Free race time predictor
Predict your race time for every distance
Enter a recent race time and get your predicted finish time and pace for every standard distance, plus a printable pace band.
Show pace in
Advanced: fatigue factor
Less fade (1.00)More fade (1.10)
The standard value is 1.06. Raise it if you fade hard over longer distances, lower it if your endurance is a strength.
| Distance | Predicted time | Pace / mi |
|---|---|---|
| 1500 m | 6:17 | 6:44 |
| 1 mile | 6:46 | 6:46 |
| 3 km | 13:06 | 7:01 |
| 2 mile | 14:06 | 7:03 |
| 5KYour race | 22:30 | 7:15 |
| 8K | 37:02 | 7:27 |
| 10K | 46:55 | 7:33 |
| 15K | 1:12:06 | 7:44 |
| 10 mile | 1:17:41 | 7:46 |
| 20K | 1:37:48 | 7:52 |
| Half marathon | 1:43:30 | 7:54 |
| 25K | 2:03:54 | 7:59 |
| 30K | 2:30:19 | 8:04 |
| Marathon | 3:35:48 | 8:14 |
| 50K | 4:18:20 | 8:19 |
| 50 mile | 7:07:47 | 8:33 |
| 100K | 8:58:37 | 8:40 |
| 100 mile | 14:51:55 | 8:55 |
Looking for a specific jump? See the detailed prediction pages.
Saved races
Saved on this device.
No saved races yet. Enter a result above and save it to compare later.
How it works
- 1
Enter a recent race
Type in a time you ran lately and pick the distance. A fresh, all-out effort gives the best read.
- 2
Read your predictions
See your projected time and pace for every distance from the mile to the marathon, updated as you type.
- 3
Print your pace band
Pick a goal race, choose even or negative splits, then download a pace band to wear on race day.
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Frequently asked questions
- How does the race time predictor work?
- It uses Riegel's formula, T2 = T1 x (D2 / D1)^1.06, to scale one race result up or down to other distances. Enter a recent time and you get a predicted time and pace for everything from the mile to the marathon.
- How accurate is it?
- For distances near your input, predictions are usually within a percent or two. The further you extrapolate, the rougher it gets. Predicting a marathon from a 5K assumes you have the endurance to back up your speed, which is why your long runs matter.
- Which race should I enter?
- Use your most recent all-out effort, and pick a distance close to the one you care about. A recent 10K predicts your half far better than a two-year-old 5K.
- What is a pace band?
- A pace band is a small chart of your target splits that you can print, fold, and wear on your wrist. Ours lists every mile or kilometre split for your goal time, with even or negative-split options.
- Do you store my data?
- No. Every calculation runs in your browser. Saved races stay on your device unless you choose to sign in, and even then they sync only to your own private record.
- Is it free?
- Yes, completely free, no ads in your way, and no account required to use any of the calculators.