VDOT is Jack Daniels' fitness score, a 'pseudo VO2max' that blends your aerobic capacity with running economy into one number derived from race performance. A higher VDOT means faster training and racing paces across all distances.

Is VDOT the same as a lab VO2max?

Not exactly. A lab measures oxygen uptake directly. VDOT is estimated from a race result and reflects both your true VO2max and how efficiently you run, so two athletes with the same lab VO2max can have different VDOTs.

How is VO2max estimated from a race?

The tool computes your average velocity, estimates the oxygen cost of that pace, then divides by the fraction of VO2max you can sustain for the race duration. Both relationships come from Daniels and Gilbert's published equations.

How should I use the training paces?

Run easy days at the Easy pace, long tempo efforts at Threshold, hard 3 to 5 minute reps at Interval, and short fast strides at Repetition. Mixing the zones across a week builds aerobic and speed fitness without overtraining.

Why does a longer race give a different VDOT?

If your endurance is well developed, your VDOT will be similar across distances. A big drop at the marathon usually means a fueling or endurance limitation rather than a lower aerobic ceiling, so it highlights what to train.

Running VO2max Estimator

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Running VO2max estimator

This tool estimates your VO2max — expressed as a VDOT score — from a single race result using Jack Daniels’ running formula. VDOT condenses your aerobic capacity and running economy into one number you can use to set precise training paces. Enter a 5K, 10K, or any race and instantly get easy, marathon, threshold, interval, and repetition paces tailored to your current fitness.

How it works

Daniels and Gilbert’s equations drive the estimate. First, average velocity is computed in metres per minute. The oxygen demand of that pace is:

VO2 = −4.60 + 0.182258·v + 0.000104·v²

The fraction of VO2max you can hold for a race of duration t minutes is:

pct = 0.8 + 0.1894393·e^(−0.012778·t) + 0.2989558·e^(−0.1932605·t)

Your VDOT is then VO2 ÷ pct. To produce each training pace, the tool inverts the oxygen-cost equation at a target percentage of VDOT and converts the resulting velocity back into a pace per kilometre.

Example and tips

A 22-minute 5K gives a velocity of about 227 m/min and a VDOT near 48. From there the tool derives an easy pace, a threshold (tempo) pace, and faster interval and repetition paces. Use a genuine all-out race for the input — an easy run will understate your fitness. Re-test every few weeks to keep paces current.

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