Enter a recent race result and see predicted times at other distances. Three models: Daniels–Gilbert (VO2max-based, recommended), Riegel (exponent 1.06) and an exponent 1.10 variant that degrades faster as distance grows.
Frequently Asked Questions
Which model should I trust?
Daniels–Gilbert is the most robust across 5K to marathon because it accounts for the fraction of VO2max you can sustain at each duration.
How accurate is it?
Predictions assume distance-specific training. If you trained only for 10K, a marathon prediction will be optimistic.
Why is the 1.10 result sometimes faster?
A larger exponent amplifies the distance change: slower for longer races, faster for shorter ones. Use it as a conservative reference for longer distances.
Gear runners ask about
GPS running watch
Pace, laps and alerts on your wrist
Chest strap heart-rate monitor
More reliable than wrist-based HR
Race day running shoes
Lightweight shoes for tempo and race pace
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