McMillan Running Pace Calculator

You enter one recent race result, a distance and a finish time, and the calculator does two things. First it projects equivalent finish times across the standard distances (5K, 10K, 10 mile, half marathon, marathon) using Pete Riegel's endurance formula, T2 = T1 times (D2 divided by D1) to the power of 1.06. Then it derives training paces from those equivalents. The faster your input race, the faster every projected time and training pace becomes.

Each zone is anchored to the equivalent race pace at the distance that physiologically matches it. Easy and recovery runs sit about 60 to 90 seconds per mile slower than your equivalent marathon pace, and long runs about 30 to 75 seconds per mile slower. Tempo (threshold) pace falls between your 10 mile and half marathon equivalent paces, and interval (VO2max) pace falls between your 3K and 5K equivalent paces. Every zone is shown as a range, not a single exact number.

The Riegel model is most reliable within roughly half to double your input distance. A 10K predicted from a 5K is usually close, while a marathon predicted from a 5K tends to read optimistic because the formula does not account for fueling, heat, or the extra endurance a marathon demands. Treat longer projections as a ceiling on a perfect day, not a guarantee.

Use your most recent all-out race at a distance close to the races you are targeting. A recent 10K is a strong input for 5K through half marathon goals, and a recent half marathon is better for marathon planning. Re-run the calculator after each new race or every 6 to 8 weeks so your paces track your current fitness instead of an old result.

Yes. You can enter your race distance as a named event (5K, 10K, half, marathon) or as a custom value in miles, kilometers, or meters. Every equivalent time and training pace is shown in both minutes per mile and minutes per kilometer, so you can read the output in whichever unit your watch uses.

No. This is an estimate to help you set sensible paces, not a personalized training plan or coaching advice. Your real paces depend on terrain, weather, recovery, and how your training is structured, so adjust by feel and consult a coach for an individualized program.