Fitness Age Calculator

Fitness age is the age at which your cardiorespiratory fitness, measured as VO2 max, equals the population average for your sex. If your fitness age is lower than your real age, your aerobic fitness is above average. If it is higher, you are below average for your years. The idea comes from research at the Norwegian University of Science and Technology (NTNU).

First it determines your VO2 max, either from the value you enter or from a non-exercise model that uses your sex, age, waist, resting heart rate and activity level. Then it finds the age whose average VO2 max matches yours, using sex-specific reference norms that decline with age. That matched age is your fitness age.

Switch the method to the proxy estimate. It uses the HUNT-study non-exercise equation from Nes and colleagues (2011), which predicts VO2 max from your waist circumference, resting heart rate, age and self-reported activity. This avoids any treadmill or running test, though a measured VO2 max is more accurate.

A larger waist is linked to more body fat and lower relative VO2 max, while a lower resting heart rate usually reflects a stronger, more efficient heart. The non-exercise model weights both, so trimming your waist or lowering your resting heart rate through training will lower your estimated fitness age.

Raise your VO2 max with regular aerobic training, especially higher-intensity intervals, plus steady endurance work. Most people can improve VO2 max by 10 to 20 percent over a few months of consistent training. Losing excess waist fat and improving resting heart rate also move the estimate in your favor.

No. This calculator is for education and general fitness tracking only and is not a substitute for professional medical advice, diagnosis or a supervised exercise test. Talk to a doctor before starting a new training program, especially if you have a heart condition, are over 45, or have other health concerns.