Updated October 2026. VO2 max is one of the best single numbers for cardiovascular fitness, and you no longer need a lab treadmill and a mask to get an estimate. Most good running watches and many fitness trackers now estimate it from your heart rate and pace. Some do it much better than others.
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Table of Contents
What Is VO2 Max?
VO2 max is the maximum amount of oxygen your body can use during hard exercise, measured in milliliters per kilogram of body weight per minute (ml/kg/min). A higher number means a stronger heart and lungs. It is also linked to long-term health: research ties higher cardiorespiratory fitness to lower risk of heart disease and early death.
How Do Watches Estimate VO2 Max?
Watches compare your heart rate with your speed during outdoor runs or walks with GPS, or with power on a bike with a power meter. If your heart rate stays lower at a given pace, your estimate goes up. Garmin uses analytics from Firstbeat, Apple uses its Cardio Fitness model, and Fitbit gives a Cardio Fitness Score range.
The estimates are useful for tracking trends, not as a medical test. Validation studies generally find good watches land within a few points of lab tests for most people, with bigger errors for very fit or very unfit users. To get better estimates: run outdoors with GPS, enter your correct age, weight and max heart rate, and pair a chest strap.
Quick Comparison
| Device | Type | VO2 max for | Best for |
|---|---|---|---|
| Garmin Forerunner 265 | Running watch | Running and cycling (with power) | Best overall |
| Garmin Forerunner 165 | Running watch | Running | Best value |
| Garmin Forerunner 965 | Running watch | Running and cycling | Serious training |
| Garmin fenix 8 Solar | Adventure watch | Running and cycling | Outdoor and multisport |
| Garmin Venu 3 | Smartwatch | Running and walking | Health-focused users |
| Apple Watch Series 10 | Smartwatch | Outdoor walks, runs and hikes | iPhone users |
| Samsung Galaxy Watch 8 | Smartwatch | Running | Android users |
| Fitbit Charge 6 | Fitness band | Cardio Fitness Score | Budget band |
The Best Watches and Trackers With VO2 Max
1. Garmin Forerunner 265
The Forerunner 265 gives you Garmin’s full set of training metrics in a light watch with an AMOLED screen: VO2 max, training status, training readiness, recovery time and race predictions based on your fitness. It is accurate, easy to read and has days of battery even with daily runs.
What we like
- Excellent VO2 max and training status tracking
- Bright AMOLED display
- Light and comfortable
Keep in mind
- No maps, unlike the 965
2. Garmin Forerunner 165
The 165 brings Garmin’s VO2 max estimate and training tools to a lower price. You lose some advanced features like training readiness and multiband GPS, but the core fitness metrics are the same. It is the best way to start tracking VO2 max on a budget.
3. Garmin Forerunner 965
The 965 adds full-color maps, multiband GPS and more battery to everything in the 265. It also estimates VO2 max for cycling when paired with a power meter. Pick it if you train a lot, race, or go off-route.
4. Garmin fenix 8 Solar
The fenix 8 is Garmin’s premium outdoor watch with sapphire glass, a titanium bezel, solar charging and maps. It has all of Garmin’s fitness metrics, including VO2 max with heat and altitude acclimation. It is expensive and large, but it lasts weeks between charges.
5. Garmin Venu 3
If you want VO2 max without a sporty look, the Venu 3 is Garmin’s lifestyle smartwatch. It tracks VO2 max from runs and walks and adds sleep coaching, Body Battery and an ECG app in the US.
6. Apple Watch Series 10
Apple Watch estimates VO2 max as “Cardio Fitness” during outdoor walks, runs and hikes, and can notify you if your level drops low for your age. The Health app shows how you compare with others your age and sex. Newer Apple Watch models are also available; all recent ones support Cardio Fitness.
7. Samsung Galaxy Watch 8
Galaxy Watch estimates VO2 max during runs and shows it in Samsung Health, alongside running coaching, sleep tracking and an antioxidant index. It is the best all-round smartwatch for Samsung phone owners.
8. Fitbit Charge 6
Fitbit shows a Cardio Fitness Score, which is a VO2 max estimate shown as a range. It is less detailed than Garmin’s number, but it tracks trends well, and the Charge 6 is small, affordable and has built-in GPS.
Improve Accuracy With a Chest Strap
Optical sensors struggle during hard efforts and in cold weather. A chest strap like the Polar H10 gives your watch clean heart rate data, which leads to more reliable VO2 max estimates. It pairs with Garmin, Apple, Samsung and Polar devices.
Frequently Asked Questions
What is a good VO2 max for my age?
It depends on age and sex. As a rough guide, values in the mid-40s are good for men in their 30s and the high-30s are good for women in their 30s, with expected values falling with age. Your watch app shows where you stand compared with your age group.
How can I improve my VO2 max?
Consistent cardio training works. Combine mostly easy aerobic sessions with one or two harder interval sessions a week. Losing excess weight also raises VO2 max because it is measured per kilogram.
Is SpO2 the same as VO2 max?
No. SpO2 is the percentage of oxygen in your blood at a moment. VO2 max is how much oxygen your body can use during maximum effort.
Does Fitbit show VO2 max?
Yes, as the Cardio Fitness Score in the Fitbit app.
Bottom Line
For accurate VO2 max tracking, Garmin’s Forerunner 265 is the best choice for most people, and the 165 is the value pick. iPhone users get solid Cardio Fitness tracking with Apple Watch, and Android users with the Galaxy Watch 8. Add a chest strap if you want the most reliable numbers.
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As a professional trainer and a gadget lover, I’ve spent a lot of money and time buying wearable activity trackers, smartwatches, and gadgets, and checking them out. My site is focused on helping you with your activity tracking and smart technology journey. I try to provide the most helpful updated content on this subject. Hopefully, you will love my blogs and be a regular around here.
