Race Time Predictor
From your last race to your next goal.
The Riegel formula assumes you slow down a little as the distance grows. It works best between 3 km and the marathon and assumes you trained for the longer distance.
Formula: T2 = T1 × (D2 ÷ D1)^1.06
Results are estimates for general information, not medical or financial advice.
How it works
- Enter your values The result updates as you type.
- Switch units if needed Metric or US units, where it applies.
- Read the result Nothing is stored or sent anywhere.
FAQ
Is it free?
Yes. No account, no limits.
Is my data stored?
No. The calculation happens in your browser and nothing is sent to a server.