Run Your Next Marathon.
Free Training Tools
View all →Pace Calculator
Calculate splits, finish time, and pace for any distance.
Race Time Predictor
Predict marathon, half, and 10K times from a recent race.
BQ Calculator
Check if your time qualifies for the Boston Marathon.
Training Pace Zones
Get your VDOT and five training zones from Jack Daniels.
Race Day Fuel Planner
Plan carbs, hydration, and electrolytes for race day.
Course Difficulty Analyzer
Score any course on elevation, altitude, heat, and more.
MarathonOS
An iOS app for marathon training. Track runs, follow a plan, prepare for race day.


