Device comparisons
Samsung Galaxy Watch vs Apple Watch: PPG Sensor and Health Features
Samsung Galaxy Watch7 and Watch Ultra pair only with Android phones; Apple Watch pairs only with iPhone, so the phone usually decides. Both have an FDA-cleared or authorized ECG feature. Samsung adds cuffless blood pressure estimates that need cuff calibration every 28 days. In independent testing, Apple Watch had the lowest heart-rate error and Samsung's older Gear S2 the highest of seven devices (Shcherbina 2017); no study has compared current models.
Devices
Samsung Galaxy Watch (Watch7 / Ultra)
SmartwatchDevice guideApple Watch (Series 10 / Ultra 2)
SmartwatchDevice guideSamsung Galaxy Watch7 in green: product photograph from Samsung’s gallery. 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 | Samsung Galaxy Watch (Watch7 / Ultra) | Apple Watch (Series 10 / Ultra 2) |
|---|---|---|
| BatteryDiffers | 425 mAh / 300 mAh (Watch7 44/40 mm); Ultra up to 100 h Power Saving | Up to 18 h (Series 10); up to 36 h (Ultra 2) |
| Water ResistanceDiffers | 5ATM + IP68 (Watch7); 10ATM + IP68 (Ultra) | 50 m (Series 10); 100 m (Ultra 2) |
| ECGDiffers | ECG Monitor app (FDA K201168) | ECG app; irregular rhythm notifications |
| Blood pressureDiffers | Cuff-calibrated estimates; recalibrate every 28 days | — |
| PhoneDiffers | Android only | iPhone only |
Primary rows only. The study tables further down list more results from the accuracy database.
Hardware specs
| Specification | Samsung Galaxy Watch (Watch7 / Ultra) | Apple Watch (Series 10 / Ultra 2) |
|---|---|---|
| BatteryDiffers | 425 mAh / 300 mAh (Watch7 44/40 mm); Ultra up to 100 h Power Saving | Up to 18 h (Series 10); up to 36 h (Ultra 2) |
| Water ResistanceDiffers | 5ATM + IP68 (Watch7); 10ATM + IP68 (Ultra) | 50 m (Series 10); 100 m (Ultra 2) |
| ECGDiffers | ECG Monitor app (FDA K201168) | ECG app; irregular rhythm notifications |
| Blood pressureDiffers | Cuff-calibrated estimates; recalibrate every 28 days | — |
| PhoneDiffers | Android only | iPhone only |
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: Shcherbina et al. 2017, J Pers Med (seven wrist devices), Gillinov et al. 2017, Med Sci Sports Exerc (exercise HR vs ECG, n=50), Han et al. 2023, Hypertension Research (Galaxy Watch BP, 760 users), Samsung: Galaxy Watch7 and Watch Ultra compared with previous models, Samsung Support: Galaxy Watch Ultra battery, Samsung Support: blood pressure on Galaxy Watch, Samsung Support: watch and phone compatibility, FDA 510(k) K201168: Samsung ECG Monitor App, Apple Watch Series 10 technical specifications, Apple Watch Ultra 2 technical specifications, FDA De Novo DEN180042: Apple irregular rhythm notification.
Pros and cons
Samsung Galaxy Watch (Watch7 / Ultra)
Pros
- ECG Monitor app (FDA 510(k) K201168)
- Blood pressure estimates after cuff calibration
- Watch Ultra: up to 100 h in Power Saving mode; 10ATM + IP68
Cons
- Requires an Android phone (not compatible with iPhone)
- Blood pressure needs recalibration every 28 days and is not for diagnosis
- Older Gear S2 had the highest HR error of seven devices (Shcherbina 2017)
Apple Watch (Series 10 / Ultra 2)
Pros
- Exercise HR concordance 0.92 with ECG (Gillinov 2017)
- Lowest heart-rate error of seven devices (Shcherbina 2017)
- ECG app and FDA-authorized irregular rhythm notifications
Cons
- Series 10: up to 18 hours battery
- Requires an iPhone
- No blood pressure estimates
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 rest3 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch Active2 | 9.4 bpm (seated rest)Mean absolute error | Holter ECG | n = 23, Rest, sedentary, low- and high-intensity phases | Nissen et al. (2022)Independent |
| 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 |
|---|---|---|---|---|
| Samsung Galaxy Watch Active2squats | 6.1 bpm (squats)Mean absolute error | Holter ECG | n = 23, Rest, sedentary, low- and high-intensity phases | Nissen et al. (2022)Independent |
| Samsung Galaxy Watch 6 | Significantly higher MAE than Apple Watch SE and Verity SenseStudy finding (no single number) | ECG chest strap (Polar H7/ | n = 37, Low/ | Jeong et al. (2026)Independent |
| Samsung Gear S2 | Highest overall error of 7 devicesStudy finding (no single number) | ECG | n = 60, Sitting, walking, running, cycling | Shcherbina et al. (2017)Independent |
| Samsung Galaxy Watch6 | −2.67 bpm (LoA −16.90 to 11.57)Mean bias (signed) | ECG chest strap (Polar H7/ | n = 55, Maximal incremental treadmill test | Inoue et al. (2026)Funding not reported |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| 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 |
7 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 |
|---|---|---|---|---|
| Samsung Galaxy Watch5 | κ = 0.42Cohen's kappa | Polysomnography (PSG) | n = 22, Two Korean sleep centres, in-lab PSG | Lee et al. (2023)Independent |
