VDOT calculator
Enter a recent race to get your VDOT, the fitness score behind Jack Daniels’ training system, with the five training paces and race times that go with it.
Training paces
Equivalent race times
What VDOT measures
VDOT is a single number for your current running fitness, worked out from a race. The official VDOT O2 app describes it as a score that represents your current running fitness, and it sets every training intensity from that score (V.O2).
The number comes from Jack Daniels’ 1979 performance tables, Oxygen Power, which combine the oxygen cost of running at a given speed with how long you can hold a given share of your VO2max (Sean Langan). It looks like a VO2max reading, but it’s built from race results rather than a lab test, so it measures how well you race, not just the size of your aerobic engine.
The five training paces
VDOT O2’s own guide to the paces lays out what each one is for (V.O2).
Easy. Most of your running, at a conversational effort of about 65 to 79 percent of your maximum heart rate. It builds the base the harder sessions rest on, and the easy run guide covers why slower is the point.
Marathon. Your predicted marathon race pace, at about 80 to 90 percent of max heart rate, for rehearsing race conditions or finishing a long run.
Threshold. Comfortably hard, at 88 to 92 percent of max heart rate, and close to the pace you could race for about an hour. It’s the pace for tempo runs and cruise intervals.
Interval. Hard but not all-out, at 98 to 100 percent of max heart rate, in repeats of three to five minutes. It’s roughly the pace you could race for 10 to 15 minutes, and it trains your aerobic power.
Repetition. Your current mile race pace, run as short repeats with full recovery and relaxed form, to build speed and economy.
How this calculator works
It uses the two equations behind Daniels’ tables, one for the oxygen cost of running at a given speed and one for the share of VO2max you can sustain for a given time. Your race time gives your VDOT, and the paces come back out of it. Easy covers the speeds that ask for 59 to 74 percent of your VDOT, threshold sits at 88 percent and interval at 97.5 percent. Marathon pace is your predicted marathon run evenly, and repetition pace is your predicted mile.
Getting an accurate VDOT
Start from a race that shows your current fitness. VDOT O2 recommends a recent result that accurately represents where you are now (V.O2), so pick an all-out effort on a reasonably flat course in normal weather. A race run in heat, on hills or as a workout will set every pace too slow.
Be careful predicting up in distance. Every prediction from a shorter race assumes you’ve trained for the longer one. In a study of 2,303 recreational runners, the Riegel formula, which predicts much the same as VDOT, gave marathon times at least 10 minutes too fast for half of them (Vickers and Vertosick, 2016). The race time predictor adjusts the marathon for your weekly mileage.
Update it after each race. If your paces start to feel too easy or too hard, VDOT O2’s advice is to update your VDOT rather than force the old numbers (V.O2).
Putting the paces to work
The 18-week half marathon plan sets every workout from a recent race the same way, and the Pace Lab turns any goal time into splits, from the 5K to the marathon.
