Device comparisons
Google Pixel Watch vs Apple Watch: PPG Sensor and Health Ecosystem
Pixel Watch 3 pairs with Android phones and Apple Watch with iPhone, so the phone usually decides. Google lists a multi-path optical heart-rate sensor, red and infrared SpO2 sensors, ECG-compatible electrical sensors, a cEDA skin-conductance sensor and skin temperature on Pixel Watch 3. Apple lists an electrical heart sensor, third-generation optical heart sensor, blood oxygen and temperature sensors on Series 10. Both quote about a day of battery. No study has compared the two.
Devices
Google Pixel Watch 3, polished silver case with a porcelain band: product photograph from Google, 2024. Apple Watch Series 10, jet black aluminum with a black sport band: product photograph from Apple Newsroom, September 2024.
At a glance
This page does not list head-to-head accuracy numbers, so the scoreboard shows hardware differences only.
| Specification | Google Pixel Watch 3 | Apple Watch Series 10 |
|---|---|---|
| Optical sensorDiffers | Multi-path optical heart rate; red and infrared SpO2 | Third-generation optical heart sensor; blood oxygen sensor |
| Battery LifeDiffers | Up to 24 h (AOD); 36 h Battery Saver | Up to 18 h; 36 h Low Power Mode |
| Water ResistanceDiffers | 5 ATM + IP68 | 50 m (ISO 22810:2010); IP6X |
| WeightDiffers | 31 g (41 mm) / 37 g (45 mm), without band | 36.4 g (46 mm aluminum, GPS) |
| ECGDiffers | ECG-compatible electrical sensors | ECG app |
| Other sensorsDiffers | cEDA, skin temperature | Temperature sensor |
Primary rows only. The study tables further down list more results from the accuracy database.
Hardware specs
| Specification | Google Pixel Watch 3 | Apple Watch Series 10 |
|---|---|---|
| Optical sensorDiffers | Multi-path optical heart rate; red and infrared SpO2 | Third-generation optical heart sensor; blood oxygen sensor |
| Battery LifeDiffers | Up to 24 h (AOD); 36 h Battery Saver | Up to 18 h; 36 h Low Power Mode |
| Water ResistanceDiffers | 5 ATM + IP68 | 50 m (ISO 22810:2010); IP6X |
| WeightDiffers | 31 g (41 mm) / 37 g (45 mm), without band | 36.4 g (46 mm aluminum, GPS) |
| ECGDiffers | ECG-compatible electrical sensors | ECG app |
| Other sensorsDiffers | cEDA, skin temperature | Temperature sensor |
Hardware only. Study results are not repeated in this table. Differs marks values that are not the same. An em dash means this page did not publish that figure.
Specs verified on October 17, 2026: Google Pixel Watch technical specifications (Pixel Watch 3), Apple Watch Series 10 technical specifications, Gillinov et al. 2017, Med Sci Sports Exerc (exercise HR vs ECG, n=50), Perez et al. 2019, NEJM (Apple Heart Study), FDA De Novo DEN180042: Apple irregular rhythm notification.
Pros and cons
Google Pixel Watch 3
Pros
- Multi-path optical HR, red/IR SpO2, ECG-compatible electrical sensors
- cEDA skin-conductance sensor for body response tracking
- Up to 24 hours with always-on display; 36 hours Battery Saver
Cons
- Android only
- No peer-reviewed Pixel Watch 3 heart-rate validation verified by ChatPPG
Apple Watch Series 10
Pros
- Exercise HR concordance 0.92 with ECG (Gillinov 2017)
- ECG app and FDA-authorized irregular rhythm notifications
- Apple Heart Study: PPV 0.84 for irregular pulse notifications
Cons
- iPhone only
- Up to 18 hours battery (36 hours Low Power Mode)
What published studies show
One table per metric. These rows come from the accuracy database and are not repeated as a second card list. From the wearable accuracy database (v1.0.0).
