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What VDOT Means

VDOT is a normalized fitness number created by Jack Daniels (the exercise physiologist, not the whiskey). It captures both your VO2max and your running economy in one figure. The genius of VDOT: you don't need a lab to calculate it. Run any race, plug the time into the formula, and get a number that predicts every other race distance and every training pace you should run.

For the full explanation, see Jack Daniels' VDOT explained. For the broader context of training paces, see the running training plan guide.

The Five Training Paces

The calculator returns five paces. Each one trains a specific physiological adaptation:

  • Easy (E) pace. Conversational. Builds aerobic base, capillaries, fat oxidation. Most of your weekly mileage should be at this pace — about 60-90 sec/mile slower than marathon pace.
  • Marathon (M) pace. The pace you'd race a marathon at right now. Used for marathon-pace long runs and tempo segments in marathon training.
  • Threshold (T) pace. Lactate threshold — "comfortably hard," sustainable for ~1 hour if you raced. Used for tempo runs and cruise intervals. The single most important workout pace for distance racing.
  • Interval (I) pace. VO2max pace — the pace you'd hold for ~11-12 minutes flat-out. Used for VO2max intervals (e.g., 5 × 1000m). Builds the engine that supports threshold pace.
  • Repetition (R) pace. Speed and economy work — faster than VO2max, used for short reps (200-400m) with full recovery. Builds running economy and neuromuscular efficiency.

Why VDOT Beats "Effort"

Without a system like VDOT, runners tend to do two things wrong:

  1. Run easy days too hard. "Easy" feels like jogging and feels like a waste of time. Easy runs drift faster, into the gray zone, defeating their purpose.
  2. Run hard days too easy. Intervals at "hard" effort tend to drift slower than VO2max pace because intuition underestimates what 11-minute race effort actually feels like.

VDOT fixes both. Easy is X:XX per mile, exact. Intervals are Y:YY per mile, exact. No drift.

How to Use the Calculator

  1. Pick a recent race. The most accurate VDOT comes from a race in the last 6 weeks.
  2. Enter the distance and time. Longer races generally give more accurate VDOTs (race-day chaos averages out over longer distances).
  3. Get your paces and predictions. The calculator shows your VDOT, the five training paces, and predicted times for other race distances.
  4. Use the paces in training. Easy runs at E pace. Tempo runs at T pace. Intervals at I pace. Don't drift.

Caveats

VDOT predictions assume:

  • Flat course, cool weather, ideal conditions. Adjust upward (slower) for heat, hills, wind. See heat pace adjustment for warm-weather races.
  • You're trained, not detrained. If you've had time off, the resulting VDOT reflects current fitness, not what's achievable with a few weeks of training.
  • Equivalent fitness across distances. Some runners are naturally stronger at shorter distances; some at longer. Predictions for distances far from your input race are less reliable.

Update your VDOT regularly during a training cycle. Fitness changes; paces should change with it.