Run race time predictor
Predicted times from 5k to marathon, or the pace a target time needs.
Your result will appear here.
How this is worked out
Riegel's formula
T2 = T1 x (D2 / D1)^1.06, where T is time and D is distance. It assumes you slow by a set proportion as the distance grows.
Cameron's formula
T2 = (T1 / D1) x D2 x (f(D1) / f(D2)), where f(x) = 13.49681 - 0.000030363x + 835.7114 / x^0.7905 and x is the distance in metres. It is Dave Cameron's model.
From your threshold pace
We take off 12 seconds per km to get the 5k your threshold stands for, then predict the other distances from that 5k.
The pace a target needs
Pace = target time / distance. A half marathon is 21.0975 km and a marathon 42.195 km.
What a prediction assumes
That you are as well trained for the new distance as for the one you entered, on a similar course in similar weather, and that you pace it evenly.