Race Time Predictor

This race time predictor lets you input a recent race time and distance, to see what you should be capable of at another distance. It is based on a formula devised by Pete Riegel, a research engineer, and has been widely used for over 20 years. The calculator is less accurate for times below three and a half minutes and above four hours. It assumes that you’ve done appropriate training for the distance and don’t have a natural significant bias towards either speed or endurance. This calculator has some additional features above what are available on other sites in that it allows you to predict how weight changes will affect your next race, which is based on this research.

This calculator has an additional experimental feature to estimate mountain running paces based on a pace handicap.

The calculator will also estimate your training paces for key workouts when training for both a 5k and a marathon.