Home / Race time predictor
Race time predictor
From a recent race, estimate your time at a target distance (Riegel).
Predicted time—
Predicted pace · per km—
Riegel is optimistic over big jumps (5K to marathon). Treat as an estimate.
What formula is used?
Riegel's formula: T2 = T1 × (D2/D1)^1.06, a well-established race time predictor.
Is it accurate for big distance jumps?
Riegel tends to be optimistic over large jumps (e.g. 5K to marathon) — treat it as an estimate, not a guarantee.
Does it account for terrain or heat?
No — it's a pure mathematical extrapolation from flat, comparable-condition performances.