Marathon Finish Predictor
Predict a longer race finish time from a recent shorter race using the Riegel formula.
Quick answer: enter your details below and click Predict My Finish — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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How to use
- Enter your recent race distance in kilometres.
- Enter that race finish time in minutes.
- Pick your target race and click Predict My Finish.
About this tool
Enter a recent race distance and finish time, then pick a target distance. The tool applies the Riegel formula, which scales time by the distance ratio raised to 1.06, and shows an estimated finish in hours and minutes. This is an estimate, not a guarantee: course profile, weather, and training all move real results away from any prediction.
Frequently asked questions
Is the prediction guaranteed?
No. It is an estimate from one formula; hills, heat, and training can shift a real finish by many minutes.
Why 1.06?
That exponent is the standard Riegel value used for endurance running predictions, balancing fatigue over longer distances.