Oura Ring 4 Review: The Almost Perfect Smart Fitness Ring

The Oura Ring 4 fully convinces in testing and reaches 1st place in the best list. At test time, no other smart ring can surpass the Oura in terms of equipment and operation. The sensors work reliably, both when measuring body functions and when tracking sports. In addition, there are practical extras such as pregnancy support and now also AI functions in the app. The battery life is good, only a practical charging case is missing.

Pros

• Super equipment
• Outstanding operation
• Practical extras

Cons

• No charging case available
• Temperature measurement only during sleep

The Oura Ring 4 (Smart Ring, size 11) proves itself in testing as an outstanding fitness ring.

Sizing

It is available in 12 sizes — the right size for the finger can be determined with a sizing kit.

Flat Inner Surface

On the inside, the Oura Ring is now completely flat.

Improved Sensors

The sensors have been improved and now measure more accurately.

Function Range

The range of functions for body analysis and sport tracking is enormous.

Battery Life

The battery life of the smart ring is excellent.

Missing Charging Case

A practical charging case for more battery life on the go is not available.

Charging Method

The ring is charged on the charging station with a USB-C cable.

Test Result

The Oura Ring 4 received a test verdict of Very Good (1.2) with a price assessment of Expensive (3.9). It ranks 1 of 11 in the smart rings best list.

Companion App

The associated app is the Oura app, available for both Android and iOS — making the smart ring compatible with almost all smartphones, including iPhones.

Water Resistance

Water resistance is rated to 100 metres (10 ATM by manufacturer specification).

Step Counter Accuracy

The mean step count accuracy is rated very good with measurement variations of 1.7 percentage points.

Battery Specifications

Battery capacity is 25.5 mAh. Battery life measurement is 6.9 days. The test ring was size 10. Charge time according to manufacturer specifications is 1 hour 19 minutes.

Charging Case

A practical charging case is available, but not included in delivery.

Test Date

Tested on 22 April 2025.

As a pioneer in the market for smart fitness rings, Oura has gathered considerable experience, and this is also evident in the test of the current Oura Ring 4. It has made up for many of the things criticised about the predecessor model Oura Ring 3, and is at the test time the top recommendation in the smart ring best list.

Flat Inner Design

The most striking change to the design is that the sensors no longer sit in raised areas; instead, the inner side of the ring is now completely flat.

Expanded Size Range

The selection of ring sizes has been expanded. The Oura Ring 4 is now available in twelve US-scale sizes, from 4 to 15. Anyone who does not yet know their own ring size can request a sizing kit and use it to determine this.

Sensor Improvements

According to the manufacturer's own statement, Oura has significantly improved the built-in sensors. With the measurement of heart rate or blood oxygen content, this is not so easy to assess, or rather, the measurements of the predecessor were already satisfactory. A noticeable improvement was noticed with the step counter, however. It now works much more accurately than before.

In general, the offer of functions is outstanding. The measurement of body data is comprehensive. During sleep, the sleep phases are reliably recorded, and the Oura Ring 4 also monitors breathing and body temperature.

Body Temperature Limitation

There is no option to switch on body temperature measurement at the touch of a button. It works only passively, during sleep.

Endurance and Health Tracking

In addition, Oura calculates a value for endurance performance, can predict menstruation, or support pregnancy with timetables and information about changes in the body.

Compatibility

All this is visible in the Oura app, which can be installed on Android or iOS. The smart ring is therefore compatible with almost all smartphones, including iPhones.

New AI Features

New are AI functions in the app such as the Oura Advisor, which gives recommendations.

If you want to use the Oura Ring 4 for sport, there are also many possibilities here. With the app, a large number of sports can be tracked, and the most important activities such as running are automatically detected by the ring.

Swimming

It is also waterproof up to a pressure of 10 ATM, so the fitness ring can easily be worn while swimming.

Weight

With a weight of around 4.6 grams, it is also lighter than the previous model, so it disturbs the finger less.

Location Tracking

In the app, the GPS coordinates of the last location of the Oura Ring are visible. So if it gets lost, you have a rough geographical area in which to search for it. Winding up via Bluetooth, light, or sound signals is not possible. So if the fitness ring slips into the sofa cushions, for example, the search can take longer.

According to the manufacturer, the battery capacity has been increased. Battery performance partly depends on the ring size, simply because the space for the battery is larger or smaller. The test device was checked in ring size 10 and reached a runtime of around 7 days. This is not exceptional, but good.

Charging Time

Oura specifies the charging time as 1 hour 19 minutes. A practical charging case for on the go is not available; included in the scope of delivery is a charger with a USB-C cable.

Pricing and Variants

The Oura Ring 4 is available in six colour and material variants. The version in black costs around 400 euros, while the smart ring in gold is around 550 euros. The Oura Ring is therefore one of the most expensive models in testing, roughly at the level of the Samsung Galaxy Ring. The price-performance ratio is nevertheless acceptable.

The independent test centre evaluates smart rings under laboratory conditions. The battery life measurement gives the runtime in days that the smart ring's battery achieved in testing. Additional metrics include weight, mean step count accuracy, and measurement variations.

The Oura Ring 4 is positioned alongside the value pick (Newgen Medicals ZX-5545), the price alternative (Amazfit Helio Ring), the top alternative (RingConn Gen 2 Smart Ring), and the budget pick (Newgen Medicals ZX-5687).

Newgen Medicals ZX-5545

The Newgen Medicals Fitness Ring ZX-5545 is cheap, but shows some limitations in testing. It is practical that the smart ring also offers touch control. Five ring sizes are offered, but the manufacturer does without a sizing kit.

Amazfit Helio Ring

The Amazfit Helio Ring is comparatively cheap and nevertheless convinces in testing with its overall performance. There is no sizing kit for finding the right size, and the offering is also limited to only three ring sizes. The equipment is satisfactory, the sleep analysis is acceptable but could be more precise.

RingConn Gen 2 Smart Ring

The RingConn Gen 2 convinces in testing with its outstanding equipment. With a total of 9 ring sizes, the smart ring offers an excellent selection. A sizing kit is available for determining the right size. The sensors enable excellent monitoring of body functions, and the sleep analysis also convinces. A storage box with charging function is included in the scope of delivery.

Newgen Medicals ZX-5687

The Newgen Medicals Fitness Ring ZX-5687 has an extremely low price, but disturbing factors emerge in testing — among other things, the edges of the ring are clearly noticeable. The usual sensors are on board, but the functions are clearly limited. When buying, there is a choice between five ring sizes, but a sizing kit is not offered. And the charging case must be purchased separately.