Practical running guide · Finish Line Labs
What a predictor estimates
Finish Line Labs uses a power-law estimate on its homepage: predicted time = known time × (new distance ÷ known distance)^1.06. It is a mathematical extrapolation, not a measurement of current race fitness.
When the model can miss
A fast mile does not automatically imply marathon readiness. Endurance background, training volume, race execution, course profile and fueling affect whether a runner can hold a predicted speed.
How to use an estimate
Treat results as starting points for choosing workouts or tentative goals. Compare estimates with recent longer efforts and update them as your training and race results change.
Try it with your own numbers
Use the relevant calculator to turn these concepts into a pace, split or workout estimate.
Keep in mind
These examples illustrate calculations and general training ideas. Your ideal pace depends on fitness, recovery, health, terrain and conditions. Treat predictions as estimates rather than promises.