Marathon Time Predictor
Predict race time from a recent result (Riegel).
Inputs
Loading calculator…
Calculating…
Was this helpful?
Formula
T₂ = T₁ × (D₂/D₁)^1.06
Riegel formula extrapolates performance across distances with fatigue exponent 1.06.
Worked example
Half marathon 1:45 often predicts full marathon near 3:40 — individual prep varies.
Where this can give the wrong answer
- Exponent 1.06 is empirical — flat courses only.
- Heat and hills skew predictions.
- Requires race-specific training for the target distance.
FAQ
- Longer distances fatigue more than linear scaling — exponent captures diminishing speed.