Predicted Half Marathon Times from 10K Results
| 10K Time | Predicted Half Marathon | Required Pace |
|---|---|---|
| 35:00 | 1:17:09 | 3:39/km |
| 38:00 | 1:23:48 | 3:58/km |
| 40:00 | 1:28:13 | 4:11/km |
| 42:00 | 1:32:39 | 4:23/km |
| 45:00 | 1:39:18 | 4:42/km |
| 48:00 | 1:45:57 | 5:01/km |
| 50:00 | 1:50:22 | 5:13/km |
| 55:00 | 2:01:27 | 5:45/km |
| 60:00 | 2:12:31 | 6:16/km |
Predicted Half Marathon Times from 5K Results
| 5K Time | Predicted Half Marathon | Required Pace |
|---|---|---|
| 18:00 | 1:20:47 | 3:50/km |
| 20:00 | 1:29:44 | 4:15/km |
| 22:00 | 1:38:41 | 4:41/km |
| 25:00 | 1:52:05 | 5:18/km |
| 28:00 | 2:05:29 | 5:56/km |
| 30:00 | 2:14:26 | 6:22/km |
Building Toward a Sub-2 Hour Half Marathon
If your 10K is around 53–54 minutes, the Riegel formula predicts a half marathon of approximately 1:58–1:59. This means sub-2 hours is within reach with proper half marathon-specific training — particularly long runs of 18–20km and weekly tempo runs at 5:30–5:35/km.
Frequently Asked Questions
What half marathon time can I predict from a 45-minute 10K?
A 45-minute 10K (4:30/km) predicts a half marathon of approximately 1:39:18 using the Riegel formula. Your required pace for the half would be around 4:42/km.
Is the half marathon predictor accurate?
For runners with half-marathon specific training (long runs of 16–20km and tempo work), predictions are typically within 2–4%. Less-trained runners may run 5–8% slower than predicted.