Set your goal. Build your race plan. Share it with anyone.
This plans your mile-by-mile splits. Even splits means running the same pace the whole way, the simplest plan. Segments lets you break the race into parts with different paces, like settling in for the first 20 miles and then finishing fast over the last 10K. The marathon punishes a fast start more than any other distance: how you run the first miles usually decides how the last ones feel. Segments let you plan a controlled start instead of banking time.
| Mile | Split pace | Elapsed |
|---|
Predictions use the Riegel formula: T₂ = T₁ × (D₂/D₁)exponent. The standard exponent (1.06) assumes you've done the training for the longer distance - the weekly mileage and the long runs. So the slider is really asking: are you properly trained for it, or are you going to gut it out on shorter-race fitness? Gutting it out means fading late, real-world exponents for undertrained marathoners run as high as 1.12, so slide left. High-mileage runners who hold pace forever sit near 1.04, slide right.
Enter a race you've run (or a goal) and see what it predicts for the other distances. Then slide to match your training: if you race short distances well but skip long runs, slide left, and longer-race predictions get slower.