Tools for runners
Running calculators for training and race day
Start with a goal time or a recent result. Choose a tool below to work out pace, training zones, fuel, or a race strategy. You only need an account if you want to save the result.
All tools
Every calculator is free to use. Results update as you enter your numbers.
Pace
Marathon Pace Calculator
Enter a finish time to see the pace per mile or kilometer, plus a full split chart.
OpenCourse
Race Difficulty Analyzer
Estimate how elevation, weather, surface, and altitude could affect your race pace.
OpenPrediction
Race Time Predictor
Use a recent result to estimate finish times at other distances with the Riegel formula.
OpenQualification
Boston Qualifier Calculator
Check your age-group standard and see how much buffer your marathon time has.
OpenTraining
Training Pace Zones
Use a recent race to estimate your VDOT and paces for easy runs, threshold work, and intervals.
OpenFuel
Race Day Fuel Planner
Build a carb, fluid, and sodium plan around your race duration, weather, and fuel preference.
OpenRace strategy
Negative Split Calculator
Turn a goal time into an even or negative split plan, with a pace for each phase of the race.
Open
Race week
MarathonOS
MarathonOS puts your race countdown on your Lock Screen and keeps every race-week checklist on your phone. Checklists and your race report are free for your first race.
