Race Time Predictor

Predict your finish time for another distance from a recent race result.

1.06 is Riegel’s value; 1.07–1.08 is more realistic for many recreational marathoners.
Times: 25:00 or 1:50:00.
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Predicted time
Predicted pace
All distances
Even-pace comparison
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Riegel’s Race Prediction Formula

T₂ = T₁ × (D₂ ÷ D₁)^1.06

Pete Riegel published this in 1977 (and in Runner’s World, 1981) from world-record times across distances. The exponent 1.06 captures how pace slows as distance grows.

Worked Example

Tips

Predictions assume you’ve trained for the longer distance. Marathon predictions from short races are often optimistic for newer runners; try an exponent of 1.07 or 1.08.