Health & Fitness
Half to Full Marathon Equivalent Calculator
Project a marathon finish time and pace from a half-marathon result using the Riegel exponent.
Preparing your result…
What this calculator does
Calculates Half to Full Marathon Equivalent Calculator using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
T₂ = T₁ × (d₂ ÷ d₁)^1.06
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • Riegel extrapolation from half to full marathon: predicted full time=half-marathon time×(full distance/half distance)^b=half time×2^b for exact 2:1 distances.
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • b is an explicit empirical fatigue exponent, not a guaranteed personal value. Similar conditions, current endurance preparation and genuine race performance matter. Require positive time and distances; this is a prediction with error, not a promised finish time.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Half-marathon time (minutes) | Fatigue exponent (exponent) | Projected marathon time |
|---|---|---|---|
| Worked example | 105 | 1.06 | 3h 39m |
| Half the amounts | 55 | 1.01 | 1h 51m |
| Double the amounts | 210 | 1.15 | 7h 46m |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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