Race Time Predictor
Predict a running time at another distance using a recent race performance and the Riegel formula.
| Input | Value |
|---|---|
| Known distance (km) | |
| Known time (hh:mm:ss) | |
| Target distance (km) |
How to Use the Race Time Predictor
Enter a recent race distance and finish time, then select the distance you want to predict. The calculator estimates an equivalent performance using a distance-scaling formula.
Practical Example
If you recently ran 5K in 25 minutes, the calculator can estimate a possible 10K or half-marathon time assuming comparable fitness and endurance.
Factors That Affect the Result
Training specificity, endurance, course difficulty, weather, fueling, pacing and how recent the reference race was can all influence prediction accuracy.
Frequently Asked Questions
Is a predicted race time guaranteed?
No. It is a performance estimate, not a guarantee.
Should I use my fastest recent race?
A recent, well-paced effort on a comparable course usually provides the most useful input.
Why can long-distance predictions be less accurate?
Endurance and fueling become increasingly important as race distance increases.