VO2max calculator from your race time

Enter one recent all-out race or time trial. You get an estimate of your running VO2max (in ml/kg/min) and the times that same fitness predicts at the mile, 5K, 10K, half marathon and marathon.

How the estimate works

Jack Daniels and Jimmy Gilbert (Oxygen Power, 1979) published two equations from lab testing of runners. The first gives the oxygen cost of running at a given speed: VO2 = −4.60 + 0.182258·v + 0.000104·v², with v in metres per minute. The second gives the share of VO2max you can hold for a race lasting t minutes: %max = 0.8 + 0.1894393·e^{−0.012778·t} + 0.2989558·e^{−0.1932605·t}. Dividing the first by the second turns any race result into an estimated VO2max.

A 25:00 5K, for example, is 200 m per minute. That costs about 36.0 ml/kg/min of oxygen, and a 25-minute effort can be held at about 94% of max, so the estimate is about 38.3. Equivalent times are found by searching for the time at each distance that gives the same number.

5K times and estimated VO2max

The equivalent times are a little more conservative than the Riegel race time predictor for longer races, because the Daniels & Gilbert model assumes your share of VO2max drops faster over long durations. Both assume you're trained for the distance.

Lab VO2max vs. this number

A lab test measures the most oxygen your body can use. A race-based estimate measures how fast you actually run, so it also folds in running economy, pacing and race-day conditions. Two runners with the same lab VO2max can race very differently, and the race-based number is usually the more useful one for setting training paces. Smartwatch VO2max readings use heart-rate models and often disagree with both, so compare a number only with itself over time.

How to raise it

Consistent easy mileage, weekly threshold work and some 3–5 minute intervals at roughly 5K effort are the reliable levers. See 5K interval workouts and how to run a faster 5K. Re-test every 6–8 weeks with a race or time trial.

Health note: this is general training information, not medical advice. If you're new to exercise, returning from injury, pregnant, or have a heart, lung or other medical condition, check with a doctor or qualified professional before you start a plan or hard workouts. Stop and get help if you feel chest pain, faintness or unusual shortness of breath.