Apple Watch Ultra 3 vs Withings Body Scan
Two devices, the same questions: what does it actually measure, how good is the data, what does it cost to keep using, and who is it for.
Apple Watch Ultra 3
The most capable multi-sensor wristwatch on the market. Strong at ECG, everyday health nudges, GPS accuracy, and app ecosystem — weaker for high-fidelity HRV research than dedicated rings and straps.
Full review →Withings Body Scan
The most data-dense consumer scale you can buy: segmental body composition, six-lead ECG, vascular age and nerve activity in a single step-on.
Full review →| Spec | Apple Watch Ultra 3 | Withings Body Scan |
|---|---|---|
| Price | Around £799 | Around £350, plus roughly £10/month Withings+ |
| Subscription | Optional (Fitness+, some third-party apps) | Optional Withings+ unlocks vascular age and nerve activity |
| Form factor | 49 mm titanium case, sapphire crystal, action button | Glass scale with retractable handle bar |
| Battery life | 36 h typical, 72 h low-power | 12 months rechargeable |
| Water resistance | 100 m (WR100 + EN13319 dive) | IPX3 |
| Platforms | iOS only (watchOS) | iOS, Android |
| Sensors |
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| Metrics tracked |
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| Data quality | GPS and workout HR accuracy are excellent. ECG rhythm classification is FDA-cleared for atrial fibrillation. HRV is sampled sparsely — trend only, not intra-day. | Bio-impedance accuracy is decent for trend, poor for absolute vs DEXA. ECG rhythm strip is FDA-cleared. PWV correlates with cardiovascular age but is not a diagnostic tool. |
| Ecosystem | Apple Health, HealthKit, Fitness+, Strava, Zwift, Training Peaks and thousands of third-party apps. Data export via Apple Health XML. | Withings Health Mate; syncs with Apple Health, Google Health Connect, Strava, MyFitnessPal. |
| Privacy | Health data is end-to-end encrypted when iCloud Advanced Data Protection is enabled. Local processing on-device where possible. | GDPR-compliant, EU-hosted. Full data export supported. |
Apple Watch Ultra 3
- Excellent GPS accuracy with dual-frequency L1+L5
- Only major consumer wearable with medical-grade single-lead ECG
- Best-in-class app ecosystem and notifications
- Rugged case, long battery for a smartwatch
- HRV sampled once per day — insufficient for deep recovery analytics
- iPhone-locked; useless with Android
- Heavy on the wrist for sleep tracking
- iPhone users who want one device for training, health and productivity
- Outdoor athletes needing dive/altitude/GPS-grade metrics
- Android users
- People whose main goal is deep sleep/HRV research (see Oura, WHOOP)
Withings Body Scan
- Segmental composition = detect asymmetry that a wrist device cannot
- One of very few consumer devices tracking vascular age
- Long battery life, calm hardware design
- Bio-impedance is not DEXA — treat trends, not absolutes
- Some metrics gated behind subscription
- Standing measurement means hydration confounds accuracy
- Users tracking body-composition change under training or GLP-1 protocols
- People with cardiovascular risk who want daily vascular-age nudges
- Clinical body-composition assessment (use DEXA)
- Users who take multiple daily weigh-ins — hydration noise dominates
The everyday-carry answer for iPhone users who want one device to cover everything except deep sleep research.
The most sensor-rich consumer scale. Best used as a monthly baseline + trend tool, not a daily obsession.
Other comparisons
Scores reflect our own testing criteria — data quality, what the device measures that matters for healthspan, and total cost of ownership including subscription. Prices are manufacturer list prices and change often; check before buying. Some links are affiliate links, which never affect a score — see our affiliate disclosure.