There is a reason doctors put the sensor on a finger, not the wrist, when measuring blood oxygen saturation. Fingers yield stronger, clearer biosignals through the arteries.
Brian Lynch, executive vice president of hardware engineering at Oura, explained the strengths of ring-type wearables this way at a press briefing held on the 18th at the Lotte World Tower SKY31 Convention in Songpa-gu, Seoul.
Founded in Finland and headquartered in San Francisco, Oura is the leading player in the smart ring market, having raised more than $900 million (about 1.25 trillion won) in October last year and been valued at $11 billion (about 15 trillion won). According to market research firm Omdia, it accounted for 74% of global smart ring shipments in the first half of 2025, and 2025 revenue reached $1 billion (about 1.4 trillion won). Oura will launch its new product, "Oura Ring 5," in Korea on the 25th.
◇ Learning the body's "baseline state" with finger data
According to Oura, pulse signals captured from the fingers are up to 100 times stronger than at the wrist. If users wear the ring an average of 23 hours a day, it can analyze how heart rate and heart rate variability (HRV), sleep, and stress change over long periods. Lynch said, "Early wearables were reactive products that told you what happened the day before," and added, "The future of health management lies in preventive approaches that detect changes in the body early and help users take action."
The Oura Ring analyzes sleep by combining body temperature, photoplethysmography (PPG), and movement. Instead of a uniform average, it compares readings with the user's usual metrics and shows readiness, sleep, and activity scores. After detecting changes in the body, it suggests whether to increase exercise or focus on recovery. Lynch said, "Oura has invested for more than 12 years in technology that analyzes sleep and provides useful information," and added, "Our goal is to combine all available signals—such as temperature, PPG, and movement—to achieve performance close to a polysomnography test at a medical institution."
Women's health features use the same principle. Changes in body temperature and resting heart rate are used to analyze menstrual cycles and suggest adjustments to sleep, nutrition, and activity by cycle. It also tracks changes related to hormonal contraception, pregnancy, and menopause. The pregnancy feature compares a user's biometrics with Oura's dataset of more than 10,000 pregnancy cases. George Abbott, who oversees Europe, the Middle East, and Africa and the Asia-Pacific at Oura, said, "Existing pregnancy management services focus on fetal growth, but information about the pregnant person's own bodily changes is lacking," adding, "Women's health has long been under-addressed in science and medicine."
◇ Fewer sensor paths while maintaining measurement performance
The new model is about 40% smaller than its predecessor. The number of sensor signal paths was reduced by 6, from 18 to 12 (about 33%). Although the sensor paths were reduced, the product uses light-emitting diodes (LEDs) with four times the output and places the thinned inner ring sensors closer to the skin. The company said it maintained the same measurement quality as before by using a new algorithm. Lynch said, "Reducing sensor channels while greatly shrinking the product size was a concern even among our internal engineers," adding, "We compensated with more powerful LEDs, sensors closer to the skin, and more efficient algorithms."
The size reduction is also related to data continuity. If a product is uncomfortable and often taken off, long-term data will have gaps. Lynch said, "Members wanted a smaller ring while using the same health information," and added, "To avoid sacrificing functionality and battery performance, we redesigned the mechanical and electrical architecture from scratch." The battery lasts up to 7 days on a single charge.
◇ "The app and health insights matter more than the hardware"
The domestic price of the Oura Ring 5 ranges from 630,000 to 780,000 won depending on color. A separate monthly subscription fee of 9,400 won is also required. Oura defines the smart ring not as a one-off device sale but as a subscription business that provides health information by analyzing biometric data accumulated over time. Abbott said, "We have no plans to change the subscription model in Korea," adding, "You buy the hardware, but the real value lies in the data analysis and health insights provided by the app." In response to criticism that the subscription fee could be a barrier to entry, he said, "We now have the interesting task of explaining the need for and value of the subscription model to Korean consumers."
According to Oura, more than 80% of members who used the product for a year continued their paid subscriptions afterward. For 51% of all members, recommendations from family or friends were their first exposure to the product. Abbott said, "Given the high subscription retention and users recommending the product to those around them, we are confident in our current business model."
The company also said the subscription business is related to privacy protection. Abbott said, "Privacy and security are not negotiable," adding, "Because we have subscription revenue, we are not pressured to sell data, and we can manage member information safely."
Most core features of the Oura app are available in Korea, but integration with continuous glucose monitors (CGM) is excluded. Abbott said, "We have not yet secured a CGM partner to collaborate with in Korea," adding, "We provide services in consideration of country-specific regulations, but the rest of the core app features are available in Korea."
There are currently no finalized bundles combined with Naver Membership or mobile carrier plans. However, the company will consider introducing them depending on market conditions after reviewing proposals from domestic partners. There are also no immediate plans to establish a Korean entity or office. Customer support is provided through a Korean-language call center operated by a local partner and 34 offline service locations. However, the company did not disclose specific after-sales service (AS) procedures such as repairs and exchanges.