Estimate VO2 max from running times, Cooper test, or resting heart rate methods.
This tool converts one fitness data point into an estimated VO2 max, the standard measure of aerobic capacity in milliliters of oxygen per kilogram of body weight per minute. You pick a route: a 12-minute Cooper test distance, a timed run, or your resting heart rate along with your age. Each route feeds a published prediction equation. The surprise for most users: every method assumes near-maximal effort, and the equations estimate rather than measure - two methods can disagree by several units for the same runner, and only laboratory gas analysis measures VO2 max directly.
A concrete input and expected output from the current implementation.
Input
Cooper test: 2,400 meters in 12 minutes
Expected output
Estimated VO2 max: 42.4 ml/kg/min
The Cooper equation is VO2 max = (distance in meters - 504.9) / 44.73, so 2,400 - 504.9 = 1,895.1, and 1,895.1 / 44.73 = 42.37, rounded to 42.4. The same performance entered into a run-time equation comes out slightly different, because each method uses its own formula.
Run as far as you can in exactly 12 minutes and enter the distance in meters. The estimate comes from the Cooper equation, VO2 max = (distance - 504.9) / 44.73, published from a 1968 study of male U.S. Air Force personnel. It assumes a flat course and an all-out effort: pace yourself wrong, hold back at the end, or run a hilly route, and the number comes out too low.
This route needs no exercise at all. The tool combines your resting heart rate with a maximum heart rate - measured, or estimated from your age - and works from the ratio between them, on the logic that a fit heart pumps more blood per beat, so it beats slower at rest. It is the least precise of the three methods: resting rate should be measured while genuinely rested, and an age-derived maximum is itself an approximation.
Not close enough to be treated as one. A laboratory test measures the oxygen you actually consume during a graded exercise test with gas analysis; these equations predict that value from simpler inputs, typically missing it by several ml/kg/min in either direction. They are fine for tracking whether training is working, not for diagnosing or comparing against precise thresholds.
Because they are different equations built from different evidence: a 12-minute distance, a run time, and no exercise at all, respectively. Differences of several units between methods for the same person are normal, not a bug. Judge progress by repeating one method under the same conditions, not by comparing numbers across methods.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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