How the race predictor works
Watshoo uses the Riegel performance model to scale race time by distance. It is most useful when the input result is recent and represents a hard race effort.
Race tools
Race Time Predictor
Enter a recent race result to estimate equivalent performances and practical training paces.
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How the training paces work
Training paces use the Daniels VDOT equations to estimate current aerobic fitness from your race result, then convert that fitness into practical intensity targets. Easy pace is shown as a range; faster sessions are narrower targets.
These are training guides, not laboratory measurements. Train from current fitness rather than goal fitness, and adjust for heat, hills, fatigue and surface.
How accurate are race predictions?
Predictions are estimates, not guarantees. Longer-distance results depend heavily on endurance training, fuelling, course profile and weather. A strong 5K can indicate marathon potential, but only marathon-specific preparation makes that potential realistic.