Race Time Predictor

The predictor gives an estimate of your time for a given distance using data from your recent races.


Enter the distance and time from a recent race. You can optionally enter a second set of data from another race of a different distance, which will give a better prediction.

Enter the distance you wish to predict and the predicted values will be calculated automatically. See "Additional Information" below for description of Coef.

Recent race data:
Race 1 distance:   Time:
Race 2 distance:   Time:
Predict time for:
Distance:   Coef:
Predicted time: N/A
Predicted pace: N/A /

Additional Information

The estimator uses the following formula devised by Pete Riegel:

T2 = T1 x (D2 / D1)C

D1 = distance you already raced
T1 = time for the known distance
D2 = distance you want to predict the time
T2 = predicted time for the new distance
C = performance degradation coefficient

This formula was first published in the August 1977 issue of Runner's World. Your overall pace slows as you run longer distances. The coefficient (Coef) describes this slow down. A larger value will produce a longer predicted time.

If you enter a second distance, the predictor will automatically make use of this second value to create a personalized coefficient, which will improve the accuracy of the predicted time. You can also type in your own performance factor to adjust the calculation. Typical values are 1.06 to 1.10.