Running Performance Predictor


  1. Enter your recent race results below (fields for cumulative up- & downhill height meters are optional: also read the background information):

    Distance (km)Up- & downhill (m)Time (h:mm:ss)

  2. Enter information on your upcoming race below:

    Distance (km)Up- & downhill (m)


Background information

Disclaimer: This running performance predictor uses client-side JavaScript; none of the entered information is transmitted.
The results are provided "as is" − no warranty is given as for your actual upcoming race performance (duh).

The prediction is based on the empirical formulas of Peter Riegel (fatigue factor, commonly assumed 1.06) and of Mervyn Davies (hill factor, commonly assumed 3.3%):

  [Race time] = [1K pace] × [Distance][Fatigue factor] × (100% + ([%Uphill] − 0.55 × [%Downhill]) × [Hill factor])

Especially the fatigue factor depends on personal fitness: Riegel's published value of 1.06 was determined for elite athletes, while larger values (~1.1) apply to most of us "mortals". As a result, the original equation may afford too optimistic estimations for longer-distance (e.g. marathon) finish times. Therefore, this predictor fits the recent race results to derive the personal 1K pace, fatigue factor, and hill factor; default values are taken for the latter factors if insufficient data is provided. The derived performance indicators and the residual variance of the fitted data are used to predict and bracket the finishing time for the target distance. Note that the prediction will be more reliable for an interpolation vs. an extrapolation, and when based on more input data for various distances (three being the bare minimum!). Especially the hill factor is ill-defined unless several results with significant height meters are included. To predict the time for an essentially flat race, better leave the up- & downhill fields at zero; the hill factor will then be neglected to afford a narrower bracket.