Two units for the same speed
The treadmill says 11 km/h, the training plan says 5:30 min/km. Both describe how fast you run, just from two angles. Speed in km/h tells you how many kilometres you cover in an hour. Pace in min/km tells you how long you need for one kilometre. The higher the km/h, the lower the pace.
In everyday training you constantly switch between the two: on the treadmill at the gym, with training plans from books or with figures in miles from the US or UK. This article shows the formulas, a lookup table and the typical mistakes.
The formulas
1. Pace in minutes = 60 ÷ km/h. At 12 km/h: 60 ÷ 12 = 5, so 5:00 min/km.
2. km/h = 60 ÷ pace in minutes. At 6:00 min/km: 60 ÷ 6 = 10 km/h.
The tricky part is converting between decimal minutes and minutes:seconds. If you calculate 60 ÷ 11 km/h, you get 5.4545 minutes. The decimals are not seconds: 0.4545 minutes × 60 = 27 seconds. So the pace is 5:27 min/km, not 5:45.
The same applies the other way round: 5:30 min/km is 5.5 minutes, not 5.3. Calculated correctly, 60 ÷ 5.5 = 10.9 km/h. If you calculate 60 ÷ 5.3, you get 11.3 km/h and run too fast on the treadmill.
Treadmill conversion table
| km/h | min/km | min/mile | mph |
|---|---|---|---|
| 7 | 8:34 | 13:48 | 4.3 |
| 8 | 7:30 | 12:04 | 5.0 |
| 9 | 6:40 | 10:44 | 5.6 |
| 10 | 6:00 | 9:39 | 6.2 |
| 11 | 5:27 | 8:47 | 6.8 |
| 12 | 5:00 | 8:03 | 7.5 |
| 13 | 4:37 | 7:26 | 8.1 |
| 14 | 4:17 | 6:54 | 8.7 |
| 15 | 4:00 | 6:26 | 9.3 |
| 16 | 3:45 | 6:02 | 9.9 |
For values in between, use the pace calculator: choose the “Time” or “Distance” mode and you can enter the speed directly in km/h and see the pace in min/km and min/mile.
Miles and kilometres
One mile is exactly 1.609344 km. To convert a kilometre pace into a mile pace, multiply by 1.609344. 5:00 min/km (300 seconds) becomes about 483 seconds, or 8:03 min/mile. To go the other way, divide by 1.609344. For speed: mph = km/h ÷ 1.609344, so 12 km/h equals 7.5 mph.
Why the treadmill feels different
Many runners notice that the same pace feels easier or harder on the treadmill than outdoors. There are several reasons: there is no air resistance, the belt pulls your foot along a little, and not every machine's display is accurately calibrated. A common rule of thumb is to set an incline of about 1% to make up for the missing air resistance. Whether that suits you is best judged by how you feel and how you breathe.
Common mistakes at a glance
1. Reading decimal minutes as seconds: 5.5 minutes is 5:30, not 5:50.
2. Dividing the wrong way round: km/h ÷ 60 does not give a meaningful value. It is always 60 divided by the other value.
3. Mixing miles and kilometres: a mile pace of 8:00 is much faster than a kilometre pace of 8:00.
How to work out your finish time from pace and distance is explained in the guide How to Calculate Your Running Pace.