Running Race Predictor & Pace Calculator
Enter a recent race or hard training run and we’ll predict your finish time — and the pace you’ll need to hold — for your next running race.
Predicted finish time
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How the prediction works
The calculator uses Riegel’s formula, the endurance model most running
race predictors are built on: T2 = T1 × (D2 ÷ D1)1.06. It takes
your recent time (T1) over a known distance (D1) and scales it to the target distance
(D2), with the 1.06 exponent accounting for the pace runners naturally lose as races
get longer.
For the best prediction, use a recent all-out run — ideally from the last couple of months and at a distance not too far from your goal race. A 10K or half marathon result predicts a marathon far better than a 5K does, and the formula assumes you’ve done the endurance training the longer distance demands.