Oura Ring 4 Review: Still Worth Buying Now the Ring 5 Is Out?

The Oura Ring 4 was Oura's flagship from October 2024 until the Ring 5 arrived in June 2026, and it's now the cheaper way into Oura's ecosystem. On Amazon UK it's £239 for the gold finish in size 9, against £399 for a Ring 5, and it runs the same app with the same membership. If it fits you and you can live with a slightly chunkier ring, it's the smarter buy for most people. If you have slim fingers, the Ring 5's smaller shell is worth the extra.

Sleep is still the reason to buy one. Oura's rings have more independent validation behind their sleep tracking than almost any consumer wearable, and that evidence applies to the Ring 4 at least as well as to the newer model. What you don't get is GPS, a screen, or a training coach, and you'll pay £69.99 a year on top to see most of your data.

Check Oura Ring 4 prices and sizes on Amazon£239

Who it's for

The Ring 4 suits anyone who wants solid sleep and recovery data without strapping a watch on at night. People who sleep badly, shift workers, new parents and anyone tracking their menstrual cycle get the most from it. It also makes a good partner for a running watch, which handles GPS and workouts while the ring takes the night shift.

It's a weaker fit for heavy lifters, since a ring sits exactly where a barbell presses into your palm, and for anyone who wants live numbers on their wrist. It's also hard to recommend if you object to subscriptions, because the membership is close to mandatory. If you're torn between a ring and a strap, our WHOOP vs Oura comparison covers that choice.

Design, sizing and the Ring 4 Ceramic

Oura's Ring 4 spec page lists the titanium Ring 4 at 7.9mm wide and about 2.88mm thick, weighing 3.3 to 5.2g depending on size. The exterior is titanium with a PVD or DLC coating depending on finish, the inner shell is titanium too, and the sensors sit recessed 0.3mm into the inside of the band. Next to most wedding bands it looks bigger, which is the single biggest reason people now look at the Ring 5 instead.

Sizing matters more than with any other wearable. Oura sells by size, and the Amazon listing we link is specifically gold in size 9; you pick your size and finish on the page, and the price can change between variants. The listing title says a sizing kit is included, but don't use that as a reason to guess. Oura ring sizes don't line up with jewellery sizes, so get the Ring 4 sizing kit first, wear the right dummy ring for at least 24 hours including a night, and only then order. Use the white Ring 4 sizers specifically: Oura says Ring 5 sizing is slightly different.

The Oura Ring 4 Ceramic is a real, separate model. It swaps the titanium exterior for zirconia ceramic, which Oura picked for scratch resistance and colour, over the same titanium inner shell. The trade-off is bulk. At 3.51mm thick and 5.1 to 8.1g, it's the heaviest current Oura, so it suits people who care more about how the ring looks after a year of knocks than about how it feels at night.

What it tracks

The Ring 4 uses green and infrared light to measure heart rate around the clock, plus HRV and breathing rate during sleep. Red and infrared LEDs estimate blood oxygen overnight, a digital sensor tracks changes in skin temperature, and an accelerometer logs movement all day.

Each morning that feeds three headline scores. Sleep looks at total sleep, efficiency, timing and stages. Readiness blends last night's sleep with resting heart rate, HRV and your temperature trend. Activity counts steps and movement against a daily target. Temperature data also drives period prediction and cycle insights, and the ring links with apps such as Natural Cycles and Flo. Oura Advisor, the AI assistant in the app, will explain your own numbers in plain English if the graphs don't mean much to you.

Accuracy

The sleep evidence is strong. A 2025 systematic review and meta-analysis pooled six studies with 388 participants comparing Oura rings with polysomnography or actigraphy. It found no statistically significant difference for total sleep time, sleep efficiency, time awake, time to fall asleep, or light, deep and REM sleep. Total sleep time came in about three minutes short of the reference on average. That's as good as consumer sleep tracking gets.

Heart rate and HRV hold up well overnight too, with a caveat. In a study of 114 adults in two sleep labs, Oura's overnight heart rate and HRV correlated strongly with ECG. HRV was the weaker of the two, especially in people over 45, and accuracy improved when the data was averaged over at least 30 minutes. In practice that means the nightly average is trustworthy, but don't read too much into one five-minute dip.

Daytime numbers are rougher. A lab and free-living study of step counts and energy expenditure found Oura tracked big changes in activity well and correlated strongly with research monitors, but it underestimated energy burn as exercise got harder and miscounted steps by a wide margin for some individuals. Treat calorie figures as a rough guide.

None of these studies was run on the Ring 4 specifically; they span several Oura generations. Oura's own pitch for the Ring 4 was improved sensing, and there's no reason to expect it to do worse than the rings tested. Like any wearable, it can be off on a single night, so watch weekly trends. It also isn't a diagnostic tool, so see your GP if you think you might have sleep apnoea. Our guide to sleep and muscle recovery explains why those trends are worth tracking.

Battery and charging

Oura rates the Ring 4 at 5 to 8 days per charge, and the Amazon listing calls it "up to 8 days". Size makes a real difference: smaller rings hold smaller batteries, so if you're a size 5 or 6, plan on charging every five days or so. A charge takes 20 to 80 minutes depending on how low it is.

The Ring 5 rates 6 to 9 days, so it's about a day better on paper. Either way, the habit that works is charging during a shower or while you're at your desk, then putting it straight back on. The most common owner complaint about battery isn't capacity; it's leaving the ring on the charger at bedtime and losing a night's data.

See today's Oura Ring 4 price on Amazon

The membership: what it costs and what you lose without it

Oura's UK membership is £5.99 a month or £69.99 a year, and new members get the first month free. Without it, Oura says the ring and the app keep working, but the insights, personal health data and features you can see are "much more limited". You can still export your data as a CSV file from the Membership Hub.

Put plainly, the detailed sleep breakdown, the explanations behind your scores and the extra features are what you're paying for, and they're why people buy an Oura at all. Budget for it from day one. A £239 Ring 4 on the annual plan costs about £379 over two years and £449 over three. The same sums for a £399 Ring 5 come to about £539 and £609. That gap is the whole case for the older ring.

Ring 4 vs Ring 5: who should still buy the 4

We've reviewed the newer ring in full in our Oura Ring 5 review, and there's a full side-by-side in our Oura Ring 5 vs 4 guide. The short version: Oura says the Ring 5 has 40% less volume, at 6.09mm wide and 2.28mm thick, and it adds about a day of battery. Software features are identical and your membership carries over.

Buy the Ring 4 if:

• You can get it for £150 or more below the Ring 5, as you can on Amazon right now
• You need size 4, 5, 14 or 15, which the Ring 5 doesn't make
• You have average or larger fingers and don't mind a ring you'll notice
• You want the Ceramic finish for scratch resistance

Buy the Ring 5 instead if you have slim fingers, wear rings on several fingers, or found older Ouras bulky. If you'd rather avoid a subscription altogether, our Ultrahuman Ring Air review and Samsung Galaxy Ring review cover the main subscription-free rivals. More sleep and recovery kit lives in our recovery section.

Recommended reads

• Oura Ring 5 review
• Oura Ring 5 vs Ring 4: which should you buy?
• WHOOP vs Oura
• Ultrahuman Ring Air review
• Sleep and muscle recovery