About this tool
The Daniels Training-Pace Calculator converts a recent race result into the five running training paces from Jack Daniels' Running Formula: Easy (E), Marathon (M), Threshold (T), Interval (I) and Repetition (R). It first derives your VDOT — a VO₂max-style fitness number — then scales it to each training zone. It runs entirely in your browser.
VDOT comes from the race distance D (metres) and time t (minutes): velocity v = D ÷ t; VO₂ = −4.60 + 0.182258·v + 0.000104·v²; and the fraction of VO₂max sustained for that duration is %VO₂max = 0.8 + 0.1894393·e^(−0.012778·t) + 0.2989558·e^(−0.1932605·t). VDOT is VO₂ ÷ %VO₂max. Each zone then targets a fixed fraction of VDOT — E ≈ 0.70, M ≈ 0.84, T ≈ 0.88, I ≈ 0.98, R ≈ 1.05 — and the VO₂-to-velocity quadratic is inverted to get the pace.
The results give minutes:seconds per kilometre and per mile for every zone, so you can build workouts straight from one recent race. Easy runs build aerobic base, Marathon pace is race-specific endurance, Threshold sharpens lactate clearance, Interval develops VO₂max, and Repetition trains speed and economy. This is a training guide, not medical advice.