Oura VO2 Max: How Cardio Capacity Works and How Accurate It Is
Run these workouts on your iPhone, or hands-free on Apple Watch. Get PEAKVO2 The Oura Ring estimates your VO2 max through a feature called Cardio Capacity, introduced in 2024. Because the ring has no GPS, it combines your heart rate from the ring with your phone's location during a guided six-minute walking test, and shows the result in the Heart Health section. It is a broad estimate, less accurate than a lab test, so trust the trend over the exact number, and remember Oura tracks your VO2 max but does not train it.
The Oura Ring is best known for sleep and recovery, but with Cardio Capacity it now gives you a VO2 max estimate too. Here is exactly how it produces that number, how far to trust it, how it stacks up against watches, and what actually moves it. For what your score means at your age, see our VO2 max charts by age and sex.
Does the Oura Ring Measure VO2 Max?
Oura estimates it rather than measuring it directly. In 2024 Oura added Cardio Capacity, its name for a VO2 max estimate, alongside a separate Cardiovascular Age metric (Oura, 2024). A true VO2 max measurement requires a mask and a metabolic cart in a lab. What Oura does instead is model your maximal oxygen uptake from data it can gather from a ring plus your phone. The result is an approximation, useful for tracking a trend, not a clinical figure.
Where to Find Cardio Capacity on Oura
Cardio Capacity lives in the Heart Health section of the Oura app, shown in the familiar ml/kg/min units alongside your Cardiovascular Age. The first value you see is a rough population estimate based on your profile; the walking test below refines it.
How Oura Calculates VO2 Max
Oura's approach reflects the ring's hardware. The ring reads heart rate and blood-flow signals but has no screen and, crucially, no GPS, so it leans on your phone for pace and distance (Oura Member Care). It works in two stages:
- Initial estimate from your profile. Before any test, Oura shows a number derived from anthropometric data: your age, sex, height, and weight. This is a population-average starting point, not a personal measurement.
- Refined estimate from a six-minute walking test. For a personal reading, Oura prompts a guided test: enable location services, then walk at a brisk pace on a straight, level, uninterrupted route with your phone and ring connected. Oura combines the distance from your phone's GPS with your heart rate from the ring to estimate your VO2 max. Oura suggests repeating the test roughly once a month to keep it current.
Because it is a submaximal walking test rather than an all-out effort, it infers your maximum from the heart-rate-to-pace relationship at an easy intensity, which is why it is an estimate rather than a direct reading.
How Accurate Is Oura's VO2 Max?
Treat it as a ballpark. Oura itself describes the walking-test result as a broad estimate of your cardiorespiratory health and is clear that it is not as accurate as a lab-based maximal test (Oura, Cardio Capacity). A few things affect the reading:
- It is walking-based. Submaximal tests extrapolate to your maximum, which adds error compared with a test that actually pushes you to exhaustion.
- The route matters. Stopping at crossings, hills, or an uneven pace during the test skews the distance-to-heart-rate relationship the estimate depends on.
- The absolute number can drift. As with every wearable estimate, the exact figure is less reliable than the direction it moves over time.
The practical takeaway is the same as for other wearables: the trend is the signal. If your Cardio Capacity climbs over months of training, that is real; do not agonize over a two-point difference between one test and the next.
Oura vs Apple Watch, Garmin, and Whoop
Each device estimates VO2 max differently, which is why their numbers rarely match exactly.
| Device | How it estimates VO2 max | Needs | Best for |
|---|---|---|---|
| Oura Ring | Six-minute walking test, ring heart rate plus phone GPS | A guided walk, roughly monthly | Ring wearers who want an occasional check |
| Apple Watch | Automatic from outdoor walks and runs (Cardio Fitness) | Outdoor GPS workouts | Passive tracking with no test |
| Garmin | Automatic from runs and rides via Firstbeat analytics | Outdoor runs or power-based rides | Runners and cyclists training by data |
| Whoop | Passive 24/7 model, refined by GPS runs | Continuous wear | Recovery-focused daily wearers |
If you want a deeper breakdown of the wearables, see our best fitness trackers for VO2 max comparison.
How to Raise the VO2 Max Oura Shows You
Here is the key point: Oura shows you the number, but it does not train it. Cardio Capacity is a tracker, and watching it stay flat is frustrating without a plan to move it. VO2 max rises with high-intensity interval training, and the trigger for the biggest gains is time spent near your maximum heart rate (Helgerud et al., 2007). The most reliable way to move the number:
- Do two to three interval sessions a week. The Norwegian 4x4, four intervals of 4 minutes at 90 to 95 percent of max heart rate, is the most studied protocol.
- Build an easy aerobic base on the other days so the hard sessions are productive.
- Retest monthly with Oura's walking test, and expect a measurable change after 6 to 8 weeks.
Oura tracks the trend; a training app runs the sessions that create it. PEAKVO2 guides the Norwegian 4x4, 30/30, and other VO2 max protocols on iPhone and Apple Watch with heart rate zones and automatic phases, then you watch your Oura Cardio Capacity climb. Follow the full 8-week VO2 max training plan to structure it.
Raise the number Oura shows you
PEAKVO2 runs the interval protocols that actually raise VO2 max, the Norwegian 4x4, Tabata, and 30/30, on iPhone and Apple Watch, with heart rate zones, spoken cues, and automatic phases. Three workouts free.
Get PEAKVO2 freeFrequently Asked Questions
Does the Oura Ring show VO2 max?
Yes, through a feature called Cardio Capacity, added in 2024. It shows a VO2 max estimate in ml/kg/min in the Heart Health section of the Oura app, starting from a profile-based estimate and refined by a six-minute walking test.
How does Oura measure VO2 max without GPS?
The ring itself has no GPS, so during the walking test Oura uses your phone's location for pace and distance and the ring for heart rate. It combines the two to estimate your VO2 max from how your heart rate responds to a known walking pace.
How accurate is Oura's Cardio Capacity?
It is a broad estimate, and Oura states it is less accurate than a lab-based maximal test. Because it is a submaximal walking test, the absolute number carries more uncertainty than the trend. Treat a rising trend over weeks and months as the meaningful signal.
How often should I do the Oura walking test?
Oura suggests about once a month. That is frequent enough to catch real fitness changes from training without the normal test-to-test noise making the number jump around.
Is Oura or Apple Watch better for VO2 max?
Neither is clearly more accurate; both are estimates. Apple Watch updates automatically from outdoor runs and walks with no separate test, while Oura requires a guided walking test but suits people who prefer a ring. For training, neither trains the number, so pair whichever you own with an interval program.
Can I improve the VO2 max Oura shows me?
Yes. VO2 max is highly trainable. Two to three high-intensity interval sessions a week, such as the Norwegian 4x4, typically raise it by 5 to 15 percent in 8 to 12 weeks. Retest with Oura monthly and the trend should climb.
Keep Reading
- Best Fitness Trackers for VO2 Max, Compared
- Whoop VO2 Max: How It Works and How Accurate It Is
- Garmin VO2 Max: How to Improve Your Estimate
- VO2 Max Training Plan: An 8-Week Program to Raise Your Number
- VO2 Max by Age: Chart of Normative Scores and What's Good
References
- Oura. Introducing Cardiovascular Age and Cardio Capacity. 2024. ouraring.com
- Oura. All About Cardio Capacity (VO2 Max). ouraring.com
- Helgerud J, Høydal K, Wang E, et al. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc. 2007;39(4):665-671. PubMed
- Mandsager K, Harb S, Cremer P, et al. Association of cardiorespiratory fitness with long-term mortality. JAMA Netw Open. 2018;1(6):e183605. PubMed