FREE · SPORTS & TRAINING
Race Time Predictor.
Predict your times from 1,500 m to 50 km from one recent race, with pace per kilometre and per mile.
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How to use Race Time Predictor
Choose the distance of a recent race, enter your time and keep or adjust the fatigue exponent.
How it works
Riegel’s formula T₂ = T₁ × (D₂ ÷ D₁)^1.06.
Example
A 48:30 10 km predicts 23:16 for 5 km and 1:47:01 for a half marathon.
Questions about Race Time Predictor
Is Race Time Predictor free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
Predictions assume suitable training; marathon predictions from short races are often optimistic. Everything is calculated in your browser; nothing you type is uploaded. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.