Race Time Predictor is a free tool for runners who want to set realistic goals at new distances — without relying on a single formula.
Most race time calculators use a fixed mathematical formula (commonly Riegel's formula) to extrapolate your time from one distance to another. These formulas assume a specific relationship between distances that holds on average, but individual runners vary a lot — some are stronger at longer distances, some drop off quickly, and performance depends on training, terrain, weather, and race-day conditions.
A formula gives you one number. What you actually want to know is: where in the distribution of outcomes am I likely to fall?
Instead of a formula, this tool looks up real runners who ran a similar time to yours at your chosen input distance. It then shows you the full distribution of what those runners achieved at your target distance — the median, the spread, and the full histogram.
You can see whether the times cluster tightly (the distance conversion is fairly predictable) or spread widely (results vary a lot). You can filter by gender and age group to compare yourself specifically to your demographic.
Results are drawn from a large database of real race performances, covering road races, track events, and parkruns across all distances from 100 metres to marathon. The database spans runners of all ability levels, from recreational club runners to competitive athletes, and covers multiple age groups and both genders.
Only real recorded race results are included — no estimated or predicted times.
Results are historical — training methods and race participation patterns change over time. For less common distances (such as 9K or 600m), the database may have fewer matched runners, which can make distributions less representative.
Always treat the output as a guide, not a guarantee.
Try the tool