Endurance Training Tools
Free calculators and predictors built on the same models the AthleteOS AI uses internally. No signup, no email gate.
Race Predictor
Predict your finish time from a recent effort.
Plug in a recent race or hard workout. Get a calibrated finish-time prediction across distances using physiological pacing models — not the naive Riegel formula. Free, no signup.
Open tool →VO₂max Calculator
Cooper 12-min run test, with age & sex bands.
Run as far as you can in 12 minutes. Get your VO₂max (mL/kg/min) plus a fitness category band by age and sex, using the Cooper 1968 formula validated against treadmill gas-exchange.
Open tool →FTP Calculator
20-minute test → cycling FTP, W/kg, and zones.
Enter your 20-minute average power. Get FTP, W/kg, and a complete Coggan power-zones table (Z1–Z7). Implements the Allen & Coggan 0.95 multiplier from Training and Racing with a Power Meter.
Open tool →VDOT Pace Calculator
Daniels VDOT score + E/M/T/I/R training paces.
Enter a recent race result. Get your Daniels VDOT and Easy / Marathon / Threshold / Interval / Repetition paces in km and miles. Implements the Daniels Running Formula 3rd-edition polynomial regressions directly.
Open tool →TSS Calculator
Coggan Training Stress Score for any cycling workout.
Compute Training Stress Score from duration + IF, or from duration + NP + FTP. Returns the standard load category band (recovery / low / moderate / high / very high).
Open tool →