Predict Your Half marathon Time From a 5K
Ran a 5K lately? Enter your time to see what it predicts for the Half marathon, plus the pace you would need to hold.
Pace in
Predicted Half marathon time
1:43:30
That is 7:54 per mi.
How a 5K predicts your Half marathon
The prediction uses Riegel's formula, which scales your time by the ratio of the two distances raised to the power 1.06. It assumes you have trained for the longer effort. Going from a shorter race to a longer one, the prediction is only as good as your endurance base, so treat it as a target to train toward rather than a promise.
Want the full picture? The race pace predictor shows every distance at once and prints a pace band for race day.