CardioCalculator
Race Time Predictor
Predict your time at another distance from a race you have already run, by two methods side by side.
Why two methods
Riegel fits a single curve to world records; Daniels’ VDOT works through the oxygen cost of running. They agree closely up to the half marathon. Both assume you are trained for the distance you predict, so from a 5K time the marathon row is a ceiling rather than a plan.
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Formula sources
- Riegel, P.S. (1981). Athletic records and human endurance. Am Sci 69(3).T₂ = T₁ × (D₂/D₁)^1.06.
- Daniels, J. (2014). Daniels' Running Formula, 3rd edition. Human Kinetics.Book. The VDOT equations behind the second column.
- Vickers, A.J. & Vertosick, E.A. (2016). An empirical study of race times in recreational endurance runners. BMC Sports Sci Med Rehabil 8(1).Found Riegel's exponent slightly optimistic for the marathon in recreational runners.