Riegel Race Time Predictor
Predict your finish time at a new running distance from a recent race result using the Riegel formula.
How to Use the Riegel Race Time Predictor
- Enter a recent race distance and your finish time.
- Enter the target distance you want to predict.
- Click Calculate to see the predicted time and pace.
Casi d'Uso
- •Setting realistic race targets.
- •Pacing decisions on race day.
- •Comparing performances across different distances.
Formula
T₂ = T₁ × (D₂ / D₁)^1.06. The exponent 1.06 reflects the typical slow-down runners experience as distance increases.
Domande Frequenti
How accurate is the Riegel formula?
Riegel is most accurate when the two distances are reasonably close and the runner has comparable training for both. Extrapolating from 5K to marathon or vice versa is less reliable.
Why 1.06?
Peter Riegel fitted a power law to race data in 1977 and found that for distances between roughly 3 km and the marathon, an exponent around 1.06 gives a good fit across runners of different abilities.
Does it account for training state?
No — the formula assumes you are equally well prepared for both distances. Marathon specialists usually outperform the prediction on longer distances.