Google Pixel & Fitbit VO2max: how it works.
The app compares your running pace with your heart rate during outdoor GPS runs, then compares that running efficiency with your resting heart rate. Since 2026 it no longer uses height and weight to calculate the score, and it can include runs from connected third-party apps.
What counts towards your VO2max
Estimated from: Outdoor run. Not used: Walk, Treadmill, Bike (power meter), Resting test, All-day data.
What you need to do
An outdoor run of at least 10 minutes with GPS. If no value appears, you may need up to three runs in 30 days.
How it is shown
VO2 max number placed in one of 6 levels from poor to excellent, based on age and sex.
Related features
- Fitness age: not confirmed
- Race predictor: not confirmed
- Cardio load and target load
- Readiness score
- Advanced running and form metrics (Pixel Watch 3, 4, 5)
- HRV
- Resting heart rate
Models
Google Pixel Watch 5 · Google Pixel Watch 4 · Google Pixel Watch 3 · Google Fitbit Air · Fitbit Charge 6
How accurate is it?
| Study | Finding |
|---|---|
| Lambe et al., PLoS One, 2026 | Pixel Watch 3 vs lab treadmill test (n=34): bias -0.53 mL/kg/min, limits of agreement -12.56 to 11.50, MAPE 8.65%. Funded by Google. |
| Klepin et al., Med Sci Sports Exerc, 2019 | Fitbit Charge 2 vs lab VO2max (n=60): bias +1.59 (15 s data) and +0.30 mL/kg/min (60 s data), MAPE under 10%. |
| Freeberg et al., mHealth, 2019 | Fitbit Charge 2 (n=30) overestimated: 52.5 vs 49.9 mL/kg/min measured, ICC 0.87, MAPE 10.2%. |
On May 19, 2026 the Fitbit app became the Google Health app, Cardio Fitness Score was renamed VO2 max, and Fitbit Premium became Google Health Premium. The new version needs GPS runs and drops the height/weight based estimate. The Fitbit studies tested the older Cardio Fitness Score. Google's data page lists many older Fitbit and Pixel Watch models as collecting VO2 max; Fitbit Air has no built-in GPS.
Frequently asked questions
How does Google Pixel & Fitbit calculate VO2max?
The app compares your running pace with your heart rate during outdoor GPS runs, then compares that running efficiency with your resting heart rate. Since 2026 it no longer uses height and weight to calculate the score, and it can include runs from connected third-party apps. An outdoor run of at least 10 minutes with GPS. If no value appears, you may need up to three runs in 30 days.
How accurate is Google Pixel & Fitbit VO2max?
3 published studies have tested it: Pixel Watch 3 vs lab treadmill test (n=34): bias -0.53 mL/kg/min, limits of agreement -12.56 to 11.50, MAPE 8.65%. Funded by Google.
Which Google Pixel & Fitbit devices show VO2max?
Examples: Google Pixel Watch 5, Google Pixel Watch 4, Google Pixel Watch 3, Google Fitbit Air, Fitbit Charge 6. Support depends on model and firmware.
Check your number against the norms for your age, estimate it with the VO2max calculator, or turn it into race times and paces.
Sources
- Google Health Help - What is new with the redesigned Google Health app
- Google Health Help - Learn about your VO2 max
- Google - What data Fitbit and Google Pixel Watch collect (device list)
- Google Health Help - Learn about cardio load and target load
- Google Health Help - Understanding your readiness score
- Google Health Help - Advanced running and form metrics for Pixel Watch 3, 4 and 5
Google Pixel & Fitbit is a trademark of its owner. VO2max Health is independent and not affiliated with Google Pixel & Fitbit. Features vary by model and firmware.