Pace is time divided by distance. A 5K in 28:30 is a pace of 5:42 per kilometer, or 9:10 per mile. Enter the distance in kilometers or miles and your time as mm:ss or h:mm:ss; the calculator gives your pace both ways, your average speed and predicted times for the classic race distances.
Pace chart
| Per km | Per mile | Speed | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|---|---|
| 4:00 | 6:26 | 15.0 km/h | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 4:30 | 7:15 | 13.3 km/h | 22:30 | 45:00 | 1:34:56 | 3:09:53 |
| 5:00 | 8:03 | 12.0 km/h | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 5:30 | 8:51 | 10.9 km/h | 27:30 | 55:00 | 1:56:02 | 3:52:04 |
| 6:00 | 9:39 | 10.0 km/h | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 6:30 | 10:28 | 9.2 km/h | 32:30 | 1:05:00 | 2:17:08 | 4:34:16 |
| 7:00 | 11:16 | 8.6 km/h | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
| 8:00 | 12:52 | 7.5 km/h | 40:00 | 1:20:00 | 2:48:47 | 5:37:34 |
The times in this table assume the same pace for the whole race. In practice you slow down over longer distances, which is what the predictions below account for.
Predicting your race times
Riegel’s formula, published in 1981, estimates how much you slow down as the distance grows: T2 = T1 × (D2 ÷ D1)^1.06. From a 5K in 25:00:
| Race | Predicted time |
|---|---|
| 10K | 52:07 |
| Half marathon | 1:55:00 |
| Marathon | 3:59:47 |
The exponent 1.06 means that doubling the distance takes a little more than twice as long. The prediction is best for distances close to the one you ran, and for races you have trained for: if your longest run is 15 km, the marathon figure is optimistic.
Typing your time
- 28:30 means 28 minutes 30 seconds.
- 1:52:00 means 1 hour 52 minutes.
- 28 means 28 minutes, and 28.5 means 28 and a half minutes (28:30).
Pace or speed?
Runners think in pace (minutes per kilometer or mile); treadmills and cyclists think in speed (km/h or mph). To convert, divide 60 by the pace in minutes: a 6:00 pace is 60 ÷ 6 = 10 km/h. The calculator shows both, so you can set a treadmill to match your outdoor runs.
All calculations happen on your phone, so the calculator works on a run with no signal too.
Frequently asked questions
How do I calculate my running pace?
Divide your time by the distance. A 5K in 28:30 is 1,710 seconds ÷ 5 = 342 seconds per kilometer, or 5:42 per km. Per mile it is 9:10.
How do I convert pace per km to pace per mile?
Multiply the pace per kilometer by 1.609. A 5:00 per km pace is 8:03 per mile; a 9:00 per mile pace is 5:36 per km.
How accurate are the race predictions?
They use Riegel's formula (Peter Riegel, American Scientist, 1981), which works well for races you have trained for. For a first marathon, most runners finish slower than the prediction, because endurance has not caught up with speed.
Can I use it for walking or cycling?
Yes. Enter any distance and time and you get the pace and the average speed. The race predictions are meant for running.
Last checked: