadmill
Chase et al. (2024) Independent
HRV (RMSSD)1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 9 / Ultra 2 | 28.88% (MAE 20.46 ms)Mean absolute percentage error | Polar H10 + Kubios HRV | n = 39, Serial morning measurements over 14 days, 316 readings | O'Grady et al. (2024)Independent |
- Apple Watch Series 9 / Ultra 228.88% (MAE 20.46 ms)
Mean absolute percentage error · vs Polar H10 + Kubios HRV · n = 39, Serial morning measurements over 14 days, 316 readings
O'Grady et al. (2024) Independent
Energy expenditure (calories)1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 9 | Inconsistent across all groupsStudy finding (no single number) | Indirect calorimetry | n = 30, 10-min treadmill | Chase et al. (2024)Independent |
- Apple Watch Series 9Inconsistent across all groups
Study finding (no single number) · vs Indirect calorimetry · n = 30, 10-min treadmill
Chase et al. (2024) Independent
Comparisons
Head-to-head comparisons for this brand.
- Whoop vs Apple Watch: What the Sleep-Lab Studies Found
- Garmin vs Apple Watch: PPG, ECG & Battery Compared
- Apple Watch Ultra 2 vs Garmin Fenix 8: Specs Guide
- Fitbit vs Apple Watch: PPG Sensor Accuracy and Health Features
- Samsung Galaxy Watch vs Apple Watch: PPG Sensor and Health Features
- Oura Ring vs Apple Watch: Finger PPG vs Wrist PPG Accuracy
- Google Pixel Watch vs Apple Watch: PPG Sensor and Health Ecosystem
- Withings vs Apple Watch: ScanWatch 2 ECG, SpO2 and PPG Compared
Articles that mention Apple Watch Series 9+
- PPG Garmin Apple Watch Validation
- Apple Watch hypertension notifications: how PPG spots possible high blood pressure
- PPG Remote Patient Monitoring Role
- Remote Patient Stress Monitoring: PPG Wearables in Telehealth
- Stress Tracker Accuracy Guide: What Wearables Actually Measure
- PPG Sensors in Wearable Technology: From Wrist Bands to Smart Rings and Earbuds
- Fitbit Heart Rate Accuracy: What Validation Studies and Real-World Data Show
- PPG Wearable Form Factors: Ring, Patch, Earbud, and Headband Sensor Design