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Use the sizing kit made for the Oura Ring generation you plan to buy, then wear your best-fitting sizer for at least 24 hours—including overnight. Try it on several fingers and choose a fit that stays snug at the base without causing pressure or pain. Oura does not offer half sizes, and its sizes vary by generation, so a size from another ring is not a reliable substitute.
Start with a sizing kit for your Oura Ring generation
Oura sizes differ slightly from standard US ring sizes, and sizing differs between Oura generations. Use the sizing kit for your Oura Ring generation; do not assume a jewelry ring or a different-generation Oura ring will fit the same.
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Oura’s guide, last updated August 10, 2026, lists sizers in sizes 4–15 for Oura Ring 4 and sizes 6–13 for Oura Ring 5. Those ranges apply to those generations only.
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Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Oura says individual sizing kits are not sold through its online store. A complimentary kit is included if you choose “Size Later” when ordering a ring from Oura. Many authorized retailers sell kits separately, and some may apply the kit purchase toward a later ring purchase from that retailer. Availability and terms vary by seller and region. Some retailers, including Best Buy and Target, offer in-person sizing; Amazon is an example where a kit credit may appear as a coupon code. Check the current seller and offer before buying.
#1 Best Overall
- SIZE BEFORE YOU BUY - It’s important to size yourself using our Oura Ring 5 Sizing Kit before purchasing an Oura Ring 5. Oura Ring 5 sizes are different from standard ring sizes and Oura Ring 4 sizes
- AVAILABLE SIZES - Oura Ring 5 is available in sizes 6-13. There are no half sizes
- CHOOSE A FINGER - Oura Ring 5 works on all fingers and can be worn on either hand. For optimal accuracy, we recommend wearing your Oura Ring 5 on your index, middle, or ring finger. Size the exact finger you plan to wear your Oura Ring on
- CHOOSE A FINGER - Oura Ring 5 works on all fingers and can be worn on either hand. For optimal accuracy, we recommend wearing your Oura Ring 5 on your index, middle, or ring finger. Size the exact finger you plan to wear your Oura Ring on
- COMFORT AND ACCURACY - A properly fitting Oura Ring 5 will result in the highest data accuracy, comfort, and overall experience
Try several fingers, then wear the sizer for a full day
Oura says any finger can work, but recommends the index finger for best accuracy. Its FAQ also identifies the middle and ring fingers as good options for signal quality. Try more than one finger and compare both hands: the best choice is the finger where the sizer stays securely at the base without an uncomfortable struggle over the knuckle. If the knuckle is much wider than the finger base and makes the fit unreliable, test another finger.
- Put on the leading candidate sizer and check that it rests securely at the base of your finger.
- Wear it for at least 24 hours, including while you sleep. Finger size changes during the day and night, so an immediate try-on cannot show how the fit will feel across ordinary conditions.
- Check the fit during normal activity and after waking. Make a fist: a gap at the top is a sign to try a smaller size.
Choose snug and secure, not tight
Oura’s Member Care FAQ describes a proper fit as “snug but comfortable—not too tight or too loose.” The ring should sit securely at the base and maintain skin contact. Oura says close sensor contact supports consistent data, but its published guidance does not quantify the effect of fit on measurement accuracy.
Rank #2
- OURA RING 4 SIZING KIT - The Oura Ring 4 Sizing Kit is the ideal way to find the perfect size. It’s a custom sizer that allows for you, and those around you, to find the perfect fit before purchasing
- SIZE BEFORE YOU BUY - Oura Ring 4 sizes are different from standard ring sizes. Size yourself with the Oura Ring 4 Sizing Kit. For additional details, see “From the brand” section below
- NOT STANDARD SIZING - Oura Ring 4 sizes are slightly different from standard ring sizes, so it is important to size yourself using our Oura Ring 4 Sizing Kit. Oura Ring 4 is available in sizes 4-15. There are no half sizes
- COMFORT AND ACCURACY - A properly fitting Oura Ring will result in the highest data accuracy, comfort, and overall experience
- CHOOSE A FINGER - Oura Ring 4 works on all fingers and can be worn on either hand. For optimal accuracy, we recommend wearing your Oura Ring 4 on your index, middle, or ring finger. Size the exact finger you plan to wear your Oura Ring 4 on
If you are between sizes, Oura recommends the smaller size for a more secure fit and closer sensor contact, as long as it remains comfortable. Plastic sizers can feel stickier than the finished ring, so account for that difference—but do not dismiss ongoing discomfort.
