How to use it

Pick a recent performance that reflects your current fitness: an official race result or a time trial over a measured course. All-out efforts give the model its best input.
Choose the distance — use the preset menu or enter a custom distance in miles or kilometers.
Enter the finish time and read your VDOT estimate.

The math

The calculator implements the Daniels-Gilbert equations published with Jack Daniels' Daniels' Running Formula. The model combines two ideas: the oxygen cost of running at a given speed, and the fraction of maximum oxygen uptake a runner can sustain for a given duration.

First, velocity in meters per minute: v = distance (m) ÷ time (min).

The estimated oxygen cost of that pace, in ml/kg/min:

cost = −4.6 + 0.182258v + 0.000104v²

The sustainable fraction for a duration of t minutes:

fraction = 0.8 + 0.1894393·e^(−0.012778t) + 0.2989558·e^(−0.1932695t)

The VDOT estimate is cost ÷ fraction, displayed to one decimal.

Worked example: 10 kilometers in 48:12:

Time is 48.2 minutes, so v = 10,000 ÷ 48.2 ≈ 207.5 m/min
Oxygen cost ≈ −4.6 + 37.81 + 4.48 ≈ 37.69 ml/kg/min
Sustainable fraction ≈ 0.902
VDOT ≈ 37.69 ÷ 0.902 ≈ 41.8 ml/kg/min

How to read the number

This is a performance estimate, not a laboratory measurement. A gas-exchange test measures your maximal oxygen uptake directly; VDOT infers a fitness number from a race result. The two are related but not identical.
Compare like with like: similar distances, similar conditions, honest efforts.
Trends across several reliable performances tell you more than any single figure — and the same runner can produce different values at different distances, because the model simplifies real physiology.
GPS distance or watch "moving time" can quietly bias the input. Certified courses and official times fit the model best.

Limitations and safety

A performance model is not a clinical measurement, a training prescription, or a test of heart, lung, or overall health.
Never force an unsafe pace to match a predicted number, and never push through pain, chest discomfort, faintness, or unusual breathlessness.
Seek individualized advice before hard testing if you have symptoms, a relevant medical condition, are pregnant, have recently been ill or had surgery, or are returning after a long layoff.
The equations extrapolate from a simplified speed-duration relationship, so very short, very long, or non-running efforts may not fit the model.

Medical note: this page provides general educational information, not individualized medical advice — see our medical disclaimer.

Sources

Daniels' Running Formula, 4th edition (Human Kinetics), for the VDOT performance framework.
ACSM's Guidelines for Exercise Testing and Prescription, for exercise testing and screening context.
Cleveland Clinic — What Is VO2 Max?, for how direct measurement differs from estimation.

More runner tools

Running Pace Calculator — solve pace, time, or distance.
BMI Calculator — CDC adult categories and healthy weight ranges.
All runner tools

VO2 Max Calculator