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Running and endurance

Race Time Predictor

Enter a recent race and get realistic predictions for the other distances, with the pace to hold.

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Results
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Prepare your goal with a running coach

Training paces are only useful inside a plan. A running coach builds the weeks, the long runs and the taper for your race.

Running coach Endurance coach Athletic performance coach Training programs

Continue with

Marathon Pace CalculatorThe pace and splits for your marathon goal. Half Marathon Pace CalculatorThe pace and splits for your half marathon goal. VDOT CalculatorYour VDOT and easy, marathon, threshold, interval and repetition paces.

Example

A 22:00 5K predicts a 45:50 10K, a 1:41 half marathon and a 3:31 marathon, if training matches the distance.

Method and formula

Riegel formula (1981): T2 = T1 × (D2 / D1)^1.06, the standard model used by most calculators. VDOT is computed alongside for the VDOT tool.

Limits

  • Predictions from short races overestimate long-race performance when long-run volume is missing.
  • Heat, hills and a poor taper make the prediction optimistic.

FAQ

How accurate are race predictors?

Within a few percent for adjacent distances (5K to 10K, 10K to half). Marathon predictions from a 5K are the least reliable.

What is the best race to predict a marathon?

A recent half marathon, run about 4 to 8 weeks before.

Free educational tool. Results are estimates from published formulas.