Race time predictor
Enter a recent race or time trial. You get a prediction for every other distance, with the pace to run it.
How it works
The predictor uses Riegel’s formula: T2 = T1 × (D2 ÷ D1)^1.06. Double the distance and your time a little more than doubles, because you slow down as you go longer.
It works best between distances you have trained for. Going from 5K to a first marathon takes months of longer runs, and the prediction assumes you have done them. For your first 10K, try the 5K to 10K plan.
Questions
How accurate is a race time prediction?
It’s a good guide when you have trained for the longer distance. Riegel’s formula assumes you have the endurance for the race; for a first half marathon or marathon most people run a few minutes slower than predicted.
What is Riegel’s formula?
T2 = T1 × (D2 ÷ D1)^1.06. It was published by Pete Riegel in 1977 and says that each time you double the distance, your time slightly more than doubles.
What 10K time does a 30-minute 5K predict?
About 1:02:33, with training for the 10K. Use the calculator for your own time.
Let the app do the maths
Run tracks your pace, distance and heart rate on every run, and builds a plan from zero to 5K or 10K that adapts to how you feel.
Download on the App Store