🏃 Race Time Predictor
Predict 5K to marathon times from a recent race
About this calculator
Runners have long noticed that race performances scale predictably with distance, and physiologist Peter Riegel turned that observation into a formula used worldwide. Enter a recent race result and it predicts your equivalent times from 5K to the marathon. It assumes similar fitness, similar conditions, and proper training for the longer distances.
Tip: Use a recent all-out effort, not a training run. The prediction is only as honest as the input.