Lunia · Free tools
Marathon Race Predictor
Compare predicted 5K, 10K, half-marathon and marathon finish times.
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Your result
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Enter your details, then calculate to see your result here.
How this calculator works
The Riegel model projects time with T₂ = T₁ × (D₂/D₁)^1.06. This calculator uses the same exponent for every comparison and shows common race distances side by side.
A worked example
Distance: 5 · Distance unit: Kilometres · Finish time: minutes: 30 · Finish time: seconds: 0
- 5K
- 30:00
- 10K
- 1:02:33
- Half marathon
- 2:18:00
- Marathon
- 4:47:44
These are illustrative inputs, not personal recommendations.
Common questions
Why is this slower than simply multiplying my 5K time?
The exponent increases projected time as distance grows, representing a typical reduction in sustainable speed over longer races.
How should I use the result?
The exponent is a population heuristic. A marathon requires specific endurance training, fuelling and pacing; a short race alone does not establish marathon readiness.
Sources & method references
Formula-based results are estimates, not individual medical advice.