Race Time Predictor
The Riegel formula predicts finish times at other distances from one recent race, assuming similar training and conditions.
Enter your details above and the result will appear here.
How to use
- Choose the distance of your recent race.
- Enter your finish time.
- Predicted times for the other standard distances appear instantly.
Note
Uses the Riegel formula: T2 = T1 x (D2 / D1)^1.06. Predictions assume endurance training matched to the target distance — a 5K time alone will over-predict marathon performance without long-run training. Estimate only — not medical advice.