Race Time Predictor (Riegel Formula)

Project finish times for new race distances using a recent result and the Riegel exponent. Useful for pacing strategy from 1500 meters up to the marathon.

Enter Your Recent Race

Recent Distance

Finish Time (hh:mm:ss)

Target Distance

Predicted Performance

Projected Finish Time --

Equivalent Pace --

How the Riegel Formula Works

Formula

T₂ = T₁ x (D₂ / D₁)^1.06

Step-by-step

Record a recent race time and its distance.
Select the target distance you want to predict.
Apply the Riegel exponent (1.06) to scale your finish time to the new distance.

Notes

The formula assumes similar fitness and pacing skill. It performs best for endurance events between roughly 1500 meters and the marathon. Adjust expectations for very short races or ultramarathons.

References

Runners Calc race time predictor