Heart rate at rest2 studies
| 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 6R-R intervals and BPM at rest | 1.15%Mean absolute percentage error | ECG | n = 78, Lab: rest, talking, movie, before/ | Bonneval et al. (2025)Independent |
Heart rate during exercise11 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Google Pixel Watch 2mixed rest/stress/walking | 4.9 bpmMean absolute error | ECG chest strap (Zephyr BioHarness / | n = 45, Rest, cognitive stress, steady and intermittent walking in neutral/ | Gielen et al. (2026)Funding not reported |
| Google Pixel Watch 3 | 2.73%Mean absolute percentage error | ECG chest strap (Polar H7/ | n = 34, Maximal treadmill test | Lambe et al. (2026)Maker funded |
| Apple Watch Series 6 | High agreement in squat, deadlift, cable row (rho > 0.832)Study finding (no single number) | ECG chest strap (Polar H7/ | n = 29, Resistance exercise (5 exercises) | Støve et al. (2022)Funding not reported |
| Apple Watch SE | Significantly lower MAE than Polar Pacer Pro and Galaxy Watch 6Study finding (no single number) | ECG chest strap (Polar H7/ | n = 37, Low/ | Jeong et al. (2026)Independent |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 8 | Skin pigmentation did not predict error (P = 0.62); 50% of missing data from dark-skin participantsStudy finding (no single number) | ECG chest strap (Polar H7/ | n = 28, Rest, cycling, recovery | Mulholland et al. (2026)Independent |
| Apple Watch Series 9 | Less accurate for darker skin pigmentationStudy finding (no single number) | ECG chest strap (Polar H7/ | n = 30, 10-min treadmill | Chase et al. (2024)Independent |
5 more results in the database. Heart rate accuracy across devices →
Overnight heart rate1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 6 | ICC 0.96Intraclass correlation | ECG | n = 53, Overnight, sleep laboratory | Miller et al. (2022)Other maker funded |
| Apple Watch Series 6 | 1.5 bpm (absolute bias)Mean absolute error | ECG | n = 53, Overnight, sleep laboratory | Miller et al. (2022)Other maker funded |
HRV (RMSSD)2 studies
| 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 6 | ICC 0.67Intraclass correlation | ECG | n = 53, Overnight, sleep laboratory | Miller et al. (2022)Other maker funded |
| Apple Watch Series 6 | 22.5 ms (absolute bias)Mean absolute error (absolute bias) | ECG | n = 53, Overnight, sleep laboratory | Miller et al. (2022)Other maker funded |
Sleep stages (4-stage)4 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Google Pixel Watch | κ = 0.4Cohen's kappa | Polysomnography (PSG) | n = 30, Two Korean sleep centres, in-lab PSG | Lee et al. (2023)Independent |
| Google Pixel Watch | 63.5%Epoch-by-epoch agreement | Polysomnography (PSG) | n = 30, Two Korean sleep centres, in-lab PSG | Lee et al. (2023)Independent |
| Apple Watch Series 8 | κ = 0.53Cohen's kappa | Polysomnography (PSG) | n = 62, Sleep laboratory, 1 night | Schyvens et al. (2025)Funding not reported |
| Apple Watch Series 8 | 50.5–86.1% (range across stages)Sensitivity | Polysomnography (PSG) | n = 35, Inpatient, 1 night | Robbins et al. (2024)Other maker funded |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 8deep sleep duration | Deep sleep −43 minMean bias (signed) | Polysomnography (PSG) | n = 35, Inpatient, 1 night | Robbins et al. (2024)Other maker funded |
| Apple Watch Series 6 | 53%Epoch-by-epoch agreement | Polysomnography (PSG) | n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together | Miller et al. (2022)Other maker funded |
3 more results in the database. Sleep accuracy across devices →
Sleep vs wake (2-stage)3 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 8 | > 90% (all devices)Sensitivity | Polysomnography (PSG) | n = 62, Sleep laboratory, 1 night | Schyvens et al. (2025)Funding not reported |
| Apple Watch Series 8 | ≥ 95%Sensitivity | Polysomnography (PSG) | n = 35, Inpatient, 1 night | Robbins et al. (2024)Other maker funded |
| Apple Watch Series 6 | 88%Epoch-by-epoch agreement | Polysomnography (PSG) | n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together | Miller et al. (2022)Other maker funded |
| Apple Watch Series 6 | κ = 0.30Cohen's kappa | Polysomnography (PSG) | n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together | Miller et al. (2022)Other maker funded |
Blood oxygen (SpO2)8 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 7 | 3.5% (rest)Root-mean-square error | Medical-grade pulse oximeter | n = 36, Rest, COPD outpatients | Støve et al. (2023)Funding not reported |
| Apple Watch Series 6 | r = 0.89Pearson correlation | Medical-grade pulse oximeter | n = 265, Spot readings | Spaccarotella et al. (2022)Independent |
| Apple Watch Series 6 | −0.23 (LoA −3.49 to 3.04)Mean bias (signed) | Medical-grade pulse oximeter | n = 265, Spot readings | Spaccarotella et al. (2022)Independent |
