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Race time predictor
Enter a recent race result to predict your time at every other distance.
Predicted from a 5K in 25:00
| Distance | Predicted time | Pace |
|---|---|---|
| 1 mile | 7:31 | 4:40 /km |
| 5K | 25:00 | 5:00 /km |
| 10K | 52:07 | 5:13 /km |
| Half marathon | 1:55:00 | 5:27 /km |
| Marathon | 3:59:47 | 5:41 /km |
How the prediction works
The calculator uses the Riegel formula, the most widely used race predictor: T2 = T1 × (D2 ÷ D1)1.06. The 1.06 exponent captures how pace slows as distance grows.
Predictions are most accurate between nearby distances, such as 5K to 10K. Predicting a marathon from a 5K assumes you've done the long-run training to match, so treat long-distance predictions as a best case.
Getting closer to the prediction
- Build mileage gradually and keep most of it easy.
- Add one quality session a week: intervals or a tempo run.
- Add two strength sessions a week. Research links strength training to better running economy; see strength training for runners.
Train for your next race
Elevus schedules your runs and strength sessions in one week, imports your runs from Apple Watch, and tracks your recovery across both.
Download on theApp StoreFAQ
How accurate are race time predictors?
Usually within a few percent between nearby distances when you have trained for the longer race. They tend to be optimistic for marathons if your weekly mileage is low.
What is the Riegel formula?
A race-time model published by Peter Riegel in 1981: T2 = T1 × (D2 ÷ D1)^1.06, where T1 is a known time over distance D1.
What marathon time does a 25-minute 5K predict?
About 3:59:47, assuming marathon-specific training. A 50-minute 10K predicts about 3:50:01.
References
- Riegel PS. Athletic records and human endurance. American Scientist. 1981;69(3):285–290.