Race Time Predictor
Enter a recent race time to predict your finish time at any distance using three proven formulas: Riegel, Cameron, and Vickers-Lloyd.
How race prediction works
Riegel formula: T₂ = T₁ × (D₂/D₁)^1.06. Exponent 1.06 accounts for physiological slowdown at longer distances. Works best for 2-3× distance range from known race. Example: 20-min 5K → ~41-min 10K.
Frequently asked questions
How accurate are the results?
Formulas used here are validated in population studies but cannot account for individual genetics, body composition, or medical conditions. Treat results as a starting point, not a medical diagnosis.
Should I consult a professional?
If you have specific health concerns, existing conditions, or are planning significant lifestyle changes, consult a qualified healthcare provider (doctor, dietitian, physiologist).
How often should I recalculate?
Recalculate when your weight changes more than 5%, activity level shifts significantly, or every 3-6 months for routine monitoring. Results are snapshots — your body changes daily.
About the Race Time Predictor
Predict your 5K, 10K, half-marathon, and marathon times from any recent race using the proven Riegel formula. Works for all distances and paces. The tool runs entirely in your browser, so nothing you enter is uploaded or stored.
How to use the Race Time Predictor
- Known race distance — enter your known race distance.
- Your time (format: mm:ss or h:mm:ss) — your your time in format: mm:ss or h:mm:ss.
- Prediction formula — enter your prediction formula.
Last updated
For general wellness information only, not medical advice — see our disclaimer.