Apple Health already estimates your VO2 max. This app makes it readable: the trend, a target range, a year of history, and a fitness-age estimate.
iPhone · Apple Watch · Widgets
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Free to start. VO2+ adds the deeper context.
The most recent Apple Health cardio fitness reading, with its date, in large clear type.
One plain-language verdict on where your aerobic fitness is heading, not just a number.
Every estimate Apple Health has stored, charted so seasonal dips and training blocks are obvious.
Your current VO2 max and trend without opening the app.
Check the number on your wrist, with complications for your watch face.
A personal target range for your age and sex, so the number has a reference point.
A fitness-age estimate derived from your cardio fitness, with the methodology explained in the app.
Clear instructions on the outdoor walks and runs Apple Watch needs to produce an estimate.
The app reads cardio fitness and never writes anything back to Apple Health.
The app reads cardio fitness estimates from Apple Health only after you grant permission, and never writes Health data. Health and profile values are processed and stored on your devices. Nothing is sold, used for advertising, or uploaded to a server. Apple and RevenueCat process purchases only; no Health data is sent to them.
Privacy Policy →How it's built and why it matters.
Apple Watch quietly estimates your VO2 max on outdoor walks, runs, and hikes, and then buries it in the Health app behind a chart most people never open.
This app pulls that estimate to the front: the current value, whether it's improving, a target range for your age, a year of history, and a fitness-age read. No logging, no workouts to start, no account. Open it and the number is there.
The dashboard, trend, widgets, and Apple Watch app are free. VO2+ is $1.99/month, $14.99/year (both with a 7-day free trial for eligible new subscribers), or $29.99 once.
Target range. A personal range for your age and sex, so you can see how much headroom you have.
Fitness age. A broad estimate from your cardio fitness, with the methodology written out rather than hidden.
Full history. The complete set of estimates Apple Health holds, not just the recent window.
| Platform | iOS 17+, watchOS 10+ |
| Language | Swift 6 with strict concurrency |
| Framework | SwiftUI · HealthKit · WidgetKit · SwiftData |
| Data | Read-only HealthKit access, local only |
| Storage | Local cache shared with widgets via App Group |
| Widgets | Home Screen, Lock Screen, watchOS complications |
Nothing to log. The app has no input fields for fitness data. Everything it shows comes from HealthKit, which means it's correct or it's empty, never guessed.
Honest about estimates. VO2 max from a wrist is an approximation, and fitness age is an approximation of an approximation. The app says so and shows its method.
Empty state as a feature. Plenty of users have no estimate yet. Instead of a blank chart, the app explains exactly which workouts generate one.
Read-only by design. Requesting write access to Health would have been easier for caching. It wasn't worth the trust cost.
VO2 max and fitness age are broad estimates for fitness awareness. This app does not diagnose, treat, cure, or prevent any health condition, and it is not a substitute for professional medical advice.
Free on the App Store. No account required. VO2+ optional.
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