Estimate your aerobic fitness level using a quick heart rate ratio, or the more involved Rockport 1-mile walk test.
VO2 max is the maximum amount of oxygen your body can use during intense exercise, measured in millilitres of oxygen per kilogram of body weight per minute. It's one of the most reliable single indicators of cardiovascular fitness and aerobic endurance capacity.
This non-exercise method, developed by Uth, Sørensen, Overgaard, and Pedersen, estimates VO2 max from the ratio of your max heart rate to your resting heart rate. It's fast and requires no exercise test, but is less precise than a field or lab test.
Walk one flat mile as briskly as you safely can, record your finish time and heart rate immediately at the end, and the calculator estimates VO2 max from your walk time, ending heart rate, age, sex, and weight. It was developed for general adult populations rather than trained athletes.
Both methods are estimates, not direct measurements. A laboratory graded exercise test with gas analysis remains the gold standard; field tests like these are typically within about 10–15% of a true lab value for most people.
The heart rate ratio method is faster and fine for tracking general trends over time. The walk test takes more effort but tends to be more accurate since it's based on an actual physical performance rather than resting numbers alone.
Consistent aerobic training is the main driver — a mix of steady-state cardio and higher-intensity interval sessions over several months reliably raises VO2 max in most people, including those starting from a low baseline.