Marathon Time Predictor
Predict your marathon or half marathon finish time based on a recent race result using the Riegel formula.
Predicted Race Times
The Riegel Formula predicts race times based on a known performance at another distance:
T₂ = T₁ × (D₂ / D₁)^1.06
Where:
- T₁ = your known race time
- D₁ = the distance of your known race
- D₂ = the target race distance
- 1.06 = the fatigue factor (accounts for slowing over longer distances)
Standard race distances:
- 5K = 3.1 miles (5 km)
- 10K = 6.2 miles (10 km)
- Half Marathon = 13.1 miles (21.1 km)
- Marathon = 26.2 miles (42.2 km)
Example: A 25:00 5K predicts approximately a 1:56 half marathon and a 4:03 marathon.
Note: The Riegel formula assumes similar training and conditions. Proper marathon-specific training (long runs, fueling strategy) significantly affects actual performance.