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Race Time Predictor

Predict your time at any distance from a recent race.

Details

Known distance

Unit

Known time — hours

minutes

seconds

Predict distance

Predicted time—

Predicted pace—

Method—

Estimates only — not medical advice.

We use Riegel's formula: T2 = T1 × (D2 ÷ D1)^1.06. It predicts a longer/shorter race from one you've run, assuming similar training and conditions.

Most accurate when the prediction distance is close to your known race and you've trained for it.

Train smarter with our other free fitness calculators.

Good to know

How does it work?

Riegel's endurance formula scales your time by distance to the 1.06 power.

Is it accurate?

Good for nearby distances with proper training; long extrapolations are rougher.

What distances?

Any — 5K, 10K, half (13.1 mi), marathon (26.2 mi).

Does terrain matter?

Yes — hills, heat and fatigue affect real results.