Recent race distance
Your time
hrs
min
sec
Your predicted times
Sources & method
Uses the Riegel formula: T₂ = T₁ × (D₂ / D₁)¹·⁰⁶, from Pete Riegel, "Athletic Records and Human Endurance" (American Scientist, 1981).
Predictions assume comparable conditions and appropriate training for the longer distance — a marathon prediction from a 5K is optimistic without the mileage to back it up.