10K Time Predictor (Riegel)

Predict 10K via Riegel: T₂ = T₁ × (D₂/D₁)^1.06.

Inputs

Result

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How to use this calculator

  • Enter known race distance + time.
  • Read predicted 10K.

About this calculator

Predict 10K race time from a recent shorter or longer race using Riegel's formula. Most accurate when input race is within 2× distance ratio. 5K → 10K is the most reliable prediction (small extrapolation, similar physiology). Marathon → 10K underestimates 10K time (you have more endurance than speed).

Frequently asked

Best base for 10K prediction?+
5K result, recent. Half-marathon also works.
Why is the exponent > 1?+
Doubling distance doesn't halve speed; you slow somewhat. Empirically ~1.06.
Adjustments for course?+
Hilly course: add 1-3% to predicted time. Trail: 5-10%. Heat above 70°F: 1-2% per 10°F.
Daniels VO2max method?+
Alternative: estimate VDOT, predict from VDOT tables (Jack Daniels Running Formula). Similar accuracy.
Untrained for distance?+
Predicting marathon from a 5K when you've never run >10K: unreliable. Need long-run training base.

Related calculators

5K Time Predictor (Riegel)
Predict 5K from another race using Riegel formula: T₂ = T₁ × (D₂/D₁)^1.06.
Half Marathon Time Predictor
Predict 13.1 mi via Riegel.
Marathon Time Predictor
26.2 mi via Riegel. Most accurate from a recent half marathon.
Race Time Predictor (Riegel formula)
Predict your time at any distance using Riegel's formula T₂ = T₁ × (D₂/D₁)^1.06.
VO2 Max from Cooper 12-Min Run
VO2max ≈ (distance in meters − 504.9) / 44.73. Cooper test estimates aerobic fitness.
Lactate Threshold Pace Estimator
LT pace ≈ pace you can hold for 60 min. Estimate from recent race or HR zone.

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