Running Time Predictor
Predict a race time at another distance from a recent result using the Riegel formula (T2 = T1 × (D2/D1)^1.06). An estimate — it assumes equal fitness and similar course conditions.
Your time for that race
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Predicted time
52:07
That is a pace of 5:13/km for 10 km, predicted from your 5 km time of 25:00.
Predictions get less reliable the further the target distance is from your known result — a 5K predicts a 10K far better than it predicts a marathon. Equal fitness and similar course conditions are assumed.
Formula & source — Riegel formula (Riegel, 1981)
T₂ = T₁ × (D₂ ÷ D₁)^1.06, where T is time and D is distance. Published by Peter Riegel in Runner's World (1981) and validated across race distances. An estimate — it assumes equal fitness and similar conditions.
Estimate, not medical advice. FitCalc results are estimates based on population-average formulas. They are not a diagnosis, a prescription, or a substitute for professional medical advice. If you have a medical condition, are pregnant, or take medication, talk to a doctor or registered dietitian before changing your diet or exercise. FitCalc claims no medical credentials.
Try next: Pace Calculator · 5K Pace Calculator · 10K Pace Calculator