Oura ring size vs your regular ring size
An Oura ring size is often not the same number as the rings you already wear, because Oura numbers its sizes in its own way. Oura suggests wearing a sample ring from its sizing kit for a whole day and night before you choose. Here is how the kit works, and how Oura's sizes compare with other smart rings (rings that track your sleep and health) from Samsung, Ultrahuman and RingConn.
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Is an Oura size the same as a normal ring size?
Not always. Oura numbers its sizes its own way, so if an ordinary size 7 fits you, your Oura may be a different number, as Oura's own help page explains.
Oura only makes whole sizes, with no halves. If you usually wear a half size, the kit lets you try the sizes just above and just below, so you can feel which one is right.
Oura ring sizing kit
Oura sells a sizing kit so you can try its sizes at home. You wear a plain sample ring to see how it feels, then order the real ring in the size that fitted best.
Oura's sizing guide explains how to get the kit and what you pay for it. The other brands send out their own kits, and your size with one brand won't tell you your size with another.
Oura ring size chart
The two Oura models come in different ranges of sizes. Every size is a whole number.
| Model | Smallest | Largest | Half sizes |
|---|---|---|---|
| Oura Ring 4 | Size 4 | Size 15 | No |
| Oura Ring 5 | Size 6 | Size 13 | No |
Oura doesn't list its sizes in millimetres, so trying the kit is the reliable way to find yours.
How to find your Oura fit
Oura wants you to check the fit through a whole day, so you know the ring stays comfortable in the morning, in the evening and in bed.
- Choose the Oura model you want, then order the kit from Oura's sizing page.
- Put one sample ring on the finger you plan to wear your Oura on, so the test is like everyday wear.
- Keep it on for a full day, and sleep in it.
- If it feels too tight or too loose, try the next sample ring and do the same.
- Order the size that stayed comfortable all day and all night.
How does Oura sizing compare with other brands?
Every brand sends out a sizing kit. What changes is the range of sizes and the advice.
| Brand | Sizes | What the brand suggests |
|---|---|---|
| Oura Ring 4 | 4 to 15 | Wear the sample ring day and night |
| Oura Ring 5 | 6 to 13 | Wear the sample ring day and night |
| Samsung Galaxy Ring | 5 to 15 | Your usual size may feel different, because of the parts inside |
| Ultrahuman | Kit has 5 to 14 | Wear the chosen size for at least two nights |
| RingConn Gen 2 | Kit has 6 to 14 | If you are between two sizes, RingConn suggests the smaller one |
The Ultrahuman kit comes with plastic sample rings, and the RingConn kit is free.
Samsung's Galaxy Ring kit and sizes
Samsung's Galaxy Ring comes in sizes 5 to 15, and, like Oura, Samsung offers a sizing kit. Samsung warns that your usual size might not fit, because the sensors (the small parts inside the ring that take its readings) change how it feels.
Of the brands here, only Samsung lists how wide its rings are inside, in millimetres.
| Samsung size | Across the inside (mm) |
|---|---|
| 5 | 15.7 |
| 7 | 17.3 |
| 13 | 22.2 |
These figures come from Samsung's size guide. So a Samsung size 7 is about as wide as an ordinary size 7 ring. Even so, Samsung says the sensors can change how it feels, so the kit is still worth trying.
Questions people ask
Size 7 or 8: which Oura should I choose?
Oura doesn't make a 7½, so the choice is between the 7 and the 8. Wear each sample ring from the kit for a full day and night, and you will know which one fits best.
Is there a way to convert an Oura size to jewellery sizing?
Not directly. Your usual ring size is a good place to start when you choose which sample rings to try, and the kit does the rest.
Do Oura sizes use mm or cm?
Neither. Oura only gives size numbers, so the sizing kit is how you find yours. For an ordinary ring, the ring sizer on this site's home page turns a paper strip measurement in millimetres into a size.