Oura Ring

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Related topics HRV (Heart Rate Variability), Activity tracking, Sleep tracking, Body temperature tracking, Heart rate tracking

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The Oura Ring is a wearable that is worn on a finger as a ring which tracks sleep, activity and readiness. Since 2013 there have been three different versions of the ring, with the latest version (v3) being launched in November 2021. At the same time they changed their business model, requiring a monthly subscription for access to all metrics recorded.

While the sensor set of the rings have changed over the versions, generally they contain an accelerometer, a temperature sensor as well as an optical heart rate sensor. From these sensors the Oura calculates the following metrics:

A generation 3 Oura Ring, showing some of the sensors on the inside of the ring

Differences between models[edit | edit source]

Model Sleep tracking Activity tracking Readiness tracking Heart rate

during sleep

Heart rate

during day




cycle tracking

Blood oxygen


Generation 1 [citation needed] [1]
Generation 2
Generation 3 [2] [3]

Metrics provided[edit | edit source]

Body temperature metrics[edit | edit source]

Oura does not report the absolute temperature recordings (neither through the phone app, nor through API data exports). Instead it provides two ways of reporting relative changes.

The daily view of body temperature displays how the average nightly body temperature compares to the average of all body temperature readings done in the past, thus comparing it to the baseline body temperature as recorded over time. As a result the average and median of all recordings will always be zero0.

The trend view of the body temperature is a bit more complicated. Oura states that "the trend view displays a weighted average of how your body temperature varies from your baseline based on a three-day window" and that "days closed to the current date will have more of an impact on your readings"[4]. Oura does not disclose the details of how the weighting of records is done and as such it is not possible to really understand or recreate how the company arrives at these values. One observation is that the trend values tend to be slightly biased towards positive values, probably as the distribution of possible body temperatures is not fully normally distributed, but rather censored on the lower end[5].

Use for menstrual cycle tracking[edit | edit source]

The rings of the 3rd generation include an Oura internal beta-test for cycle tracking. Furthermore, since mid-2022 the Natural Cycles app – a cycle tracking app that's cleared for use as birth control – can use the temperature data from the ring as main input to predict fertile time windows[6].

Exporting data[edit | edit source]

As for most wearables, there is unfortunately no (easy) way to access all raw data from the device. But Oura offers a way to download at least all of your calculated metrics from the Oura Cloud web interface. Beyond this, they also offer an API to automate access to Oura data in third party tools. An example implementation is the Oura integration into Open Humans, which automatically fetches the latest data at multiple times throughout the day and which since December 2022 gets data both from version 1.0 and 2.0 of the Oura API.

In January 2022, Oura announced a version 2.0 of their API for exporting data[7]. While it was under development this new API only provides access to more detailed activity data (such as intra-day heart rate), but as of December 2022 detailed information about readiness and sleep are also available[8]. For now the version 1.0 of the API still works and is scheduled to be sunset at some unspecified time in early 2023[9].

Subscription[edit | edit source]

When Oura released the 3rd generation of their ring, they announced that they would introduce a monthly subscription model that is priced at $5.99 before tax in the USA, €5.99 after tax in the EU and $6.99 after tax for the rest of the world. For users of a 3rd generation ring, the subscription is necessary to get full access to all the metrics the ring records. Early adopters were offered a 'free' lifetime subscription when upgrading to a 3rd generation ring at release at the end of 2021. Users of earlier generations are not required to switch to the subscription model. Oura has been criticized for introducing the subscription model at a time where the promised new features of the 3rd generation (see above) were not yet released. In June 2022 the blood oxygen tracking has still not been released.

Project using Oura Ring[edit | edit source]

Given the different kinds of sensors used in the Oura Ring, a diverse set of projects have been done with it:

References[edit | edit source]