The Oura Ring 4 features slimmer sensors, higher accuracy and more sizes

Oura is fundamentally overhauling its popular smart ring and app. The company just announced the Oura Ring 4 for $349, which will feature a slimmer design, improved accuracy, and more sizes. Starting today, the Oura app is also being completely redesigned to better organize the numerous new features that have been introduced in recent months.

At first glance, the Oura Ring 4 isn't all that different from the Gen 3. However, the new ring will be made entirely of titanium. (The previous ring had an epoxy interior.) All rings will also be completely round, like the current Horizon models, with no flat edge. Perhaps most notably, the sensors no longer have protruding dome-shaped covers. Instead, they are recessed to create a flatter and more comfortable profile.

The bigger update, however, comes from the software. Oura says its new algorithm helps solve a big problem with smart rings – the fact that every finger is different and smart rings can get out of alignment throughout the day. This can result in sensors not retrieving data from the optimal location, leading to data gaps. To solve this problem, the new algorithm increases the number of signal paths from eight to 18. This supposedly allows it to select which signal is the best at a given time.

Citing an outside study, Oura says the new algorithm results in a 120 percent increase in signal quality and a 30 percent improvement in accuracy in blood oxygen tracking. The new algorithm is also claimed to reduce the gaps in daytime and nighttime heart rate measurements by 7 and 31 percent, respectively. In addition to better accuracy, the company says the new algorithm also improves battery life up to eight days, depending on the size of the ring. (For smart rings, larger sizes tend to have longer battery life.) Of course, these are claims from controlled studies and testing scenarios. We have to see how they can be implemented in practice.

It's worth noting that Oura is also expanding its size range. You can now buy the ring in sizes 4 to 15. Previously, the smart ring was limited to sizes 6 to 13. This is partly because the demographic has now become majority female, with women in their 20s the fastest-growing segment, according to Oura. Overall, expanding the size range is a good thing.

As for the app, Oura users may have noticed that it has become increasingly cluttered in recent months as the company has added new features for stress tracking, reproductive health, heart health, and an experimental Labs beta program. To combat this, the redesigned app will now have three sections: Today, Vitals and My Health. The Today tab is a dynamic summary of your biometric data depending on the time and a user's health goals. Vitals allows members to dive deeper into metrics and results, while the My Health tab focuses on longer-term trends.

In addition to the redesign, Oura is also introducing a revised daily stress metric. It also adds automatic activity detection for 40 different activity types. For reproductive health, Oura also adds fertile window predictions for people trying to conceive. It underlined that the function is there not It is intended to be used as a contraceptive and notes its partnership with Natural Cycles for people who wish to do so. Finally, Oura says it's finally bringing its Labs program to Android.

The Oura Ring 4 starts at $349, is HSA and FSA eligible, and will begin shipping October 15th. People may be unhappy to hear that the starting price is being increased by $50, but Oura Ring Gen 3 devices will continue to be available until inventory runs out. Oura also confirmed that its $6 per month or $70 per year subscription will not be increasing.