CardioCalculator
Running Pace Calculator
Convert a distance and time into pace per km and per mile, with equivalent times at every race distance.
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About the predictions
Riegel’s formula assumes you are equally trained for every distance. In practice, marathon predictions from a 5K time run optimistic unless you have actually done the long-run mileage, so treat the marathon row as a ceiling, not 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, the equation behind the equivalent-times table.
- 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.