| Samsung Galaxy Watch5 | 64.9%Epoch-by-epoch agreement | Polysomnography (PSG) | n = 22, 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 |
Total sleep time1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Gear Sport | r = 0.59Pearson correlation | Research actigraphy | n = 45, Home, 7 days | Asgari Mehrabadi et al. (2020)Independent |
Blood oxygen (SpO2)10 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch5 | Met ISO RMS ≤ 4% at normoxia and SpO2 < 90%Study 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 |
| Samsung Galaxy Watch4 | RMSD 1.8%Root-mean-square error | Arterial blood gas (SaO2) | n = 24, Hypoxia lab, SaO2 plateaus 70–100%, FDA/ | Browne et al. (2025)Independent |
| Samsung Galaxy Watch4 | RMSE 2.54 points (overnight, vs PSG oximetry)Root-mean-square error | PSG pulse oximetry | n = 51, In-lab overnight PSG, continuous SpO2 | Browne et al. (2024)Maker funded |
| 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 |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| 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 |
7 more results in the database. SpO2 accuracy across devices →
Atrial fibrillation detection4 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch3smartwatch 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 |
| Samsung Galaxy Watch3smartwatch 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 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 |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| 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 |
1 more result in the database. AFib accuracy across devices →
VO2max estimate3 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| 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
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch5physical activity energy expenditure, 10 min | +56.76 kcalMean bias (signed) | Indirect calorimetry | n = 50, 10-min recumbent cycling intervals | Kostrna et al. (2026)Independent |
| Samsung Galaxy Watch6 / Watch7 | 10.10–12.55%Mean absolute percentage error | Indirect calorimetry | n = 148, 27-min intermittent treadmill running | Ferreira et al. (2026)Funding not reported |
| 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 |
More results (2)
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| 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 |
| 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 |
2 more results in the database. Calories accuracy across devices →
Respiratory rate1 study
Only maker-funded evidence for Samsung on this metric.
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch | RMSE 1.13 breaths/min (overnight average)Root-mean-square error | Polysomnography (PSG) | n = 195, Overnight PSG, nasal thermocouple reference | Jung et al. (2023)Maker funded |
Blood pressure3 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch5 | SBP −0.34 / DBP +0.62 mmHgMean bias (signed) | Validated cuff (Omron M4) | n = 37, 28 days after one calibration | Walzel et al. (2026)Funding not reported |
| Samsung Galaxy Watch Active2 | 83% (spec 41%) for hypertensionSensitivity | 24-h ambulatory BP monitor | n = 40, 24-h ambulatory BP monitoring | Falter et al. (2022)Independent |
| Samsung Galaxy Watch (BP) | Pre/post calibration SBP error 6.8 ± 5.6 mmHgStudy finding (no single number) | Cuff used for calibration | n = 760, Real-world, 4 weeks post calibration | Han et al. (2023)Funding not reported |
Skin temperature1 study
Only maker-funded evidence for Samsung on this metric.
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Samsung Galaxy Watch5 | r = 0.42 vs oral temperaturePearson correlation | Oral thermometer | n = 85, Nightly wrist skin temperature vs oral temperature on waking | Kim et al. (2026)Maker funded |
Verdict
Choose by phone: Samsung for Android, Apple Watch for iPhone. Apple has the stronger independent heart-rate evidence; Samsung adds blood pressure estimates that require regular cuff calibration.
Frequently asked questions
Which has better heart rate accuracy: Samsung or Apple Watch?
No study has compared current models. In Shcherbina et al. (2017), Apple Watch had the lowest heart-rate error of seven wrist devices and the Samsung Gear S2 the highest.
Is Samsung Galaxy Watch blood pressure accurate?
Samsung requires calibration against a cuff every 28 days and says the feature is not intended for diagnosis. A real-world feasibility study of 760 Galaxy Watch users (Han 2023) examined measurement stability after calibration, not accuracy against a cuff.
Can I use Samsung Galaxy Watch with iPhone?
No. Samsung lists Galaxy Watch4 and later Wear OS models as incompatible with iPhone.
Device research records
Datasets, papers and validation results for the models named on this page.