PR Pacer · Tools
Marathon Pace Calculator
Enter one recent race result. Get predicted times for every common distance, plus training paces.
| Distance | Predicted time | Pace |
|---|
Suggested training paces
| Session type | Pace range |
|---|
Estimates only, based on the Riegel formula and common coaching guidelines. Not a guarantee — actual results depend on training, pacing, course, and weather.
How this works
This calculator uses the Riegel formula, one of the most widely used race-time prediction models: predicted time equals your known time multiplied by the ratio of the two distances raised to the power of 1.06. It's a reasonable starting estimate — most accurate between distances that aren't too far apart (a recent 10K predicts a half marathon better than it predicts a marathon), since it assumes your training and conditioning transfer similarly across distances.
Turn this estimate into an actual training plan.
Free to start.
Frequently asked
- How does a race time predictor work?
- This one uses the Riegel formula: predicted time = known time × (predicted distance / known distance)^1.06 — a widely used endurance-prediction model.
- How accurate are these predictions?
- A reasonable starting estimate, not a guarantee. Accuracy drops the further apart the two distances are, and real results depend on distance-specific training, pacing, course, and weather.
- What training paces should I use?
- General ranges based on common coaching guidelines relative to your current 5K-equivalent fitness — a starting point, not a precise prescription.