Use this calculator to predict your time and pace based on a previous race. Enter a race time above, and the calculator will predict your race time. This calculator assumes that you have trained appropriately for the distance

How to predict race times accurately?

The Race Time Predictor Calculator makes use of an equation proposed by Riegel (1981). The equation proposed by Riegel can be accurately used to predict race times from 1mile to Half Marathon, a study conducted in 2016 found that for distances above the Half Marathon it tends to be too optimistic. Read more about Riegel's formula.

What was Riegel's Equation for estimating race times?

T2 = T1 x (D2/D1)^1.06

  • T2 = Goal Race Time
  • T1 = Recent Race Time
  • D2 = Goal Race Distance
  • D1 = Recent Race Distance
  • 1.06 = Riegel's Constant

The effects of Training on calculations

The Race Time Predictor assumes that you have trained adequately for the distance. For example, if you run a 5k in 25min, you can't expect to do a Half Marathon in the indicated time if you haven't trained sufficiently for the distance.

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