Running pace calculator
Pace from a finish time, finish time from a pace, and what that effort predicts for 5K, 10K, half marathon and marathon.
How to use the predictions
Use a recent race or a hard time trial, not a training run. Predictions are most reliable between neighboring distances: a 10K predicts a half marathon well, but a 5K says less about a marathon.
For coaches
In Athelista you can plan intervals at "5K pace" or "tempo", and each athlete's watch gets their own pace from their pace group. See how workouts reach the watch.
Questions
How are race times predicted?+
With Pete Riegel's formula: T2 = T1 × (D2 ÷ D1)^1.06. It assumes you're equally trained for both distances, so marathon predictions from a 5K are often optimistic unless you've done the long runs.
What pace should my easy runs be?+
A common guide is about 80–100 seconds per km (2:10–2:40 per mile) slower than 10K race pace, which is what Athelista uses for easy pace, or by feel in heart-rate Zone 2.
Kilometers or miles?+
Switch units at the top. Race distances stay the same; paces and custom distances change unit.