Predict Race Performance Based on Races at Other Distances

When predicting marathon performance based on times from shorter races, be aware that some calculators will predict an overly optimistic finish time for most runners:



I did a survey of runners on the old Runners World Online forum to find out which running calculators gave them the most accurate predictions.  The results were all over the place and it became obvious to me that what was needed is a calculator that can take into account the individual endurance level of runners when making predictions.


As a result, I created the following calculator which uses an adjustable version of the Riegel formula. When using a single predictor race you manually select your estimated endurance level, but if you put in two different predictor races it will estimate your endurance level for you (the two races should be different distances).  Download spreadsheet:

Other Calculators

Heart Rate (Download Spreadsheet):


Input two out of three variables (Distance/Time/Pace and calculate the third):


Run/Walk Calculators:


Track Calculator (Calculates distances, lap splits, pace, etc.):


Calculate Road Grade Based on Distance and Altitude Gain or Loss:


Nutrition Calculator:


WMA Age Grading (See how you rank):


WMA Notes:
100% = Approximate World Record Performance
90%+ = World Class Performance
80%+ = National Class Performance
70%+ = Regional Class Performance
60%+ = Local Class Performance