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Your complete guide to picking the right size Oura Ring

Choosing the right Oura Ring size is more important than you may realize.
By
November 3, 2023
oura ring 3 smurf hand
Rita El Khoury / Android Authority

Smart rings are unique in the world of fitness trackers. Instead of wrist-worn devices with large displays and flexible straps, smart rings are more rigid bands made for wear on a finger. As a consequence of this design, smart rings usually require a measurement process before purchase, which is no less true with the Oura Ring. The right fit is vital for user comfort and fitness tracking accuracy. Here’s how to choose the right size Oura Ring.

Which finger should I wear my Oura Ring on?

oura ring 3 on hand vs normal ring
Rita El Khoury / Android Authority

Theoretically, you can choose to wear the Oura Ring on any finger, but Oura suggests wearing the third-generation ring on the index finger with the three sensor nubs on the palm side of your hand. A notch on the outside of the ring makes it easy to orientate the device. The index finger should provide the best tracking accuracy, but it’s not always the most comfortable option unless you’re used to wearing rings on that finger.

Our reviewer Rita El Khoury noted that this was the case for her. She constantly felt the Oura Ring’s presence on her index finger but almost forgot about it while placed on her middle finger. If neither digit works for you, you can wear the ring on your ring finger.

How to choose the right size Oura Ring

oura ring 3 sizing kit
Rita El Khoury / Android Authority

Aside from choosing an Oura Ring model, picking the correct size is arguably the most important step in your smart ring purchasing journey.

Ordering an Oura Ring size kit

Before ordering an Oura Ring, you must determine the best size for you. We suggest requesting a Free Sizing Kit in your Oura Ring order to aid your quest. The company will ship out the sizing kit first, allowing you to wear all sizes, pick the best for your circumstance, and confirm the size before your actual ring is delivered.

Alternatively, if you don’t fancy waiting for a sizing kit to arrive and own a 3D printer, you can print your own sizing rings using these official files.

Oura Ring size table

Oura Ring’s sizing kit includes eight plastic rings ranging from size 6 (the smallest) to size 13 (the largest). In our measurements, the rings are roughly the same thickness, falling between 2.5mm and 2.9mm. In terms of height, all eight fall just short of 8mm. However, the critical measurement for fit and feel is internal diameter. You can find the approximate internal dimensions of each ring below.

Oura Ring sizeApprox. inner diameter (incl. sensor bumps)
6
15.2mm
7
16mm
8
16.8mm
9
17.6mm
10
18.4mm
11
19.2mm
12
20mm
13
20.9mm

The above table should be used as a guide, and we don’t recommend using the dimension chart to pick an Oura Ring size. If you don’t have time to wait for a sizing kit, measure the internal diameter of a ring you’re already wearing on your index or ring fingers and choose a similar Oura Ring size. We don’t quite recommend this, though, as nothing quite beats real-world experience. Additionally, a diameter that may seem too tight or loose on paper may give you the perfect fit in practice.

It’s worth noting that Oura does not offer half or custom sizes, nor do the rings conform to standard US sizes. For instance, a US ring size 6 has an inner diameter of 16.5mm, a fair bit larger than the size 6 Oura Ring.

Tips for picking the correct Oura Ring size

oura ring 3 on hand index
Rita El Khoury / Android Authority

Once you’ve printed your sizing rings and received a sizing guide, you can experiment. There are a few important points to remember when choosing an Oura Ring size. We’ve outlined these below.

  • Oura recommends that you pick a finger on which to wear the ring, then choose a size that feels best on that particular finger. However, we believe that testing the sizer rings on a few fingers is a better bet. This more thorough method will give you a better idea of how each ring size feels on multiple fingers and whether wearing it on one digit is more comfortable.
  • If you usually wear other rings on your fingers, don’t remove them. This will give you a better real-world experience of wearing the Oura Ring alongside your usual kit.
  • You should wear a sizer ring for at least 24 hours, taking into account body and temperature changes throughout the day. Wearing the sizers for longer should allow you to make a more informed decision.
  • Go about your normal routine while wearing the sizer rings, whether that includes training, washing dishes, driving, or sleeping.
  • Similarly, the ring must be comfortable to wear for long hours. During our review, the Oura Ring 3 endured around seven days on a single charge.
  • When wearing the sizer rings, ensure that the sensor bumps are positioned on the palm side of your finger.
  • Ideally, the rings should be worn at the base of your finger.
  • Finally, Oura warms that the plastic sizing rings may have a seam due to the mold used, which can cause discomfort for some. The actual titanium Oura Ring doesn’t have this issue.

Return to the company’s site to complete your order when you’ve found the perfect size Oura Ring. Once you’ve received the ring and find it too loose or tight, it’s not the end of the world. Oura allows users one exchange if the ring they received is the wrong size or color.

Notably, the sizing process is one of the downsides of the smart ring experience, as the fit fundamentally affects health tracking accuracy. This isn’t the case for smartwatches or fitness trackers, like the Apple Watch, where the straps can be easily adjusted. Bear this in mind if this is the first time you’re buying a smart ring.


Oura Ring size FAQs

As the sizing rings use plastic and the actual ring is a metal alloy, there will be slight sizing differences. However, these are largely negligible.

Yes, Oura’s return and exchanges policy entitles users to one exchange for a different size or color device in the same price range.

Yes, you’ll need an Oura Ring sizer before buying the actual device. The Oura Ring must be the correct size for your finger for comfort and fitness tracking accuracy. You can request a sizing kit from Oura or 3D print your own dummy rings using the company’s free 3D printing files.