Race time predictor
Enter one recent all-out result and see what it suggests over other distances.
A recent result
Predicted times
| Distance | Time | Pace |
|---|---|---|
| 1 mile | 7:22 | 4:35 /km |
| 5 km (your result) | 25:00 | 5:00 /km |
| 10 km | 52:45 | 5:17 /km |
| Half marathon | 1:57:55 | 5:35 /km |
| Marathon * | 4:08:48 | 5:54 /km |
* Outside the 3.5–230 minute range where Riegel found the formula holds. Treat these as rough.
Assumes equal training for each distance and similar conditions. Longer races also need the endurance and fuelling to go with the speed.
How it works
Riegel's endurance formula: T₂ = T₁ × (D₂ / D₁)b, using his own fatigue exponent for each sport (Riegel 1981).
Limits
Riegel found the formula holds for efforts of roughly 3.5 to 230 minutes. Longer predictions assume you've trained the endurance (and fuelling) for that distance. More in the methodology.