Race Time Predictor
Predict finish times for 5K, 10K, half marathon and marathon from a recent race result using Riegel and Cameron formulas, with required pace tables and confidence notes.
Accepted range: 1.03–1.12. This personal estimate is kept separate from the three published models and their median.
| Race | Distance | Riegel 1981 | Cameron 1998 | Daniels / VDOT | Three-model median | Personal (1.06) | Riegel pace / km |
|---|
Riegel 1981: T₂ = T₁ × (D₂ / D₁)1.06. The original paper covered endurance performances lasting about 3.5–230 minutes.
Cameron 1998: T₂ = T₁ × (D₂ / D₁) × f(D₁) / f(D₂), where f(d) = 13.49681 − 0.000030363d + 835.7114 / d0.7905 and d is in meters.
Daniels–Gilbert 1979: the known result is converted to VDOT with the published oxygen-demand and sustainable-fraction equations, then numerically inverted for each target distance.
Plan the pace: Pace calculator | estimate fitness: VDOT calculator | train intensity: Heart rate zones.
How to use
Enter a recent all-out race by finish time or pace. Compare the three published models, use the median as a compact summary, and treat low-confidence long-distance extrapolations as scenarios rather than promises.
Race Time Predictor helps athletes and everyday trainees get a clear, actionable number they can use in the gym, on the road or in the pool — without uploading any data. All calculations run locally in your browser.
Use the presets to learn the expected inputs, then adjust for your own session. Export or share the result when you want a training log or a quick plan for your next workout.
FAQ
Is my data uploaded?
No. Inputs stay in your browser. Optional session history uses localStorage on this device only.
Is this medical or coaching advice?
No. It is a free educational calculator. Consult a qualified coach or clinician for personalised programmes, especially if you have injuries or health conditions.
Can I share or export the result?
Yes. Most pages support copy, CSV download and a shareable result image so you can keep a log or send the plan to a training partner.
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