Oura Ring Gen 4 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.
Oura Ring Gen 4
The best-in-class passive sleep and HRV tracker. A titanium ring you forget you're wearing that produces some of the most defensible sleep-stage and readiness data on the consumer market.
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 | Oura Ring Gen 4 | Withings Body Scan |
|---|---|---|
| Price | Around £350, plus roughly £6/month membership | Around £350, plus roughly £10/month Withings+ |
| Subscription | Required after 1-month trial for full metrics | Optional Withings+ unlocks vascular age and nerve activity |
| Form factor | Titanium ring, 7 sizes | Glass scale with retractable handle bar |
| Battery life | 7 days | 12 months rechargeable |
| Water resistance | 100 m | IPX3 |
| Platforms | iOS, Android | Same |
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| Data quality | Sleep-stage agreement with polysomnography is in the 79–80% range for prior generations — better than most wrist wearables. HRV and RHR trends are highly reliable when compared over weeks. Absolute values are calibrated to personal baselines, so cross-device comparisons are less meaningful than trend. | 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 | Native app on iOS and Android. Exports to Apple Health and Google Health Connect. Third-party integrations via Zapier and the Oura API for developers. | Withings Health Mate; syncs with Apple Health, Google Health Connect, Strava, MyFitnessPal. |
| Privacy | Data stored on Oura servers with pseudonymised IDs; GDPR/HIPAA options available. Users can request full data export and account deletion. | GDPR-compliant, EU-hosted. Full data export supported. |
Oura Ring Gen 4
- Sleep-stage classification validated against polysomnography with reasonable agreement
- Passive, comfortable form factor — high adherence over months
- Excellent HRV trend data and readiness scoring
- Long-term temperature baseline detects illness onset early
- Membership is mandatory for full data — the ring alone is limited
- Poor for high-intensity exercise tracking (no GPS, no chest-strap accuracy)
- Screen-free — you must open the app to see anything
- Anyone whose primary goal is sleep and recovery optimisation
- Users who dislike wrist wearables or want a discreet device
- Longevity tracking of resting HR and HRV trends over months to years
- Serious endurance athletes needing real-time pace/GPS
- People unwilling to pay a monthly subscription
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
If sleep and recovery are the metrics you care about most and you'll wear the device consistently, the Gen 4 remains the benchmark. Skip it only if you refuse subscriptions or need one device to also do serious training analytics.
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.