Galaxy Watch vs Pixel Watch & Fitbit: VO2max compared
How Galaxy Watch and Pixel Watch & Fitbit estimate your VO2max, what each needs from you, what else they show and what independent studies say about accuracy.
| Galaxy Watch | Pixel Watch & Fitbit | |
|---|---|---|
| Called | VO2 max | VO2 max (called Cardio Fitness Score before 2026) |
| Algorithm | Not disclosed | Not disclosed |
| App | Samsung Health | Google Health app (called the Fitbit app until May 19, 2026) |
| From: Outdoor run | Yes | Yes |
| From: Walk | Not confirmed | No |
| From: Treadmill | Not confirmed | No |
| From: Bike (power meter) | Not confirmed | No |
| From: Resting test | Not confirmed | No |
| From: All-day data | Not confirmed | No |
| Fitness age | Not confirmed | Not confirmed |
| Race predictor | Not confirmed | Not confirmed |
| Published accuracy studies | 0 | 3 |
| What you need to do | Start a running workout on the watch (auto-detected workouts may not count). Run at least 4 km/h for 10 minutes on a flat path with good GPS signal and continuous heart rate on. | An outdoor run of at least 10 minutes with GPS. If no value appears, you may need up to three runs in 30 days. |
Key differences
- Accuracy evidence: we found 0 published studies for Galaxy Watch and 3 for Pixel Watch & Fitbit.
How each one works
Galaxy Watch: The watch measures VO2 max during a running workout using heart rate and GPS data. Samsung does not publish how the estimate is calculated.
Pixel Watch & Fitbit: 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.
Which is better for VO2max?
For VO2max specifically, the best device is the one that sees your hardest efforts: if most of your training is outdoor running, both give an estimate (both use outdoor run). If you cycle with a power meter, walk more than you run, or want a resting test, check those rows above. Whichever you choose, compare the number with itself over time and with the norms for your age.
Accuracy studies
Galaxy Watch
No published, peer-reviewed validation found.
Pixel Watch & Fitbit
- 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%.
Frequently asked questions
Is Galaxy Watch or Pixel Watch & Fitbit more accurate for VO2max?
Pixel Watch & Fitbit has more published validation (3 vs 0 studies). Watch estimates are typically within several ml/kg/min of lab tests for groups, with larger individual errors, so use either one to track your trend.
Does Galaxy Watch measure VO2max from outdoor run like Pixel Watch & Fitbit?
Yes: both estimate from outdoor run.
Which is better for VO2max: Galaxy Watch or Pixel Watch & Fitbit?
Pick the one whose data sources match how you train: Galaxy Watch uses outdoor run; Pixel Watch & Fitbit uses outdoor run.
Built from official documentation (see each brand page for sources). Features vary by model and firmware. Galaxy Watch and Pixel Watch & Fitbit are trademarks of their owners; VO2max Health is independent and not affiliated with either.