Race Time Predictor
Predict your 10K, half marathon, and marathon times from a known 5K time using the Riegel formula.
Predicted Race Times
Race time prediction uses the Riegel formula, one of the most widely used methods for predicting race performance.
Formula:
T2 = T1 × (D2 / D1)^1.06
Where:
- T1 = Known race time
- D1 = Known race distance
- D2 = Target race distance
- 1.06 = Fatigue factor (accounts for slowing over longer distances)
Standard race distances:
- 5K = 5 km (3.1 miles)
- 10K = 10 km (6.2 miles)
- Half Marathon = 21.0975 km (13.1 miles)
- Marathon = 42.195 km (26.2 miles)
Note: These are estimates. Actual times depend on training, weather, course elevation, and race-day nutrition.