




📏 Nail your perfect fit before you buy — because precision is the new luxury.
The Oura Ring 4 Sizing Kit is an essential tool designed to help you find the exact fit for your Oura Ring 4, which uses unique sizing different from standard US rings. By ensuring a secure and comfortable fit on your chosen finger, it optimizes sensor accuracy and overall user experience. The kit is reusable, works on all fingers and hands, and includes a $10 credit redeemable against your Oura Ring 4 purchase, making it a smart, risk-free step towards better health tracking.












| ASIN | B0D9WVWXR1 |
| Best Sellers Rank | #330 in Clothing, Shoes & Jewelry ( See Top 100 in Clothing, Shoes & Jewelry ) #2 in Ring Sizers |
| Color | Sizing Kit |
| Customer Reviews | 4.6 4.6 out of 5 stars (2,526) |
| Date First Available | October 3, 2024 |
| Item Weight | 1.76 ounces |
| Item model number | JZ98-54870 |
| Manufacturer | Oura |
| Other display features | Wireless |
| Package Dimensions | 6.57 x 4.45 x 0.47 inches |
| Special features | Heart Rate Monitor, Activity Tracker, Sleep Monitor |
| Whats in the box | Oura Ring 4 Sizing Kit |
A**I
Love this ring!
Within the 6 months of having this ring I’ve noticed that scratches have only really appeared where I hit my finger against my computer mouse at work. The rest of the ring looks great! I have some sleep and health issues so this tracking has immensely helped me find out what I need to adjust. Based on your sleep score, temperature, and heart rate, the app will let you know if something is going on - especially illnesses. It’ll let you know something minor is straining your body when you are going to be sick the following day, then show major signs when you’re actually sick, which gives great peace of mind. I also started a new medication and my general scores lately, along with other factors, have shown that I need to revisit this medication choice. I’ve also really enjoyed the cycle tracking while being off of birth control, this along with ovulation testing has been the best hormone free birth control. This has been the most accurate tracking and prediction I’ve had, in comparison to Flo and Stardust. These rings are amazing if you’re looking to have some motivation for activity, cycle tracking, sleep monitoring, and general peace of mind.
A**R
1) Ōura Ring Sizing Kit / 2) Ōura Ring 4 Reviews / 3) Addendum Item
Amazon, despite complaints, views the Ōura Ring Sizing Kit as the same or a similar item as the Ōura Ring 4, itself... thus, two DIFFERENT reviews AND ratings for two COMPLETELY DIFFERENT products. -------------- 1) THE ŌURA RING SIZING KIT / 5-Stars Ōura states that the Ring 4 sizes are NOT the same as traditional ring sizes. I did NOT break out my Ring Sizing Loops to determine the veracity of that statement because the cost, of the Ring 4 Sizer, on Amazon is applied as a credit towards the cost of an Ōura Ring 4 WHEN purchased via Amazon. I will say that there is perhaps a little difference, compared to traditional ring sizes, but I'm not sure that it's much because I ended up with the ring size that I thought would work. Interestingly enough, size 10 that I expected for the middle finger was a perfect fit for the Index finger, which is normally a traditional 9... so there is some difference in the sizing and I wholeheartedly recommend procuring the Ōura Ring 4 Sizer BEFORE purchasing the Ōura Ring 4. NOTE that the Ōura Ring 4 Sizer does not work for all Ōura Ring models, so anyone deciding to purchase a previous iteration of the Ōura Ring, due to cost decrease and/or a Sale, will need to utilize the correct Ōura Ring Sizer for the model ring chosen. If there is a question of Sale or Discount Pricing, due to the delay from checking ring sizes, then I suggest an online Chat with Amazon Customer Service representative to make sure that you can lock in any discounts to use after verifying the correct Ring size. FYI - Ōura recommends wearing the sizing ring on the finger that will bear the ring, in order to become accustomed to the ring size/feel and to see how well it fits throughout a normal day. I followed that advice and I believe that everyone should do the same. ---------------- 2) Ōura Ring 4 / 1-Star First, even with the ring sizing kit and wearing the sizer non-stop until the Ring 4 arrived, the size of the Ring 4 in only whole sizes proved inadequate. My hands clearly fluctuate enough in size to be an issue, regardless of the finger or hand that is used. Next, the heart rate (HR) was always available and showing in the app, signifying that the Ring 4 was measuring the HR, HOWEVER, the app called to show the graph of the HR for over two (2) weeks, meaning there was no history nor any assessment available. Next, the Sleep function, even with learning curve, seemed to function out of the box, HOWEVER, after the first recharge of the Ring 4, there was an issue with accurately recording start and stop points of Sleep AND eventually the app would show No Sleep Data AFTER uploading/updating UNTIL THE NEXT day. There was no event showing for sleep ALTHOUGH the Ring 4 clearly annotated the Start of the Sleep period the previous night. Next, even after more than three (3) weeks of use, the app has failed to graph the Blood Oxygen Saturation, in spite of showing the data observed and available to see at any given moment. Again, I find this to be very odd and indisputably useless to the user. Next, the App is full of "flash" or substance but in terms of a quick overall view of all the numbers, like most Apps, no such uncluttered view can be found. While the plethora of information and links is appreciated, the search to locate immediate data numbers across all items is tedious, frustrating and unappreciated. To provide an analogy, it's like having to read an entire book to search for and locate the Synopsis of the book. For those who aren't into books, then it's like watching a TV and THEN SEEING the Preview for the show that you just watched. I and most users seem to prefer a Table of Contents approach where the Raw Data is shown and then you