Run Pace Race Time Predictor
A recent race is the most honest measure of your fitness. Enter its distance and finish time, and the predictor estimates what that same fitness is worth over 5K, 10K, 10 miles, the half marathon and the marathon, with the pace per kilometre and per mile for each.
Use it to set a realistic goal before you commit to a training block, or to check whether a target time for your next race matches what you have already run.
Predict your race times
| Distance | Predicted time | Pace (min/km) | Pace (min/mile) |
|---|---|---|---|
| 5K | 23:59 | 4:48 | 7:43 |
| 10K(your race) | 50:00 | 5:00 | 8:03 |
| 10 Miles | 1:22:48 | 5:09 | 8:17 |
| Half Marathon | 1:50:19 | 5:14 | 8:25 |
| Marathon | 3:50:01 | 5:27 | 8:46 |
Predictions use the Riegel formula (T2 = T1 × (D2 / D1)1.06). It works best between similar distances: a 10K predicts a half marathon well, but a 5K is a rough guide to a marathon, which also depends on endurance training.
Frequently asked questions
How does the race time predictor work?
It uses the Riegel formula, T2 = T1 × (D2 / D1)^1.06. The exponent of 1.06 accounts for the way pace slows as races get longer, so doubling the distance takes a little more than twice the time.
How accurate are race time predictions?
Predictions are most reliable between similar distances, such as a 10K result predicting a half marathon. Predicting a marathon from a 5K assumes you have the endurance to match your speed, which most runners only have after consistent long runs.
What 10K time does a 20-minute 5K predict?
A 20:00 5K predicts about 41:42 for 10K, 1:32 for the half marathon and 3:12 for the marathon, if you train properly for each distance.
Which race result should I enter?
Use a recent, all-out race on a reasonably flat course in good conditions. A training run or a race in heat or on hills will underestimate what you can do.