VO2 Max Calculator
Estimate your VO2 max — a standard measure of cardiorespiratory fitness — using your resting heart rate.
About this non-exercise estimate
VO2 max — the maximum amount of oxygen your body can use during intense exercise — is typically measured precisely in a lab using specialized equipment during a graded exercise test. This calculator instead uses a non-exercise regression formula based on the relationship between resting heart rate and estimated maximum heart rate, which is far more accessible but also less precise than direct testing.
This estimate tends to be reasonably useful for tracking your own trends over time (is your resting heart rate improving as you get fitter?) even if the absolute number isn't as precise as a lab test would provide.
Why resting heart rate reflects fitness
A lower resting heart rate generally indicates a more efficient cardiovascular system — a well-conditioned heart can pump more blood per beat, requiring fewer beats per minute to meet the body's resting oxygen demand. This is why endurance athletes often have notably low resting heart rates compared to sedentary individuals of the same age.
Resting heart rate is best measured first thing in the morning before getting out of bed, when your body is in its most relaxed, undisturbed state — measurements taken later in the day after activity, caffeine, or stress tend to run higher and less representative.
Frequently asked questions
How accurate is this compared to a lab VO2 max test?
This non-exercise formula is a reasonable estimate but is less precise than a supervised lab test with breathing gas analysis — it's most useful for tracking general trends over time rather than as a precise clinical measurement.
When should I measure my resting heart rate?
First thing in the morning before getting out of bed generally gives the most accurate and consistent reading, since your body is in its most relaxed state at that point.