The Oura Ring 5 is a smaller, slimmer ring with a slightly longer rated battery life, and it costs $50 more than the Oura Ring 4 in the base finishes. Both rings have the same four sensors, use the same app and need the same membership. By mid-September 2026, no independent study had shown the Ring 5 to be more accurate than the Ring 4 for sleep and readiness tracking. Choose the Ring 5 if a thinner ring on your finger is worth $50 to you. Choose the Ring 4 if you want to save the money or if your ring size is below 6 or above 13, because the Ring 5 is not made in those sizes.
How the Oura Ring 5 and Ring 4 differ in size, battery and price
| Oura Ring 5 | Oura Ring 4 | |
|---|---|---|
| Price in the US | $399 (Silver, Black), $499 (Gold, Stealth, Brushed Silver, Deep Rose) | From $349 |
| Width of the band | 6.09 mm | 7.90 mm |
| Thickness | 2.28 mm | 2.88 mm |
| Weight | From 2 grams, depending on size | 3.3 to 5.2 grams, depending on size |
| Sizes | 6 to 13 | 4 to 15 |
| Battery | Up to 6 to 9 days | 5 to 8 days |
| Water | Waterproof to 100 meters, IP68 | Water resistant to 100 meters |
| Sensors | Red, green and infrared LEDs, a digital temperature sensor and an accelerometer on both | |
| Membership | $5.99 a month or $69.99 a year on both | |
Prices are Oura’s list prices in US dollars. The Ring 5 prices are the ones Oura set at launch in May 2026. Battery life on both rings depends on ring size and usage.
The Oura Ring 5 is about 21 percent thinner and 23 percent narrower than the Ring 4
Oura calls the Ring 5 the world’s smallest smart ring and says in the launch post of May 28, 2026, that it is “40% smaller than Oura Ring 4.” On its product page, Oura puts it as “40% Thinner. Lighter. Smaller.”
The ring is not 40 percent thinner. Oura’s own specifications give a thickness of 2.28 mm for the Ring 5 and 2.88 mm for the Ring 4, which makes the new ring about 21 percent thinner. The band is also narrower, 6.09 mm against 7.90 mm, or about 23 percent. Width and thickness together come close to 40 percent: the Ring 5’s band has a cross-section about 39 percent smaller than the Ring 4’s, 13.9 square millimeters against 22.8.
Oura lists the Ring 5 from 2 grams and the Ring 4 at 3.3 to 5.2 grams.
Is the Oura Ring 5 more accurate than the Ring 4 for sleep tracking?
By mid-September 2026, no independent study had shown that it is. On paper the sensor list is identical. Both product pages list red and infrared LEDs for blood oxygen, green and infrared LEDs that alternate to measure heart rate, heart rate variability and respiration rate, a digital temperature sensor and an accelerometer. Sleep stages are estimated from those signals, as explained in our guide to how smart rings track sleep, and so is the Readiness score.
The changes are in how the sensors meet the skin. Oura says the Ring 5 has low-profile sensor domes for better skin contact, more powerful LEDs and “twelve stronger signal pathways,” and it calls the result its most accurate ring.
The accuracy figures on the Ring 5 product page lean on older work. The page lists 95 percent sleep staging accuracy compared with a clinical sleep lab. Its footnote cites a 2021 study co-written by an Oura employee and an Oura adviser, five years before the Ring 5 went on sale. The 95 percent figure refers to telling sleep from wake. When the same study sorted the night into light sleep, deep sleep, REM sleep and wake, its best model reached 79 percent.
The Ring 4 has a longer record. In an independent 2025 study of 13 healthy adults, the Ring 4 agreed with an ECG reference on overnight HRV better than the four other wearables tested. Our Oura Ring 4 review covers what that means in daily use. For someone buying a ring mainly for sleep and readiness, that makes the Ring 4 the better documented of the two for now.
The new software does not set the rings apart either. Alongside the Ring 5, Oura announced GLP-1 Insights and Health Radar, which includes Blood Pressure Signals and Nighttime Breathing. Oura released the new software for the Oura Ring Gen3 and later, so a Ring 4 gets it too.
Battery life and water resistance favor the Ring 5
Oura says one charge of the Ring 5 lasts “up to 6-9 days,” and it rates the Ring 4 for 5 to 8 days, in both cases depending on ring size and usage. That is a day or so more between charges, from a smaller ring.
The Ring 5 is rated waterproof to 100 meters and IP68 for water and dust. The Ring 4 is rated water resistant to 100 meters. Oura also says a new coating makes the Ring 5 its most scratch-resistant ring so far, while the Ring 4 page notes that minor scratches from regular wear are normal.
Charging takes about 80 minutes on the Ring 5 and 20 to 80 minutes on the Ring 4, depending on battery level. The Ring 5 also works with a separate $99 charging case that gives a full day of battery in 10 minutes.
The Ring 5 costs $50 more and the membership is the same
The base Ring 5 in Silver or Black costs $399, and the Ring 4 starts at $349. Both need the Oura membership at $5.99 a month or $69.99 a year for the detailed sleep, readiness and activity data. Because the membership costs the same, the gap stays at $50 however long you keep the ring. Over three years with the annual plan, a base Ring 5 comes to about $609 and a Ring 4 to about $559, as worked out in our breakdown of what a smart ring subscription costs.
The four premium Ring 5 finishes cost $499, $150 more than the cheapest Ring 4. If you find the Ring 4 below its list price, the gap grows by the size of the discount.
Owners who already have a Ring 4 can pair a Ring 5 to the same account and switch between them at no extra cost.
Oura Ring 5 and Ring 4 sizes: which ring fits your finger
The Ring 5 comes in sizes 6 to 13. The Ring 4 runs from 4 to 15. If your finger measures 4, 5, 14 or 15 on Oura’s scale, the Ring 4 is the only one of the two that fits.
A size number may not carry over between the generations. Oura recommends that every Ring 5 buyer use the Ring 5 sizing kit, including people who already own an Oura ring, because the smaller ring may feel different at the same size. Wear the sizer for a day or two, since fingers swell and shrink with temperature and time of day. The same advice applies to other rings, as our Ultrahuman Ring Air sizing guide explains.
Buy the Ring 5 for the smaller band and the Ring 4 to save money
Buy the Ring 5 if comfort on your finger matters most to you. The thinner, narrower band, the IP68 rating and the extra day or so of battery are hardware gains, and in the base finishes they cost $50.
Buy the Ring 4 if you would rather keep the $50. It has the same sensors and the same app features, and its overnight HRV has been tested independently, which the Ring 5’s had not been by mid-September 2026. It is also the only choice if your size is outside 6 to 13.
If you are still deciding whether Oura is the right brand, our roundup of the best smart rings compares it with rings that need no membership, and Whoop vs Oura covers the main alternative that is not a ring.
Last updated: September 2026. Kracked is editorially independent and not affiliated with the brands mentioned. The wellness features described here cannot provide a medical diagnosis; consult a healthcare professional for medical concerns.
Last fact-checked: 14 October 2026