Race time predictor
Use a recent race time to make a rough comparison at another distance.
Model estimate
52:27
Average pace: 5:15 per km
A rough comparison, not a promised finish time or a training prescription. Preparation, course, weather and the distance jump can make the result very different. All inputs stay on this device.
Method: Peter Riegel, Time Predicting, Runner’s World, August 1977 (PDF). This implementation derives total time from the published pace equation; it does not reproduce the article’s tables.
Useful to know
Which formula does this use?
Estimated time = recent time × (new distance ÷ recent distance)^1.0689. The exponent is derived from Peter Riegel’s published 1977 pace model, where pace scales with distance to the power 0.0689. Both distances use the same units.
Why is it only an estimate?
The model compares performances across distances. It does not know your preparation, the course, weather or how hard you ran. A result over a much shorter distance does not demonstrate readiness for a marathon.
Can I use it for sprinting or ultramarathons?
This version is limited to one mile through the marathon, the range discussed in the source article. It deliberately does not extrapolate to sprints or ultras.
Clubs and races near you
The location is only used when you follow one of these search links.