Race Time Predictor
Predict your finish time for any race distance based on a recent performance.
About Race Prediction Models
Riegel Formula
The classic formula by Peter Riegel (1977): T2 = T1 × (D2/D1)^1.06. Simple and widely used, but tends to underpredict longer distances.
Cameron Formula
An improved model with distance-specific fatigue factors. More accurate for ultra-marathon distances.
Daniels VDOT
Based on Jack Daniels' VDOT system. Calculates your VDOT from the input race and predicts times for equivalent efforts at other distances.
Which model should I use?
Short to short distancesModels are most accurate when predicting similar distances. Use any model.
Short race → MarathonThe Riegel formula often overpredicts marathon times from short races. Use Daniels VDOT or Cameron for better accuracy.
Well-trained runnersHighly trained runners tend to slow less at longer distances. The Riegel formula may be slightly pessimistic.
General fitness runnersFor recreational runners, Riegel tends to give reliable predictions across a wide range of distances.
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