Race Time Predictor
Enter one recent race result and we'll predict your equivalent time at other standard distances, using Riegel's formula (T2 = T1 × (D2/D1)^1.06).
| Distance | Predicted time | Pace /km |
|---|---|---|
| 1 Mile | 7:31 | 4:40 |
| 5K | 25:00 | 5:00 |
| 10K | 52:07 | 5:13 |
| 15K | 1:20:07 | 5:20 |
| 10 Mile | 1:26:19 | 5:22 |
| Half Marathon | 1:55:00 | 5:27 |
| Marathon | 3:59:47 | 5:41 |
This estimate uses a generic formula. Connect your Strava/Whoop/Garmin data for a version personalised to your actual training.
Get early accessWhat a race time prediction is
A race time prediction takes one result you have already run and estimates your equivalent finish time at a different distance. It answers a common question: given a recent 10K, what marathon time is realistic right now.
How it is calculated
This calculator uses Riegel's formula: T2 = T1 × (D2/D1)^1.06. T1 and D1 are the time and distance of your known result, D2 is the target distance, and T2 is the predicted time. The 1.06 exponent accounts for the fact that pace slows as distance increases, so the prediction is not a simple linear scaling of pace. Predictions are generated for seven standard distances: 1 mile, 5K, 10K, 15K, 10 mile, half marathon, and marathon.
Why runners use it
It gives a grounded starting point for a goal time at a distance you have not raced recently, or at all, based on fitness you have already demonstrated at another distance.