The Oura Ring 4 is the best smart ring you can buy right now. It's also a $349 device that becomes a paperweight if you stop paying $5.99 per month. That tension defines everything about this fourth-generation tracker: exceptional hardware, class-leading sleep insights, and a business model that asks you to keep your wallet open indefinitely.
We've worn the Ring 4 through weeks of sleep cycles, workouts, and daily life. What we found is a genuinely impressive piece of wearable technology that excels at its core mission–understanding your sleep and recovery–while falling short in ways that matter for some users. If you want the best sleep tracker that doesn't sit on your wrist, this is it. Just know what you're signing up for.
Design & Build
Oura built the Ring 4 from titanium, and it feels every bit as premium as that suggests. The ring is noticeably lighter than its predecessor, ranging from 3.3 to 5.2 grams depending on size. More importantly, Oura redesigned the internal sensors to sit flush against your finger rather than protruding like speed bumps. The difference in comfort is immediate–you can genuinely forget you're wearing it.
The size range now spans 4 to 15, a significant expansion from the Gen 3's 6-13 range. This opens the door for more users, though we still recommend using Oura's free sizing kit before committing. A proper fit matters enormously for sensor accuracy.
Here's the catch: that beautiful titanium scratches. Easily. The Silver finish hides wear best, but the Black, Stealth, and especially the Gold and Rose Gold options ($499) show every encounter with a doorframe, weight plate, or steering wheel. If you're paying premium prices for premium finishes, expect to see evidence of daily life within weeks.
Water resistance hits 100 meters, so swimming, showering, and washing dishes are all fine. The ring handles real life well–it just won't look pristine for long.
Performance & Features
Sleep tracking is where the Oura Ring 4 earns its reputation. The new 18-path multi-wavelength PPG sensor array delivers roughly 5% better accuracy than Apple Watch and 10% better than Fitbit in four-stage sleep classification, according to peer-reviewed research from Brigham and Women's Hospital.
The app translates all this data into three daily scores: Sleep, Readiness, and Activity. Sleep breaks down your night into light, deep, and REM stages, while Readiness synthesizes your recovery status to tell you whether to push hard or take it easy. These aren't gimmicks. After a few weeks, you'll start trusting the Readiness score to guide training decisions.
SpO2 (blood oxygen) tracking saw a 120% improvement in signal quality over Gen 3, resulting in more reliable overnight readings. Temperature tracking remains excellent and forms the backbone of Oura's standout cycle tracking features.
The app itself is polished and genuinely useful. Insights feel actionable rather than academic. You won't drown in data; you'll understand what your data means.
Health & Fitness
The Ring 4 tracks heart rate, heart rate variability (HRV), blood oxygen, skin temperature, and movement through its accelerometer. For passive, 24/7 health monitoring, it's exceptional. The lightweight form factor means you'll actually wear it to bed–something that can't be said for bulkier wrist-based trackers.
Women's health tracking deserves special mention. Cycle prediction accuracy, built on continuous temperature monitoring, rivals dedicated fertility trackers. For users who want health insights without a conspicuous device, this is genuinely best-in-class.
Where the Ring 4 stumbles is active workout tracking. Heart rate data during high-intensity exercise is unreliable. Vigorous movements–whether lifting, HIIT, or even aggressive cycling–introduce too much noise for consistent readings. Oura knows this and doesn't pretend otherwise; the ring excels at recovery metrics, not real-time exercise tracking. If you need accurate mid-workout heart rate zones, pair it with a chest strap or stick with a smartwatch.
Battery Life
Oura advertises up to 8 days of battery life. We consistently got 5 to 6 days with typical use–sleep tracking enabled, SpO2 monitoring on, and occasional workout logging. That's still good, better than most smartwatches, but the gap between marketing and reality is worth noting.
Charging happens via a small stand rather than a case. There's no battery backup or on-the-go charging option, which feels like a miss at this price point. You'll need to plan your charging around your sleep schedule, since wearing it to bed is the whole point.
Who It's For / Who Should Skip
Buy the Oura Ring 4 if: - Sleep quality is your primary health focus - You want 24/7 tracking in an invisible form factor - Cycle tracking accuracy matters to you - You're comfortable with subscription-based software - You already dislike sleeping in a smartwatch
Skip it if: - You refuse to pay ongoing subscriptions for hardware you own - Accurate workout heart rate tracking is essential - You expect pristine aesthetics long-term - You own a Gen 3 Oura Ring (the upgrade isn't dramatic) - You need a charging case for travel
The Verdict
Score: 86/100
The Oura Ring 4 is the best smart ring available today, full stop. Its sleep tracking leads the industry, the comfort improvements are substantial, and the app delivers insights that actually change behavior. The scientific validation behind its algorithms isn't marketing fluff–it's peer-reviewed research.
But that mandatory $69.99/year subscription casts a long shadow. You're not buying a device; you're buying into a service. The hardware scratches easily, workout tracking is a known weakness, and battery life falls short of promises. For Gen 3 owners, the improvements don't justify the upgrade cost.
For everyone else serious about sleep and recovery tracking, the Oura Ring 4 is the one to get–just budget for the long haul.