The archive · Product Ideas · Product decision · 2024
Oura Ring 4: recessed sensors make the smart ring flat, comfy, and accurate (2024)
Oura Ring 4 moves its sensor domes inside a fully titanium ring, adds an 18-path sensing system and sizes 4–15 — so tracking disappears into daily wear.
Oura
What it had to solve
Smart rings measure through raised sensor bumps that dig into fingers, and rings shift out of alignment during the day, leaving gaps in the data. Oura wanted a device comfortable enough to wear 24/7 — 'like wearing a t-shirt' — while measuring more accurately.
How it works
On October 3, 2024, Oura launched the $349 Oura Ring 4, a fourth-generation smart ring built around 'Smart Sensing,' a platform that adapts to each wearer's physiology. The most visible change is on the inside: the raised sensor domes of earlier rings are gone, replaced by recessed sensors in a fully titanium ring.
Oura's design team described the goal as a product that 'disappears into your life' — like wearing a t-shirt. In a Q&A about the making of the ring, the industrial designers explained how, in a device this small, every 0.1 mm affects fit, comfort, and electronics, and how they iterated with prototypes in Helsinki and Oulu. The new ring houses an 18-path multi-wavelength PPG sensing subsystem, comes in sizes 4 to 15, and runs up to eight days per charge.
The company says the redesign raised signal quality by 120% and blood-oxygen tracking accuracy by 30%, while cutting gaps in daytime and nighttime heart-rate readings by 7% and 31%. The Verge reported the slimmer profile, expanded sizing, and redesigned app as the headline changes, noting the new algorithm lets the ring pick whichever signal path is best as fingers swell and the ring shifts.
Why it lands
- Recessing the sensors removed the pinch points that made earlier rings uncomfortable to wear all day.
- More signal paths let the ring adapt to fingers that change size and shift during the day, attacking data gaps at the source.
- Solving comfort and accuracy together meant the redesign wasn't a style tradeoff — it was a sensing upgrade.
- A fully titanium interior addressed skin sensitivity and durability, widening who could wear it 24/7.
What it did
Oura says the redesign improved comfort and accuracy together — citing a 120% increase in signal quality, a 30% bump in blood-oxygen tracking accuracy, and fewer gaps in heart-rate readings — while The Verge noted the flat profile as the generation's most visible change.
What you can take
When a device must be worn constantly, comfort is a sensing problem too: removing the bumps didn't just feel better, it reduced data gaps — design and accuracy were solved together.
Since then
Oura Ring 4 shipped in October 2024 and became the company's flagship, with Oura later adding ceramic finishes and a charging case. The design choices — recessed sensors, expanded sizing, and adaptive signal selection — were widely cited as the template for comfortable continuous sensing, arriving in the same market moment as Samsung's Galaxy Ring and pushing smart rings toward mainstream health wear.
Sources
- Discover the Brand-New Oura Ring 4
- Inside the Ring: The Making of Oura Ring 4
- The Oura Ring 4 has slimmer sensors, increased accuracy, and more sizes
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