Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsOura Ring 5 uses sizes 6–13, while Oura Ring 4 uses sizes 4–15, and Oura says the generations are sized slightly differently. Use the sizing kit for the exact generation you plan to buy; neither a Ring 4 size nor a standard U.S. ring size is guaranteed to transfer. Wear the sizer for at least 24 hours, including sleep, before choosing.
Oura Ring sizes at a glance
| Model | Available sizes | Kit to use |
|---|---|---|
| Oura Ring 5 | 6–13 | Ring 5 sizing kit |
| Oura Ring 4 | 4–15 | Ring 4 sizing kit |
| Earlier generations | Check the specific model | Verify generation compatibility before buying |
Oura uses whole sizes, not half sizes, and says its sizes differ slightly from standard U.S. ring sizes. A conventional ring-size chart or existing ring is only a rough starting point; use the generation-matched Oura sizer to choose.
See Oura’s official size-selection guidance before ordering.
Which Oura sizing kit do you need?
For Oura Ring 5: sizes 6 through 13
Use the kit labeled for Ring 5. Oura lists Ring 5 in whole sizes 6–13 and says its sizing differs slightly from Ring 4. Do not use a Ring 4 size number as a guaranteed match.
Recommended Free Tools
#1 Best Overall
- 【Check the Size Before Purchase】 Before buying the BIEMHA Smart Ring, we strongly suggest that you refer to the size chart and carefully measure the circumference of your finger. This will ensure you get the most comfortable wearing experience and easily avoid any unnecessary returns or exchanges.
- 【Real‑time Accurate Sleep & Fitness Monitoring】 BIEMHA smart ring tracks your sleep quality and daily activities in real time. With advanced sensors, it provides precise data about your sleep cycle, helping you optimize rest and recovery. Whether you are tracking steps, calories or exercise performance, this smart ring can provide you with the most accurate insights to support your fitness goals and enhance your overall health.It is a good choice for family and friends.
- 【Health Monitoring】The BIEMHA ring features advanced 4.0 sensors that automatically measure your heart rate every 30 min when worn. It provides continuous health tracking and comprehensive wellness management all day.
- 【2‑3 Day Battery Life】 With a 2‑3 day battery life, the BIEMHA smart ring ensures continuous health monitoring without frequent charging. When used with the smart charging case, the usage time can even exceed 5 days. Whether you are tracking sleep patterns or fitness activities, you can count on long‑lasting performance without constant interruptions.
- 【80‑meter Waterproof, Suitable for Various Scenarios】 The BIEMHA Smart Ring has excellent waterproof performance, with a waterproof depth of up to 80 meters. Whether it's for daily wear, an intense workout session or a pleasant swimming time, it can handle it with ease. What's more, even if you have sensitive skin, you can still enjoy an extremely comfortable wearing experience when wearing this ring.
For Oura Ring 4: sizes 4 through 15
Use the kit labeled for Ring 4. It covers whole sizes 4–15. Oura lists Ring 4 at 7.9 mm wide and approximately 2.88 mm thick; Ring 5 is 6.09 mm wide and 2.28 mm thick. These are product dimensions, not a size-conversion chart.
Oura’s Ring 5 specifications and Ring 4 specifications provide model details.
Buying an older Oura generation
If you are buying an earlier-generation ring, confirm its model and the compatible sizer before relying on a size from another generation. Oura’s current guidance emphasizes using the kit labeled for the ring you intend to buy.
How to test an Oura Ring size correctly
- Use the generation-matched sizer. Oura says the plastic sizers have the same width and circumference as the ring, but differ in feel and weight.
- Try suitable fingers on both hands. Oura recommends the index finger for best accuracy; the middle or ring finger can also work. Avoid a finger whose knuckle is much wider than its base.
- Wear the sizer for at least 24 hours, including sleep. As Oura Member Care puts it, “Fingers change size throughout the day and night.”
- Check the fit at the base of your finger. It should feel snug, not tight, and sit securely. Make a fist; if there is a visible gap between the ring and the top of your finger, try a smaller size.
- If between sizes, follow Oura’s recommendation to try the smaller size. Choose it only if the fit remains comfortable and secure.