- Good signs: the sizer sits securely at the base, maintains contact, and does not feel restrictive.
- Try another size or finger: the sizer leaves a gap when you make a fist or is difficult to get over your knuckle.
- Do not accept the fit: it causes ongoing pressure, pain, numbness, pinching, or marks that do not fade shortly after removal.
Confirm orientation and complete your order
Once you have chosen a size, orient the ring according to its model. Oura’s FAQ says Ring 5, Ring 4, and Gen3 Horizon should be worn with the dimple facing the palm side. Gen3 Heritage should be worn with its flat side on top.
Rank #3
- GIVE THE GIFT OF OURA RING 5 - This gifting kit takes the guesswork out of gifting, allowing the recipient to purchase the correct size and preferred finish of their Oura Ring 5 (Gift card sold separately)
- A FEW EASY STEPS - Purchase the gifting kit and an Amazon gift card with your desired value. Your friend or loved one will size themselves, and then purchase their Oura Ring 5 using the gift card
- WEAR TEST - Fingers expand and contract based on environmental factors, so we recommend wearing the ring sizer for 24 hours to confirm your best fit. The sizer ring should not rotate as you go about normal daily tasks
Follow the size-confirmation instructions for the purchase channel. Oura says customers ordering through its online store confirm their size through My Orders. If you bought a sizing kit from an authorized retailer, return to that retailer to purchase the ring.
Quick Recap
Best Value
- GIVE THE GIFT OF OURA RING 4 - This gifting kit takes the guesswork out of gifting, allowing the recipient to purchase the correct size and preferred finish of their Oura Ring 4. Gift card sold separately.
- A FEW EASY STEPS - Purchase the gifting kit and a gift card with your desired value. Your friend or loved one will size themselves, and then purchase their Oura Ring 4 using the gift card.
- CHOOSE A FINGER - Oura Ring 4 works on all fingers. Make sure to size the finger you plan to wear your Oura Ring on. For optimal performance and accuracy, we recommend wearing your Oura Ring on your index, middle, or ring finger.
- FIND YOUR FIT - Oura Ring 4 should fit snug around the base of your finger, but not to the point where it’s uncomfortable. When sizing yourself, the ring must fit over the largest part of your finger, like your knuckle.
- WEAR TEST - Your fingers expand and contract based on environmental factors, so we recommend wearing your ring sizer for 24 hours to confirm your best fit. Your ring should not rotate as you go about normal daily tasks.
Rank #4
- OURA RING GEN3 SIZING KIT - The Oura Ring Gen3 Sizing Kit is the ideal way to find the perfect size. It’s a custom sizer that allows for you, and those around you, to find the ideal fit before purchasing
- SIZE BEFORE YOU BUY – Size with Gen3 Sizing Kit prior to purchasing Oura Ring Gen3 (different sizing from Oura Ring 4). For additional details, see “From the brand” section below.
- NOT STANDARD SIZING — Oura Ring Gen3 Sizing Kit only works to size for Oura Ring Gen3. Gen3 sizes are different from standard ring sizes. Oura Ring Gen3 is available in sizes 6-13. There are no half sizes.
- HOW IT SHOULD FIT - We recommend wearing your ring sizer for at least 24 hours to confirm your best fit. Oura Ring Gen3 should fit securely and comfortably at the base of your finger. Your ring should not rotate as you go about normal daily tasks.
- COMFORT AND ACCURACY — A properly fitting Oura Ring Gen3 will result in the highest data accuracy, comfort, and overall experience
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.