can click to go to the Analysis, Assessment and Suggestions for that particular Biometric. In short, the App's interface is beautifully flashy and showy but about as useful up front as a Show Pony on a crop farm. That makes it overwhelming, even to those who are focused readers and moreso to the vast majority who are not. Finally, many details and assessments are NOT available for anywhere from four (4) weeks to three (3) or more months. While understandable, it makes it impossible to fully assess the personal value and utility of the Ring 4 in the 30-day period for returns. That means that the $400+ ring and the annual subscription fee is only acceptable for those with money to burn, so to speak, because all of the shortcomings or issues, even if expandable and temporary, outweigh the cost of what is actually a pretty doggone accurate piece of tech wear, resulting in the clear choice to return the ring. AND... there is one other issue to consider which is that if your hands swell, perhaps from work, or shrink, perhaps from weight loss, then your $400+ ring AND subscription become useless... until you purchase another Ōura Ring that does fit. Based on my research and experience, there are equally accurate smart fitness watches with solid Apps and reasonable insights and suggestions based on the assessment of the biometrics. Also, there is another smart ring on the market that appears to rival the Ōura Ring in accuracy, provides an seemingly identical App for all appearances seen, comes as an adjustable ring using the same high-end materials and sensor setup AND which additionally boasts being approved and classified as a Medical Grade Device, instead of a Consumer Grade Device. All of that at a far, far lower cost AND the same updates, assessments, insights and suggestions BUT with NO subscription fee. That being said, I am a Go/No-Go tester of products meaning things are either 5-star or 1-star with enough details for people to decide that my 1-star item might be good enough to be their 3- or 4-star item. The Ring 4 failed to make the grade for my needs nor was it able to justify keeping the ring to see if things improved or the money was worth the extended wait for certain observations, but it was remarkably accurate when comparing data to manual results, such as HR, SpO2, etc. There is no blood pressure data, for those in search of BP function. I am not sure that BP could be accurately obtained below the wrist at this point in technology, but maybe in the future. REMEMBER that when returning an Ōura Ring, you MUST also CANCEL the Ōura App Subscription as it is a separate financial issue from the purchase. The subscription is free for the first 30-days and a part of setting up your account before you are able to use the App, so it's an easy thing to forget. 3) Addendum -- there is a charging cable organizer with a carabineer that works GREAT for the Ōura Ring 4 charging station and cable that is available on Amazon AND IS HIGHLY RECOMMENDED. That is my next review and it will be 5-Stars. It was kind of a why-the-heck-not afterthought purchase that became an INSTANT 5-Star Should Have item as soon as I unpackaged it!!!!
N**E
Absolutely Essential Before Buying Your Oura Ring
This sizing kit is hands down the best thing to purchase before ordering an Oura Ring. The sizing runs differently than regular jewelry, so trying the sample rings first made a huge difference in choosing the perfect fit. I loved being able to wear a size for a full day to see how it felt during normal activities, sleeping, and slight finger swelling. It gave me confidence that I was ordering the correct size and avoided the hassle of returns or exchanges. If you’re even slightly unsure about sizing, get this first. It’s a small step that saves time, stress, and money in the long run. Highly recommend! ⭐⭐⭐⭐⭐
J**O
Christmas Gift
This was a Christmas gift if you don’t know what size you’re really gonna need I would say purchase the ring sizer kit, which only cost $10 and when you send it back, they put they put that on the purchase of your OURA RING. My wife absolutely loves hers. She wanted one a year before, but they didn’t have her size and I got the wrong size and I had to send it back which was not a problem, but I purchased one for her for this Christmas and she was it every day.
S**H
Perfect fit
This was absolutely perfect to help me determine my ring size before buying the oura ring. The fit of the tester band was the exact same size as the oura ring. I loved that I was able to wear it for a day and try it out before buying the actual ring. I found this kit very helpful in finding the most comfortable size
D**A
Sizing kit but no credit!
Exactly what I needed! Got the sizing kit on here instead of the website! I was definitely in between sizes and feel more comfortable getting this kit! Also tried my friend’s oura ring and it was pretty accurate! This kit does NOT give a credit like it states! Can’t wait to order!
T**R
Make sure yiu get these before buying the ring!
I thought I wore a size 12 ring until I tried these. Turns out I needed a size 15. One thing to know about these rings is that they require a monthly subscription which adds to the cost and means your health information will be collected and not private. I chose against buying the ring because I want my data to remain mine!
D**A
It does exactly what it says it does
It does exactly what it says it does. The rings are comfortable to wear and made it easy to figure out the right size before ordering the actual Oura Ring. I also appreciated being able to wear it for a full day to see how it felt during normal activities and while sleeping. Simple, accurate, and definitely worth using to avoid sizing issues
A**ー
後で判明したがアマゾンとその他で1000円近く値段が違う。類似の商品にも出て来なかった。 24時間装着とあったので着けて寝たら、かぶれでしまった。本商品とは素材が違うが、高いので怖くて買えない
F**G
Great sizing tool. However, Amazon SG doesnt allow the actual Oura Ring to be delivered. The status has been “Ordered Received…”
Z**Z
Great works as advertised
D**A
Satisfecha con el producto
N**K
Perfect service
Trustpilot
3 weeks ago
1 month ago