VDOT calculator
Enter a recent race, get your VDOT, equivalent times and training paces.
What is VDOT?
VDOT is a number from the running system of Jack Daniels, an exercise physiologist and coach, that rates how well you run, not how big your lungs are. You get it by asking: what oxygen uptake would a runner need to hold my pace for as long as I held it? That makes it an “effective VO2max” taken from a race result rather than from a lab test, so it also reflects how economically you run. Two runners with the same lab VO2max can have different VDOT values. Use it to compare races at different distances and to set training paces.
How is VDOT calculated from a race?
Two equations by Daniels and Gilbert do the work. The oxygen cost of running at a speed v (meters per minute) is VO2 = −4.60 + 0.182258 × v + 0.000104 × v², in mL of oxygen per kg per minute. The share of your VO2max you can sustain for a race that lasts t minutes is 0.8 + 0.1894393 × e^(−0.012778 × t) + 0.2989558 × e^(−0.1932605 × t). VDOT is the oxygen cost divided by that share. The share is about 100 percent for a race of eleven minutes, higher for shorter ones, and falls toward 80 percent for very long ones (it is 95 percent at 20 minutes and 82 percent at three hours).
Worked example: a 20:00 5K
A 5K in 20:00 is a speed of 250 meters per minute. The oxygen cost is −4.60 + 0.182258 × 250 + 0.000104 × 250² = 47.46 mL/kg/min. For a 20-minute effort the sustainable share is 0.953. VDOT = 47.46 ÷ 0.953 = 49.8. The same fitness predicts a 10K in 41:28, a half marathon in 1:31:50 and a marathon in 3:11:17. Riegel’s formula gives 3:11:49 for the marathon from the same 5K, about 32 seconds apart: for nearby distances the two methods agree closely.
What are the training paces for?
They come from the same equation, run backward: pick a share of your VDOT and solve for the speed that costs that much oxygen. Daniels puts easy running at 59 to 74 percent, threshold (“comfortably hard”) at about 88 percent and interval training at about 98 percent. For VDOT 49.8 the calculator gives easy 7:54 to 9:28 per mile, threshold 6:52 per mile (4:16 per km) and interval 6:18 per mile (3:55 per km). Daniels’ printed tables are rounded, so they can differ from the calculator by a few seconds.
Is the marathon prediction realistic?
Only if you trained for a marathon. The prediction says what your fitness would allow at that distance, not what a 5K runner who has never run beyond ten miles will run. The long run, fueling and pacing all matter. Treat a prediction for a distance much longer than your race as a ceiling, and use a recent race at a distance closer to your goal when you have one.
How do VDOT and Riegel’s formula differ?
Riegel’s formula, T₂ = T₁ × (D₂ ÷ D₁)^1.06, is a single power law fitted to world records and needs only the two distances. The VDOT model builds in the physiology: the cost of running faster and the fall in the share of VO2max you can hold as the race gets longer. From a 20-minute 5K they differ by 14 seconds at 10K, 10 seconds at the half marathon, 32 seconds at the marathon and 10 seconds at the mile; they can drift further apart for slower or faster runners. The table above shows both so you can see the spread.
Which race should I enter?
A recent all-out effort on a fairly flat course in mild weather. A slow race, a hilly course, heat or a stop at an aid station will understate your VDOT. The model covers efforts between about 3.5 minutes and a few hours; this page refuses anything outside 3.5 minutes to 10 hours.
Limits of this method
VDOT assumes a maximal effort on a flat course in decent conditions; heat, hills or wind cut your pace without changing your fitness, so the number understates you. Because it is built from a race rather than a lab test, it also folds in running economy and race-day pacing, so it should not be read as a measured VO2max. The printed tables in Daniels’ book are rounded to whole seconds and tenths of a VDOT; this calculator uses the underlying equations directly. The training shares (59 to 74, 88 and 98 percent) are Daniels’ definitions of the intensities, not laws of physiology: the pace at which a given runner’s blood lactate starts to climb varies from person to person.
Common mistakes
The commonest mistake is entering a goal time rather than a time already run, which makes the VDOT a wish. Another is mixing a track mile with a road marathon and expecting one VDOT to predict both without any race-specific training. Runners also use interval pace for “as fast as possible”; it is a hard but controlled effort sized for repetitions of up to about five minutes, not a sprint. Finally, VDOT changes as you train: re-test after a block of training instead of keeping last year’s value.
Sources: Daniels J, Gilbert J, Oxygen Power: Performance Tables for Distance Runners (1979), and Daniels J, Daniels’ Running Formula (Human Kinetics), for the oxygen-cost and sustainable-share equations and the training intensities (easy 59–74%, threshold about 88%, interval about 98% of VO2max); the equations were checked against three independent published descriptions and against the VDOT 50 reference points (a 5K in 19:57 gives VDOT 50.0; threshold pace for VDOT 50 is 6:51 per mile). Riegel PS, “Athletic records and human endurance,” American Scientist 1981;69:285–290. This site has not read Daniels’ printed tables and does not reproduce them. Related: race time predictor (Riegel only), pace calculator, VO2 max calculator, target heart rate calculator.
For general information only — not medical advice. Talk with your doctor before starting or changing a hard training plan. How we check our calculators.