Race Time Predictor
Ran a 1500m, 3200m or 5K? Estimate what that effort suggests at another distance. See the expected finishing time and goal pace—plus the assumptions behind the prediction.
Start with a race you've run.
Use recent, all-out race performances. Results are distance-based estimates, not guaranteed outcomes or specific course predictions.
Your recent race result
One race is enough. A second result can help describe your personal endurance pattern.
Your predicted performance
5K result → 10K target
Enter a recent finish time and select a target distance.
Distance-equivalent comparison
Useful for comparing goals across common events. Estimates assume a comparable competitive effort and don't adjust for terrain or surface.
| Race distance | Predicted finish | Pace / km | Pace / mile | Interpretation |
|---|
Times are estimates, not qualification standards, exact performance equivalents, or evidence of track–road surface differences. Larger extrapolations, especially toward the marathon, are less dependable.
How athletes and coaches can use it
You already have a performance. The missing piece is a sensible starting point for a new distance—not a fake promise that one race guarantees another.
Choose a starting goal
Use a recent 3200m or 5K to explore an estimated time for another event. Check it against your training, event experience and fitness.
Compare event readiness
Compare distance equivalents as one input to coaching judgment. A second race may reveal a different endurance pattern, but it is not an independently validated forecast.
Turn a target into splits
Take a realistic goal to the Pace & Split Calculator for checkpoints and a printable race plan. This tool predicts; that tool divides a chosen time into splits.
A transparent distance model
Standard mode uses the classic Riegel model. It predicts how race time changes as distance changes under the assumption of a comparable level of effort and fitness.
Worked example: A 20:00 5K predicts approximately 41:42 for a 10K. This is a general distance-equivalent estimate; a specific runner and course may differ.
Optional two-race mode: When you provide two competitive performances at meaningfully different distances, the tool calculates the observed exponent: k = ln(time₂/time₁) ÷ ln(distance₂/distance₁). It uses that exponent only when it passes explicit plausibility safeguards. Those safeguards are engineering choices, not published guarantees of accuracy. Two performances do not create a clinically or scientifically validated individualized prediction model.
Limits: One well-known study of 2,303 recreational runners found the standard Riegel approach reasonably calibrated through the half marathon but frequently too optimistic for the marathon. A result from a short race should not be taken as a credible marathon goal without relevant endurance preparation. Predictions spanning more than tenfold distance are not presented. Read the research. Original model: Riegel (1981).
Race prediction FAQs
Can a 10:00 3200m predict my 5K?
It can provide a useful starting estimate, assuming comparable fitness and effort. It cannot know your aerobic preparation, pacing, tactics or conditions.
Is this a track-to-road converter?
No. It predicts changes across race distances. It does not apply a track-to-road slowdown or claim that every road course has the same difficulty.
Will using two races always improve the prediction?
No. Two races taken in different seasons, on different course types or at unequal effort levels can produce a misleading personal exponent. The displayed result is a mathematical fit, not a validated improvement in accuracy.
Can I predict a marathon using a 1500m time?
The formula can calculate a number, but it is not a reliable standalone marathon prediction. Marathon preparation, fueling, durability and long-distance experience matter considerably.
How is this different from the Pace Calculator?
This predictor estimates a target finish time from an earlier race. The Pace Calculator calculates checkpoints for a finish time you have already chosen.