Race Time Predictor
Enter a race you've finished and see a ballpark time for another distance.
hr
min
sec
Predicted Half marathon time from a 5K
2:08:48
Uses the Riegel formula (T₂ = T₁ × (D₂/D₁)¹·⁰⁶). It's a rough endurance estimate — hills, heat, and training change real results.