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Race Finish Time Prediction from Reference Race (Riegel Formula) Calculator

t₂ = t₁ × (d₂/d₁)^1.06 — Riegel's endurance fatigue constant.

Predicts finish time for a target race distance from a known race result: t₂ = t₁ × (d₂/d₁)^1.06. Commonly used to predict marathon time from 10K.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

s
km
km

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

t₂ = t₁ × (d₂/d₁)^1.06

In depth

Predicts finish time for a target race distance from a known race result: t₂ = t₁ × (d₂/d₁)^1.06. Commonly used to predict marathon time from 10K.