VDOT Calculator

Most runners train at two speeds: too fast on easy days and not fast enough on hard ones. VDOT fixes that. From a single recent race result it gives you a fitness score and, more usefully, the exact paces you should run for each type of session. The calculator above does the math from Jack Daniels' formula.

What VDOT actually is

VDOT is a performance-based estimate of your running fitness. It works backwards from a race result to model your effective VO2max, then forwards again to prescribe paces. The beauty is that it accounts for both your aerobic capacity and how efficiently you use it, so two runners with the same lab VO2max but different economy get different, correct paces.

Enter your most honest recent race, ideally something from 1500 metres up to the marathon, run when you were fit and rested. A race you jogged or one you ran on dead legs will skew the number.

The five paces

The calculator returns five training paces, each tied to a purpose:

• Easy: the bulk of your week. Conversational, builds the aerobic base, aids recovery.
• Marathon: race-specific endurance for longer goals.
• Threshold: comfortably hard, the pace that lifts your lactate threshold. This is your tempo pace.
• Interval: around VO2max, run in repeats of three to five minutes to build your ceiling.
• Repetition: faster still, short and sharp, for speed and economy.

Run each session at its prescribed pace and the structure does the work. The classic mistake is turning easy days into moderate ones, which leaves you too tired to hit the hard paces that actually drive adaptation.

Using it well

VDOT is a snapshot, not a life sentence. Retest with a new race or time trial every few weeks of focused training and your paces will shift with your fitness. Do not chase a higher VDOT by forcing your easy runs faster, that just digs a hole. Let the easy stay easy and let the threshold and interval work raise the number.

To get the most out of your threshold pace, the part of the week that lifts your ceiling, read the tempo run guide.