Oura Ring Gen 4
9.4
Score / 10
Oura · Smart Ring
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.
Verdict
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.
- Order a sizing kit first — returns on the wrong size are a hassle.
Price
Around £350, plus roughly £6/month membership
Subscription
Required after 1-month trial for full metrics
Battery
7 days
Waterproof
100 m
How it works
Photoplethysmography (PPG) LEDs on the palm-side of the finger sample blood-volume waveforms. The ring computes HR, HRV and SpO₂ from the raw signal, fuses accelerometer data for movement, and reads skin temperature every minute. Overnight, on-device algorithms segment the night into sleep stages and derive a readiness score.
Sensors
- Red & infrared PPG (heart rate, HRV, SpO₂)
- NTC skin temperature sensor (0.13 °C resolution)
- 3-axis accelerometer
- Signal-processing chip (Gen 4 sensor array upgraded from Gen 3)
Metrics tracked
- Sleep stages (light, deep, REM) & sleep latency
- Nightly HRV, resting heart rate, respiratory rate
- Skin temperature deviation from personal baseline
- Blood oxygen (SpO₂) trend during sleep
- Daytime stress and steps, cardio load
- Menstrual cycle prediction from temperature
Strengths & weaknesses
Strengths
- 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
Weaknesses
- 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
Who it's for
Best for
- 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
Skip if
- Serious endurance athletes needing real-time pace/GPS
- People unwilling to pay a monthly subscription
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.
Ecosystem & privacy
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.
Data stored on Oura servers with pseudonymised IDs; GDPR/HIPAA options available. Users can request full data export and account deletion.
References
- Validation of a wearable ring for sleep trackingBehavioral Sleep Medicine · 2021
