Marathon Time Predictor
26.2 mi via Riegel. Most accurate from a recent half marathon.
Result
Predicted Marathon
3:28:39
Pace 7:57/mi.
- Base race13.1 mi
- Base time100:00
- Predicted marathon3:28:39
- Pace7:57/mi
Step-by-step
- T₂ = T₁ × (26.22/13.1)^1.06 = 12,519s.
How to use this calculator
- Enter recent race time.
- Read marathon prediction.
About this calculator
Marathon predictor: 26.2 mile race time from recent shorter race. Most accurate from a recent half-marathon — same race-day fitness. From 5K, prediction is optimistic — extrapolation too far ignores marathon-specific endurance. Add 5-10% buffer if your longest training run is below 18 miles. World marathon record: 2:00:35 (Kelvin Kiptum, 2023).
Frequently asked
Half-marathon within 6 weeks. Closest physiology to marathon.
Related calculators
5K Time Predictor (Riegel)
Predict 5K from another race using Riegel formula: T₂ = T₁ × (D₂/D₁)^1.06.
10K Time Predictor (Riegel)
Predict 10K via Riegel: T₂ = T₁ × (D₂/D₁)^1.06.
Half Marathon Time Predictor
Predict 13.1 mi via Riegel.
Race Time Predictor (Riegel formula)
Predict your time at any distance using Riegel's formula T₂ = T₁ × (D₂/D₁)^1.06.
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Lactate Threshold Pace Estimator
LT pace ≈ pace you can hold for 60 min. Estimate from recent race or HR zone.