VO2 Max Calculator – 15.3 × HRmax/HRrest

VO2 max is the maximum oxygen your body can use per minute per kilogram — the single best measure of cardiorespiratory fitness. This calculator estimates it from heart rates using the Uth-Sørensen-Overgaard-Pedersen formula, 15.3 × HRmax ÷ HRrest, because fitter hearts have a larger gap between their maximum and resting rates. Worked example: a runner aged 35 with a resting heart rate of 55 has HRmax = 220 − 35 = 185, so VO2 max ≈ 15.3 × 185 ÷ 55 = 51.4 ml/kg/min — a good fitness level for that age. The result maps onto categories: below 35 is poor, 35–45 average, 45–55 good, 55–65 excellent and above 65 elite. Measure HRrest right after waking for three days and average it; use a lab or field test to confirm any borderline value.

1. 1

   Enter your heart rates

   Resting HR measured at wake-up and max HR (or age for the 220 − age default)

2. 2

   Get your VO2 max

   The formula returns ml/kg/min instantly

3. 3

   Read your category

   Your score is placed from poor to elite for your age

• 1

  Measure resting HR on three consecutive mornings and average

• 2

  A chest strap beats wrist optics for accurate max HR

• 3

  Values move 2–5 ml/kg/min with a real training block

• Using caffeine-day resting heart rates, which read 5–10 bpm high

• Treating the 220 − age default as personal — real HRmax varies ±12 bpm

• Comparing your score to a different age group’s table

• Testing max HR without a proper graded warm-up