A recent race in. Your marathon out.
Type any recent race result. We use the Riegel formula to project your marathon finish — the most-asked race-time prediction question.
From 10K in 50:00, here are your projected race times.
Find Marathon races →Reference table for popular shorter-race times and the Riegel-projected marathon. Riegel is most reliable when the input distance is within ~3× the marathon — a half marathon predicts your marathon time more accurately than a 5K.
| Input race result | Predicted | Notes |
|---|---|---|
| Half marathon 1:30:00 | Marathon ~3:09 | Strong sub-3:10 territory. |
| Half marathon 1:45:00 | Marathon ~3:41 | Solid sub-3:45 base. |
| Half marathon 2:00:00 | Marathon ~4:13 | Comfortable sub-4:15 prediction. |
| 10K 40:00 | Marathon ~3:11 | Sub-3:15 marathon territory. |
| 10K 50:00 | Marathon ~3:59 | Sub-4-hour goal. |