Marathon Time Predictor
Predict your marathon finish time from a shorter race result using the Riegel formula.
Predicted Race Times
The Riegel Formula is the most widely used race time prediction model:
T₂ = T₁ × (D₂ / D₁)^1.06
Where:
- T₁ = your known race time
- D₁ = the known race distance
- D₂ = the target race distance
- 1.06 = the fatigue factor
Standard race distances:
| Race | Distance (km) | Distance (miles) |
|---|---|---|
| 5K | 5.0 | 3.1 |
| 10K | 10.0 | 6.2 |
| Half Marathon | 21.1 | 13.1 |
| Marathon | 42.2 | 26.2 |
Important: This formula works best when comparing races of similar training focus. Results assume consistent training. Real-world performance depends on terrain, weather, nutrition, and race-day conditions.