| Apple Watch Series 7 | 2.2% (RMSE 2.9%)Mean absolute error | Medical-grade pulse oximeter | n = 49, Spot readings, with and without chronic pulmonary disease | Jiang et al. (2023)Independent |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 7 | 2.9%Root-mean-square error | Medical-grade pulse oximeter | n = 49, Spot readings, with and without chronic pulmonary disease | Jiang et al. (2023)Independent |
| Apple Watch Series 8 | Met ISO RMS ≤ 4% at normoxia and SpO2 < 90%; lowest bias and RMSD of the threeStudy finding (no single number) | Medical-grade pulse oximeter | n = 18, Induced hypoxemia (FiO2 14%, 12%, 10%), ISO 80601-2-61 | Walzel et al. (2023)Independent |
4 more results in the database. SpO2 accuracy across devices →
Atrial fibrillation detection4 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 6smartwatch ECG app, inconclusive tracings counted | 85% (spec 75%)Sensitivity | 12-lead ECG | n = 201, Tertiary cardiology service, single-lead ECG algorithms | Mannhart et al. (2023)Funding not reported |
| Apple Watch Series 6smartwatch ECG app, inconclusive tracings counted | 75%Specificity | 12-lead ECG | n = 201, Tertiary cardiology service, single-lead ECG algorithms | Mannhart et al. (2023)Funding not reported |
| Apple Watch + KardiaBand (SmartRhythm 2.0)AF episodes ≥ 1 h | 97.5% episode sensitivity (PPV 39.9%)Sensitivity | Insertable cardiac monitor | n = 24, Ambulatory, 31,348.9 h of recordings | Wasserlauf et al. (2019)Funding not reported |
| Apple Watch (irregular rhythm notification)PPG irregular pulse notification | PPV 0.84 (95% CI 0.76–0.92)Positive predictive value | ECG patch | n = 419297, Siteless pragmatic study; ECG patch after notification | Perez et al. (2019)Maker funded |
More results (1)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Kardia Band on Apple Watch (single-lead ECG)automated ECG read; 57 of 169 recordings non-interpretable | Sens 93% / spec 84% (interpretable recordings)Sensitivity | 12-lead ECG | n = 100, Before and after cardioversion | Bumgarner et al. (2018)Funding not reported |
VO2max estimate4 studies
Only maker-funded evidence for Pixel Watch on this metric.
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Google Pixel Watch 3 | 8.65% (bias −0.53 mL/kg/min)Mean absolute percentage error | Indirect calorimetry | n = 34, Free-living VO2max estimate vs maximal treadmill test | Lambe et al. (2026)Maker funded |
| Apple Watch Series 10 | 13.2% (MAE 6.79 mL/kg/min)Mean absolute percentage error | Indirect calorimetry | n = 40, Maximal treadmill test (modified Åstrand) | Lambe et al. (2026)Independent |
| Apple Watch | 13.31% (MAE 6.92 mL/kg/min)Mean absolute percentage error | Indirect calorimetry | n = 30, Maximal treadmill test (modified Åstrand) | Lambe et al. (2025)Independent |
| Apple Watch Series 7 | 15.79% (ICC 0.47)Mean absolute percentage error | Indirect calorimetry | n = 19, Graded cycle ergometer test | Caserman et al. (2024)Independent |
Energy expenditure (calories)7 studies
Only maker-funded evidence for Pixel Watch on this metric.
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Google Pixel Watch 3 | 15.02%Mean absolute percentage error | Indirect calorimetry | n = 34, Maximal treadmill test | Lambe et al. (2026)Maker funded |
| 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 4 | 13.5%–27.1% (range by intensity)Coefficient of variation | Indirect calorimetry | n = 25, Sitting, walking, running, sprints | Düking et al. (2020)Independent |
| Apple Watch Series 6 | 14.68–24.85% (poor in all activities)Coefficient of variation | Indirect calorimetry | n = 60, Sitting, walking, running, resistance, cycling | Hajj-Boutros et al. (2023)Funding not reported |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Apple Watch Series 8physical activity energy expenditure, 10 min | +21.6 kcalMean bias (signed) | Indirect calorimetry | n = 52, 10-min recumbent cycling intervals | Kostrna et al. (2026)Independent |
| Apple Watch Series 6walking | 19.8% walk / 24.4% runMean absolute percentage error | Indirect calorimetry | n = 20, Outdoor 2-km walk (6 km/ | Le et al. (2022)Independent |
1 more result in the database. Calories accuracy across devices →
Verdict
Choose by phone. Apple Watch has more independent accuracy evidence; Pixel Watch 3 adds a cEDA stress sensor and slightly longer quoted battery. Neither has been tested against the other.
Frequently asked questions
Is the Google Pixel Watch better than the Apple Watch?
It depends on your phone: Pixel Watch 3 needs Android and Apple Watch needs an iPhone. Apple Watch has more published independent validation; Pixel Watch 3 adds a cEDA skin-conductance sensor.
Is Pixel Watch as accurate as Apple Watch for heart rate?
No head-to-head study exists. Apple Watch reached 0.92 concordance with ECG during exercise in Gillinov et al. (2017); ChatPPG has not verified a peer-reviewed validation of Pixel Watch 3.
Which has longer battery life?
Google quotes up to 24 hours with always-on display (36 hours Battery Saver) for Pixel Watch 3; Apple quotes up to 18 hours (36 hours Low Power Mode) for Series 10.
Device research records
Datasets, papers and validation results for the models named on this page.