What a good Oura Ring fit feels like
Oura’s guidance is to seek a snug, comfortable fit that sits securely. Try the sizer during normal activity and overnight rather than relying on a brief try-on. If the fit is uncomfortable, test another size or suitable finger.
Rank #2
- THE WORLD’S SMALLEST SMART RING - 40% smaller than the previous generation, Oura Ring 5 is thinner, lighter and smaller than ever. The updated all-titanium design is more scratch-resistant and comfortable than ever
- SIZING IS ESSENTIAL - Oura Ring 5 uses unique sizing different from standard jewelry rings and other Oura Ring generations; use the Oura Ring 5 Sizing Kit to find your perfect fit before purchasing
- EVERYDAY HEALTH SENSING - Oura tracks over 50 health metrics, including sleep, activity, stress, heart health, metabolic health and women’s health metrics. Oura seamlessly integrates with over 40 apps including Natural Cycles, Strava, & more
- OURA MEMBERSHIP - First month of membership is included with purchase, for new members only. Subscription is 5.99/mo afterwards. Membership is tied to your account via the Oura App, not your physical ring
- REBUILT FOR GREATER ACCURACY - Oura Ring 5 has been re-engineered and reconfigured, providing more precise personal health data. Larger, smarter sensors bring research-grade accuracy—all in Oura’s smallest form factor yet
What if you are between Oura sizes?
Oura recommends the smaller size when you are between sizes, citing closer sensor contact and the smoother feel of the finished ring compared with its plastic sizer. This is Oura’s guidance, not a guarantee that the smaller size will suit everyone.
- Try the smaller size if it feels snug and comfortable during the full test.
- Try the larger size or another finger if the smaller sizer feels too tight or uncomfortable.
- Re-test both sizes through a full day and night if you are unsure.
Why your normal ring size may not match Oura
Oura says its sizes differ slightly from standard U.S. ring sizes and does not offer half sizes. Existing jewelry may provide a rough starting point, but it is not a reliable substitute for the sizing kit made for your Oura generation.
Ring 5 versus Ring 4: why the generation matters
| Characteristic | Oura Ring 5 | Oura Ring 4 |
|---|---|---|
| Whole-size range | 6–13 | 4–15 |
| Width | 6.09 mm | 7.9 mm |
| Thickness | 2.28 mm | Approximately 2.88 mm |
| Kit to use | Ring 5 kit | Ring 4 kit |
Oura says the generations size slightly differently. Compare the size ranges and physical dimensions, but do not treat a matching number as proof of an equivalent fit.
How Oura sizing kits and orders work
Oura says it does not sell individual sizing kits through its own online store. A complimentary kit is included with the “Size Later” purchase option; after sizing, confirm your selected size in My Orders. Retailer purchases follow the retailer’s process.
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchPC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Rank #3
- 【Check the Size Before Purchase】 Before buying the BIEMHA Smart Ring, we strongly suggest that you refer to the size chart and carefully measure the circumference of your finger. This will ensure you get the most comfortable wearing experience and easily avoid any unnecessary returns or exchanges.
- 【Real‑time Accurate Sleep & Fitness Monitoring】 BIEMHA smart ring tracks your sleep quality and daily activities in real time. With advanced sensors, it provides precise data about your sleep cycle, helping you optimize rest and recovery. Whether you are tracking steps, calories or exercise performance, this smart ring can provide you with the most accurate insights to support your fitness goals and enhance your overall health.It is a good choice for family and friends.
- 【Health Monitoring】The BIEMHA ring features advanced 4.0 sensors that automatically measure your heart rate every 30 min when worn. It provides continuous health tracking and comprehensive wellness management all day.
- 【2‑3 Day Battery Life】 With a 2‑3 day battery life, the BIEMHA smart ring ensures continuous health monitoring without frequent charging. When used with the smart charging case, the usage time can even exceed 5 days. Whether you are tracking sleep patterns or fitness activities, you can count on long‑lasting performance without constant interruptions.
- 【80‑meter Waterproof, Suitable for Various Scenarios】 The BIEMHA Smart Ring has excellent waterproof performance, with a waterproof depth of up to 80 meters. Whether it's for daily wear, an intense workout session or a pleasant swimming time, it can handle it with ease. What's more, even if you have sensitive skin, you can still enjoy an extremely comfortable wearing experience when wearing this ring.
