Race Time Predictor
Enter a recent race time to estimate equivalent performances across different distances using the Riegel formula.
Frequently asked questions
What formula does the race time predictor use?
It uses the Riegel model, which predicts time from a known performance using T2 = T1 × (D2 / D1)^1.06.
How accurate are predicted race times?
Predictions work best when the source result is recent and the target distance is similar. Endurance, terrain, weather, and training can change outcomes.
How should runners use a prediction?
Use it to set a provisional goal and pacing range, then refine it using training workouts and race-specific preparation.
Can I predict times for any running distance?
The calculator supports common race distances from 800m to marathon. Predictions between very different distances are less reliable than between similar distances.
What are the limitations of the Riegel formula?
The formula assumes a constant fatigue factor, but individuals differ. Women, older runners, and less experienced athletes may have different endurance decay rates than the model assumes.