VO2 Max Estimator (Resting Heart Rate)
Estimates your VO2 max — the maximum amount of oxygen your body can use during intense exercise — from your resting heart rate and age, with no treadmill test required. It uses the Uth–Sørensen heart-rate-ratio method, a quick proxy for cardiorespiratory fitness.
Last updated: May 2026
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About this calculator
VO2 max is the gold-standard measure of aerobic fitness: the maximum volume of oxygen (in millilitres) your body can consume per kilogram of body weight per minute at peak effort. A true VO2 max test requires a metabolic cart and a maximal treadmill or cycle ergometer protocol, which is expensive and exhausting. The Uth–Sørensen estimate sidesteps that by exploiting a simple physiological relationship: fitter hearts pump more blood per beat, so they beat more slowly at rest. The formula is VO2 max ≈ 15.3 × (HRmax ÷ HRrest), where HRmax is approximated as 220 − age. For a 30-year-old with a resting heart rate of 60 bpm, HRmax is 190, the ratio is 3.167, and the estimate is about 48.5 ml/kg/min — solidly in the "good" range for that age. Because the method leans entirely on resting heart rate, accuracy depends on measuring HRrest correctly: take it first thing in the morning, lying down, before caffeine or movement. The 220 − age maximum-heart-rate rule is itself a population average with a standard deviation of roughly 10–12 bpm, so individual estimates can be off by several points. Treat the number as a ballpark and a way to track your own trend over months, not as a clinical measurement. Typical reference values: 35–40 (fair), 40–50 (good), 50+ (excellent) for adult men, with women generally running a few points lower.
How to use
Example 1 — Recreational runner. A 30-year-old measures a resting heart rate of 60 bpm. Enter 60 and 30. Result: 48.45 ml/kg/min. Verify: 220 − 30 = 190; 190 ÷ 60 = 3.1667; 3.1667 × 15.3 ≈ 48.45. ✓ That places them in the "good-to-excellent" band for their age. Example 2 — Sedentary office worker. A 45-year-old with a resting heart rate of 80 bpm enters 80 and 45. Result: 33.49 ml/kg/min. Verify: 220 − 45 = 175; 175 ÷ 80 = 2.1875; × 15.3 ≈ 33.47 (small rounding). ✓ This is in the "fair" range and would be expected to rise as resting heart rate falls with training.
Frequently asked questions
How accurate is estimating VO2 max from resting heart rate?
It is a rough estimate, not a laboratory measurement. The Uth–Sørensen method was validated against treadmill testing in trained men and showed good correlation, but the error for any single individual can be several ml/kg/min. Two things drive the inaccuracy: the 220 − age formula for maximum heart rate is a population average with wide individual variation, and resting heart rate is sensitive to sleep, stress, caffeine, and hydration on the day you measure it. Use this tool to track your own trend over weeks and months rather than to compare yourself precisely against published norms or other people.
How do I measure my resting heart rate correctly?
Measure it first thing in the morning, before you get out of bed and before any caffeine. Lie still for a minute, then count your pulse at the wrist or neck for 60 seconds, or use a chest strap or fitness watch that records overnight. Avoid measuring after meals, exercise, or stress, all of which raise heart rate temporarily. For the most reliable figure, average three or four mornings. A single elevated reading after a poor night of sleep will make your VO2 max estimate look worse than your real fitness.
What is a good VO2 max for my age?
VO2 max declines gradually with age and is generally lower in women than men of the same fitness. For men in their 30s, roughly 35–40 ml/kg/min is fair, 40–50 is good, and above 50 is excellent; elite endurance athletes exceed 70. Women typically run about 5–10 points lower at each fitness level. These bands are broad because genetics set a large part of your ceiling, but consistent aerobic training can raise VO2 max by 15–20% over months. The most useful comparison is your own past values, not a chart.
What mistakes do people make with this estimate?
The most common mistake is using a resting heart rate taken at the wrong time — after coffee, after climbing stairs, or during a stressful afternoon — which inflates the number and understates fitness. Another is treating the single output as a precise, clinical VO2 max and making training decisions on small changes that are really just day-to-day noise. People also forget that beta-blockers and other heart-rate-lowering medications make the estimate meaningless because they artificially suppress heart rate. Finally, some expect the 220 − age maximum to be exact; it is an average, and your true maximum heart rate could be 10–15 bpm higher or lower.
When should I not rely on this calculator?
Do not rely on it if you take medications that affect heart rate (beta-blockers, calcium-channel blockers), have an arrhythmia or pacemaker, or have a thyroid condition, because resting heart rate no longer reflects fitness in those cases. It is also unsuitable for children and for elite athletes who need precise figures for training zones — they should use a graded exercise test with gas analysis or a validated submaximal field test such as the Cooper 12-minute run or a beep test. If you are starting exercise after a long break or have known heart disease, talk to a clinician before using heart-rate-based estimates to set training intensity.