Predict Time
Enter a recent race result to predict your marathon potential.
How accurate is this marathon time predictor?
This calculator uses Peter Riegel's widely respected endurance formula, invented in 1977. While it is mathematically sound for endurance athletes, predicting a marathon based on a 5K is inherently difficult because a 5K relies heavily on anaerobic capacity, whereas a marathon is almost purely aerobic.
Caveats to the prediction
If you haven't put in the necessary long runs (the 18-20 milers), this predicted time will be nearly impossible to hit. This calculated time represents what you are capable of assuming you have completed a full marathon training program.
The best race distance to predict a marathon
A Half Marathon is far more indicative of your marathon capabilities than a 5K or a 10K. As a rule of thumb, some coaches simply double your half-marathon time and add 10 to 15 minutes to generate a realistic marathon goal pace.