10K to Marathon Conversion Calculator
Moving from 10K to Marathon is a natural progression for road racers. This tool predicts your Marathon finish time from your 10K result, accounting for glycogen management, fatigue accumulation, and the pacing differences between these distances.
Quick answer: a 42:00 10K converts to about 3:31:47 for the marathon (typical range 3:21:08 to 3:47:07).
10K to Marathon conversion table
Estimates only – individual results vary with training, conditions and event experience.
| 10K time | Predicted Marathon | Range |
|---|---|---|
| 29:00 | 2:26:14 | 2:18:53–2:36:49 |
| 30:30 | 2:33:48 | 2:26:03–2:44:55 |
| 32:00 | 2:41:22 | 2:33:14–2:53:02 |
| 33:30 | 2:48:55 | 2:40:25–3:01:09 |
| 35:00 | 2:56:29 | 2:47:36–3:09:15 |
| 36:30 | 3:04:03 | 2:54:47–3:17:22 |
| 38:00 | 3:11:37 | 3:01:58–3:25:29 |
| 39:30 | 3:19:11 | 3:09:09–3:33:35 |
| 41:00 | 3:26:45 | 3:16:20–3:41:42 |
| 42:30 | 3:34:18 | 3:23:31–3:49:49 |
| 44:00 | 3:41:52 | 3:30:42–3:57:55 |
| 45:30 | 3:49:26 | 3:37:53–4:06:02 |
| 47:00 | 3:57:00 | 3:45:04–4:14:09 |
| 48:30 | 4:04:34 | 3:52:15–4:22:15 |
| 50:00 | 4:12:08 | 3:59:26–4:30:22 |
| 51:30 | 4:19:41 | 4:06:37–4:38:29 |
| 53:00 | 4:27:15 | 4:13:48–4:46:35 |
| 54:30 | 4:34:49 | 4:20:59–4:54:42 |
| 56:00 | 4:42:23 | 4:28:10–5:02:49 |
| 57:30 | 4:49:57 | 4:35:21–5:10:55 |
| 59:00 | 4:57:31 | 4:42:32–5:19:02 |
| 1:00:30 | 5:05:04 | 4:49:43–5:27:09 |
How it works
The 10K→Marathon conversion blends Riegel's power-law scaling with VDOT oxygen-cost validation. With a 4x distance jump, the predictor applies additional correction factors for the major physiological shift between these events. Where both distances fall within aerobic range, critical speed modeling adds a third reference point. The result is a predicted time with a confidence range.
Training advice
Use a recent race or time-trial 10K for the best prediction. To reach your Marathon target, build high mileage and fueling strategy progressively. Marathon demands specific preparation — your 10K fitness provides the foundation, but high mileage and fueling strategy closes the gap.
Frequently asked questions
How accurate is a 10K to Marathon prediction?
With a recent all-out 10K time, predictions are typically within 4-8% of actual Marathon performance. Accuracy improves when the 10K effort is from the past 6-8 weeks under normal conditions.
What training should I do to reach my predicted Marathon time?
Focus on high mileage and fueling strategy. Your 10K fitness provides the speed foundation — building aerobic at 75-85% VO2max capacity through progressive training is the key to hitting the target.
Can I use an old 10K time for this prediction?
Recent times (within 6-8 weeks) give the most reliable predictions. Older results may not reflect your current fitness, especially if your training has changed significantly.