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Race Time Predictor

Estimate your 5K, 10K, half and full marathon times from a recent race.

Your finish time

How the prediction works

Predictions use the Riegel formula, T2 = T1 × (D2 ÷ D1)1.06, published by Peter Riegel in 1981. It assumes you have trained for the longer distance.

Treat the result as an estimate. It tends to be optimistic for the marathon if your weekly mileage is low, and less reliable when the target is more than about four times your known distance. Heat and humidity, common in Kerala, also slow most runners.