Riegel
Pete Riegel noticed in 1977 that race times grow a little faster than distance. Double the distance and your time grows about 2.1 times, not 2. It’s simple and holds up well from 5K to marathon.
Free tool
Race time predictor
Your race time predictor: enter one recent race and Anew estimates what you could run at 5K, 10K, half marathon and marathon. A 25:00 5K, for example, points to about 52:00 for 10K, 1:55 for a half and 3:59 for a marathon, if you train for that distance.
Free race predictor
What could you run?
Enter a recent race. You’ll see what that fitness means at the other distances.
- 10K
- 52:00
- Half marathon
- 1:55:02
- Marathon
- 3:58:51
Your VDOT 38.3
Midpoint of the Riegel and Daniels models, with both shown as the range. It assumes you train for the longer race.
Want to get there? Luis builds the plan around your life. 
Equivalent race times from your 5K
Each row is the same fitness at different distances, using the midpoint of both models.
| 5K | 10K | Half | Marathon | VDOT |
|---|---|---|---|---|
| 18:00 | 37:26 | 1:22:41 | 2:52:32 | 56.3 |
| 20:00 | 41:35 | 1:31:55 | 3:11:33 | 49.8 |
| 22:00 | 45:45 | 1:41:10 | 3:30:31 | 44.5 |
| 24:00 | 49:55 | 1:50:25 | 3:49:25 | 40.2 |
| 26:00 | 54:06 | 1:59:39 | 4:08:15 | 36.6 |
| 28:00 | 58:17 | 2:08:53 | 4:27:01 | 33.5 |
| 30:00 | 1:02:28 | 2:18:05 | 4:45:42 | 30.8 |
| 32:00 | 1:06:39 | 2:27:16 | 5:04:18 | 28.5 |
| 34:00 | 1:10:50 | 2:36:25 | 5:22:51 | 26.5 |
| 36:00 | 1:15:01 | 2:45:33 | 5:41:20 | 24.7 |
| 38:00 | 1:19:12 | 2:54:39 | 5:59:44 | 23.1 |
| 40:00 | 1:23:23 | 3:03:44 | 6:18:06 | 21.7 |
How the prediction works
Daniels VDOT
Jack Daniels and Jimmy Gilbert estimated how much oxygen a pace costs and how much of your maximum you can hold for a given time. Your race gives a VDOT; the prediction is the time that gives the same VDOT at another distance.
What it doesn’t know
Your week, your sleep, the heat, the hills or your legs on race day. A prediction is a starting point. Luis takes it from there and adjusts as you train.
Questions runners ask
- How accurate is a race time predictor?
- Usually within a few minutes for a half marathon if you train for it. For the marathon it tends to be optimistic unless your long runs and weekly volume are there.
- What marathon time does a 25-minute 5K predict?
- About 3:58 to 4:00. The half marathon lands near 1:55 and the 10K near 52 minutes.
- What is VDOT?
- A number from Jack Daniels that sums up your current running fitness from a race result. The higher it is, the faster your paces at every distance.
- Should I use my best time ever or a recent one?
- A recent one, ideally from the last six to eight weeks and run all out. An old best tells you who you were, not who you are today.
- Can Anew build a plan for the predicted time?
- Yes. Tell Luis your race and why you’re running it, and he builds a plan around your life that starts where you are today.
From a number to a plan.
Luis turns your goal into weeks you can actually live with.