Oura/Nina Raemont/ZDNETFollow ZDNET: Add us as a preferred source on Google.Oura's next big smart ring is its smallest yet. The company unveiled its Oura Ring 5 on Thursday, and the smart ring maker completely redesigned this fifth-gen device to be smaller, thinner, and more comfortable than its predecessors. Starting at $399, the Oura Ring 5 is $50 more than the Ring 4 but comes with some worthwhile upgrades. Also: Whoop vs. Fitbit Air: I've tested both trackers for health and fitness, and this model winsThe Ring 5 arrives two years after the company unveiled its Oura Ring 4, a capable but chunky smart ring. Ring 5 is 40% smaller than Ring 4 -- taking up less space around the finger and delivering a more comfortable fit. But is it worth the upgrade? I break down why you'd want to opt for Oura Ring 5 or stick with Oura Ring 4. Specifications Oura Ring 5Oura Ring 4Battery Six to nine daysFive to eight days Colors availableSilver, Black, Gold (new shade), Stealth, Brushed Silver, and Deep Rose (new shade)Silver, Black, Stealth, Gold, Brushed Silver, Rose GoldMaterialTitanium with vaporized coating for durability TitaniumDimensions 6.09 mm wide and 2.28 mm thick7.99 mm wide and 2.88 mm thickWeight2 - 2.69 g (depending on size)3.3 - 5.2g (depending on size)SizesSix to 13Four to 15IP RatingIP68Water resistant up to 100m PriceStarting at $399Starting at $349 You should buy the Oura Ring 5 if... Oura/ZDNET 1. You want a thinner, inconspicuous ring It fills me with great joy to write that the Oura Ring is finally getting smaller. I've loved the Oura Ring for years, but it has always felt like a piece of technology first and an accessory second. Its chunky design is conspicuous around my finger. Oura is moving away from the chunk with its Ring 5. This fifth-gen ring is 40% smaller than the Ring 4. It's significantly thinner, nearly indistinguishable from a wedding band. This new design could make it feel less visible on your finger and lighter to wear for days and weeks. The Oura Ring 5 could be the first smart ring to actually blend in with other jewelry on the finger and finally be appealing to those who have shied away from smart rings because of their thicker form factors. 2. You want a longer battery Oura extends the Ring 5's battery life by a day. The Ring 4 lasted around five to eight days per charge, whereas the Ring 5 lasts six to nine days per charge. Oura users have experienced battery issues with the Ring 4, as I've previously reported on. Oura VP of Product, Maz Brumand, says the company re-engineered the fifth-generation smart ring to boost its battery life on this smaller device. Also: The best smart rings of 2026: I tested and found an obvious winnerThis included adding more powerful LEDs for biometric measurements, adding a new battery to the smart ring, and refining the algorithm for greater efficiency. I'll see whether these edits pay off in the Oura Ring 5 once I test it out for myself. 3. You want a more durable smart ring Unlike the Oura Ring 4, the Oura Ring 5 features a scratch-resistant vapor deposition coating. Oura calls it its most scratch-resistant ring yet, though we'll be the judge of that once we get our hands on it. The new ring's IP rating has been upgraded to IP68. You should buy the Oura Ring 4 if... Nina Raemont/ZDNET 1. You have a smaller (or larger) ring size The Oura Ring 4 offers an expansive selection of sizes compared to the Ring 5, which is limited to size six through 13. Oura Ring 4 is available for sizes four through 15. 2. You care more about the software features (and savings)The Oura Ring 5 has a higher starting price of $399, $50 more expensive than the Ring 4. You'll pay even more if you opt for the premium finishes, which include Deep Rose, Stealth, and Gold, priced at $499 each. And don't forget about that $70 annual subscription that unlocks the bulk of your Oura Ring data. The Ring 4, while not as slim and light, gets the same software updates as Ring 5. These include a few fresh new additions to the smart ring's capabilities, such as a Health Radar feature that monitors key health patterns, including nighttime breathing and sleep blood pressure. The feature spots deviations in breathing patterns that daytime readings may miss, Oura explains in a press release. The nighttime breathing feature is made possible in partnership with ResMed. If users experience breathing disturbances during sleep, they can complete sleep assessments and connect with ResMed providers for diagnosis and treatment. Also: Why your Oura Ring battery is dying quicker (and what Oura is doing about it)That's not the only connected care partnership Oura introduces with the Ring 5. Oura also announced a partnership with Counsel Health that will bring medical AI tools to the app. In a huge leap for the company, the AI tool can be used for clinical questions, alongside your run-of-the-mill wellness inquiries you'd ask a chatbot. Oura users can now connect with Counsel physicians to receive medical care. Lastly, Oura introduced a GLP-1 Insights feature that tracks a user's biometrics throughout their journey using the weight-loss drug. The feature combines details like dosing, side-effect tracking, weight, and overall biometrics to contextualize a user's experience with the novel drug. As you can see, there are lots of software upgrades the Ring 4 won't skip out on, so you don't need to upgrade to the Ring 5 for these new features - only for the new design and longer battery. Writer's choiceWhile I have yet to test the Ring 5, I'm seriously excited to try it out because of its novel design, which is a significantly new addition to this smart ring market. I have loved my Oura Ring 4, however, and have little issues with it. Sure, it's a bit clunky around the finger. But it delivers wonderful health insights, a fair battery life, and more comfort than a wrist-worn wearable.