Running Pace Calculator
Pace (min/km)
5:00
Speed (km/h)
12 km/h
Predicted race times (Riegel)
5K
23:58
10K
50:00
Half
1h 50m 19s
Marathon
3h 50m 00s
FAQ
Running and performance
What is Riegel's formula?
T2 = T1 × (D2/D1)^1.06. Predicts time for distance D2 from a known time T1 over distance D1. Assumes pace is sustainable; pace slows for longer races.
Pace or speed?
Pace (min/km) is intuitive for running: time per km. Speed (km/h) is better for comparisons or cycling.
What is the Riegel formula?
It is the relation that estimates your time over one distance from a run over another, raising the ratio of the distances to the power of 1.06. It allows for pace dropping as the race gets longer.
Is it better to think in pace or in speed?
In running the pace per kilometre is more immediate, because it says how many minutes each kilometre takes. Speed in kilometres per hour stays handy for comparing different sports.
Does the prediction allow for heat and hills?
No, it holds for a flat race in normal conditions, and it assumes training suited to the distance. Climbs, wind and heat all make the real time worse than the estimate.