Race Time & Pace Predictor

Enter a recent run and we’ll estimate your times and paces at other distances using the Riegel formula. You can switch between standalone and triathlon off-the-bike predictions.

My input time is:

This tells the calculator whether to treat your result as a fresh run or a triathlon/brick run. It converts between them using an ~12% slowdown for off-the-bike running.

Advanced options

Show predictions as:

Off-the-bike mode applies an ~12% slowdown to approximate typical triathlon run splits vs standalone running.

1.06

Higher values predict more slowdown as distance increases; lower values give more conservative fatigue.

Based on Peter Riegel’s time–distance equation for endurance events. Predictions assume similar conditions, terrain and training.