Many authorized retailers sell sizing kits separately, and Oura says some may credit the kit purchase toward a later ring purchase. Oura’s retail guidance gives Amazon, Best Buy, Costco, and Target as examples of retailer credit arrangements. Availability, eligibility, and terms can vary, so check the current retailer listing and generation label before buying. Oura says a separately purchased kit need not be returned after sizing.
For the direct-order workflow, see Oura’s purchase instructions. Its retail-purchase guidance explains retailer purchases and kit options.
Common Oura sizing mistakes
- Using the wrong generation’s kit: Ring 5 and Ring 4 have different size ranges and Oura says they size slightly differently.
- Relying on a standard ring-size chart: Oura sizes differ slightly from standard U.S. sizes and do not include half sizes.
- Testing for only a few minutes: Wear the sizer for at least 24 hours, including sleep.
- Choosing without checking the fit on a suitable finger: Try the index, middle, or ring finger on both hands and check that the sizer sits securely.
- Assuming the smaller size is always right: Oura recommends it between sizes, but the fit should remain comfortable.
Oura sizing checklist
- Identify whether you plan to buy Ring 5 or Ring 4.
- Confirm the size range: Ring 5 is 6–13; Ring 4 is 4–15.
- Use the kit labeled for that generation.
- Try suitable fingers on both hands.
- Wear the sizer for at least 24 hours, including sleep.
- Check that it feels snug and comfortable and sits securely; make a fist and check for a gap.
- If between sizes, try Oura’s recommended smaller size and confirm it remains comfortable.
- For a direct Oura order, confirm your size in My Orders; for a retailer purchase, follow the retailer’s process.
FAQ
Does Oura Ring 5 fit the same as Ring 4?
Not necessarily. Oura says the generations size slightly differently. Ring 5 uses sizes 6–13 and Ring 4 uses sizes 4–15, so use the kit for the model you plan to buy.
Does Oura make half sizes?
No. Oura uses whole sizes only. If you are between sizes, test the sizers and follow Oura’s recommendation to try the smaller size if it remains comfortable.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Rank #4
- THE WORLD’S SMALLEST SMART RING - 40% smaller than the previous generation, Oura Ring 5 is thinner, lighter and smaller than ever. The updated all-titanium design is more scratch-resistant and comfortable than ever
- SIZING IS ESSENTIAL - Oura Ring 5 uses unique sizing different from standard jewelry rings and other Oura Ring generations; use the Oura Ring 5 Sizing Kit to find your perfect fit before purchasing
- EVERYDAY HEALTH SENSING - Oura tracks over 50 health metrics, including sleep, activity, stress, heart health, metabolic health and women’s health metrics. Oura seamlessly integrates with over 40 apps including Natural Cycles, Strava, & more
- OURA MEMBERSHIP - First month of membership is included with purchase, for new members only. Subscription is 5.99/mo afterwards. Membership is tied to your account via the Oura App, not your physical ring
- REBUILT FOR GREATER ACCURACY - Oura Ring 5 has been re-engineered and reconfigured, providing more precise personal health data. Larger, smarter sensors bring research-grade accuracy—all in Oura’s smallest form factor yet
Which finger is best for an Oura Ring?
Oura recommends the index finger for best accuracy. The middle and ring fingers can also work. Try suitable fingers on both hands and choose a comfortable, secure fit.
How long should I wear the Oura sizing ring?
Wear it for at least 24 hours, including sleep. Oura notes that fingers change size throughout the day and night.
How do I know if my Oura Ring is too tight?
Oura advises seeking a snug, comfortable fit, not a tight one. If the sizer feels uncomfortable, try another size or suitable finger rather than choosing it simply because it is smaller.
The Bottom Line
Use the sizing kit for the exact Oura generation you plan to buy. Ring 5 uses sizes 6–13; Ring 4 uses sizes 4–15, and Oura says the generations size slightly differently. Test the sizer for at least 24 hours, including sleep, and choose a snug, comfortable fit; if between sizes, Oura recommends trying the smaller one.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
