Race Finish Time Predictor Calculator
Enter a recent race distance and time along with a target race distance to predict your likely finish time at that new distance.
Race Finish Time Predictor Calculator
Predicts your finish time for a target race distance based on a recent race or time trial result, using Riegel's endurance formula.
This calculator applies Riegel's endurance formula — a widely referenced and publicly documented method (Peter Riegel, 1977) that predicts race time at a new distance by scaling a known time by the distance ratio raised to the power of 1.06. It's commonly used by runners to set realistic goal times for an upcoming race based on a recent result at a different distance, though predictions are most reliable when the two distances aren't too far apart.
Example
- With the default values shown above, this calculator returns: Predicted Finish Time ≈ 52.1 minutes.
Frequently Asked Questions
What formula does this use?
It uses Riegel's endurance formula, T2 = T1 × (D2/D1)^1.06, a widely used empirical model for predicting race times at a new distance from a known performance at another distance.
How accurate is this prediction?
It's a well-established estimate that works reasonably well for predicting between similar distances (e.g. 5K to 10K), but accuracy decreases for very different distances (like predicting a marathon from a 5K time), since fatigue and pacing strategy differ more at longer distances.
Sources
- Standard formula, publicly documented method