The Apple Watch V02 Max Accuracy

First of all, what is VO2 max and how do you measure your personal VO2 max? Here’s a quick FAQ on VO2 Max.

The only accurate way to measure VO2 max is to wear a face mask and actually measure the amount of oxygen flowing through the mask and to your lungs. Obviously, the Apple Watch doesn’t come with a face mask attachment you can connect via Bluetooth, yet. So how does Apple Watch measure V02 Max?

Apple watch uses a metric known as “Predicted V02 Max” and is based on your heart rate activity during exercise. Since the relationship of the heart rate and the VO2 max varies between everyone, it’s not a perfect indicator of your VO2 max, but with regular testing, you can see the trends of improvement or decline in relation to your own VO2 max baseline.

There have also been reported issues with Apple Watch’s heart rate sensor and its lack of accuracy, especially when comparing heart rate sensors you strap on directly to your chest. We’ve been experimenting with the chest strap ourselves so we’ll update you on the findings and comparisons between chest straps and the Apple Watch soon.

Products To Look Into For Tracking VO2 Max


Although the VO2 max measured on the Apple Watch is an interesting metric, the lack of accuracy in comparison to your real VO2 max makes it a less useful stat to track. Hopefully, as technology and sensors improve, the VO2 max measurement on the Apple Watch will come closer to your actual VO2 max.

Nevertheless, for those who love numbers and like to track as many stats as they can, this is an article on how to measure your VO2 max using the Apple Watch.

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2 thoughts on “The Apple Watch V02 Max Accuracy”

  1. After considerable experimentation with Apple’s VO2max metric, my view is that a user could be significantly misled by the crude metric it displays.

    One example: my temporary location for the past few months provided the opportunity to climb a steep trail which, at my speed, was roughly 20 minutes up. A mid-point plateau provides an opportunity to climb the hill 1x, 1.5, 2x and so forth. In climbing this hill several times a week over a period of months, I watched my objective and subjective fitness metrics improve, including heart rate recovery, climb speed, perceived oxygen deficit and breathing rate, and heart rate for a given rate of climb. In short, the hill — difficult at first — became easy and I had to push harder and harder to get a good workout.

    At the same time, according to Apple, my fitness as indicated by VO2max was declining, not by a great deal steadily creeping downward. Apple’s metric appears to recognize only running or walking at a steady pace on smooth and level ground. Even then, it does not appear to be programmed correctly for the reduced heart rate that occurs for a given exercise as fitness increases.

    A more significant shortcoming of the Apple 6 watch is that it will occasionally stop registering heart rate when the exercise tracker is active. The problem seems to occur most often at high rates. Rebooting fixes the problem but spoils the exercise if you are tracking your performance.

    • These are great observations. I just upgraded from a Series 3 to Series 7 watch and all of a sudden my VO2max went from 40.7 to 43.2. Since switching its been holding this average. Haven’t changed up my exercise routine or added anything new except for the upgraded watch. Series is older so maybe the additional newer sensors might have contributed to the change, but even so still gives some pause to the accuracy of this measurement. That being said, most experts say that the only true way to test VO2max is to do the incline treadmill test where you have the mask strapped to your face.

      As for heart rate tracking, if I’m looking to get the most accurate and up-to-date readings I’ll use my chest strap paired to the watch. Not only does it read better for doing workouts with weights, but it also is much more responsive to tracking heart rate. Basically, very short lag when heart rate increases or decreases. As an added bonus, you can also use the chest strap for more accurate HRV readings.


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