Running Pace Explained: Per Km, Per Mile and Speed
Runners talk in pace, such as 5:30 per kilometre. Treadmills, cyclists and car dashboards talk in speed, such as 10.9 km/h. The two describe the same effort from opposite directions, and switching between them is a small calculation that goes wrong in a few predictable ways.
This article shows how to calculate pace from a finish time, how to convert between kilometres and miles, how to read a treadmill display, and how to turn a pace into a finish time for the usual race distances.
Calculating pace from distance and time
Pace is how long one unit of distance takes. Convert the total time to seconds, divide by the distance, then convert back to minutes and seconds.
pace = total time ÷ distanceSpeed is the reverse: distance ÷ time.
Worked example: a 5 km run in 27:30. That is 27 × 60 + 30 = 1,650 seconds. Divided by 5 km gives 330 seconds per kilometre, which is 5:30 per km. In speed terms, 5 km in 27.5 minutes is 5 ÷ (27.5 ÷ 60) = 10.91 km/h.
Converting between kilometres and miles
One mile is 1.609344 kilometres, so a pace per mile is the pace per kilometre multiplied by 1.609344. For the example above, 330 × 1.609344 = 531 seconds, or 8:51 per mile. To go the other way, divide by 1.609344.
| Per km | Per mile | km/h | mph |
|---|---|---|---|
| 4:00 | 6:26 | 15.00 | 9.32 |
| 5:00 | 8:03 | 12.00 | 7.46 |
| 5:30 | 8:51 | 10.91 | 6.78 |
| 6:00 | 9:39 | 10.00 | 6.21 |
| 6:30 | 10:28 | 9.23 | 5.74 |
| 7:00 | 11:16 | 8.57 | 5.33 |
| 8:00 | 12:52 | 7.50 | 4.66 |
A quick mental check: a pace per mile is always about 60% larger as a number than the matching pace per kilometre, because a mile is about 1.6 km.
Reading a treadmill display
Most treadmills show speed, not pace. Because pace and speed are reciprocals, you can convert with 60 as the constant:
pace (min per km) = 60 ÷ speed (km/h)Use mph instead of km/h to get minutes per mile.
At 10 km/h the pace is 60 ÷ 10 = 6 minutes per km, and at 12 km/h it is exactly 5:00. At 6 mph the pace is 10:00 per mile.
The decimal-minutes trap: 60 ÷ 11 = 5.4545 minutes does not mean 5:45. The 0.4545 is a fraction of a minute, so multiply it by 60 to get about 27 seconds. The pace at 11 km/h is 5:27 per km.
From pace to finish time
Multiply your pace by the distance to get a finish time. At a steady 5:30 per km (330 seconds):
| Race | Distance (km) | Finish time |
|---|---|---|
| 5K | 5 | 27:30 |
| 10K | 10 | 55:00 |
| Half marathon | 21.0975 | 1:56:02 |
| Marathon | 42.195 | 3:52:04 |
Working backwards works the same way. A half marathon in 1:45:00 is 6,300 seconds over 21.0975 km, so you need about 298.6 seconds per km, or roughly 4:59 per km.
Rounding is worth a thought at longer distances. A marathon pace of 5:41.3 per km rounded down to 5:41 looks harmless, but 0.27 seconds per km over 42.195 km adds up to about 11 seconds by the finish. Keep the unrounded pace in your calculation and round only the final time.
Averaging pace correctly
Averaging several splits is another place where pace and speed behave differently. Suppose you run the first 5 km at 5:00 per km and the second 5 km at 6:00 per km. Both halves cover the same distance, so the average pace is simply the midpoint, 5:30 per km, and the check is easy: 25:00 plus 30:00 is 55:00 for 10 km.
Averaging the speeds gives a different, wrong answer. The speeds are 12 and 10 km/h, whose simple average is 11 km/h, but 10 km in 55 minutes is 10 ÷ (55 ÷ 60) = 10.91 km/h. An 11 km/h average would imply 5:27 per km. The reason is that you spend more time at the slower speed. When the distances are equal, average the paces; when the times are equal, average the speeds; otherwise, divide total distance by total time.
Common pace mistakes
- Mixing units. A marathon is 42.195 km, which is 26.2 miles. Dividing a kilometre distance by a mile pace (or the reverse) gives a wrong time that looks plausible.
- Treating 5.5 as 5:50. Half a minute is 30 seconds, so 5.5 minutes is 5:30.
- Trusting watch distance exactly. GPS can read a little long or short, and the race course is measured along the shortest legal line, so your watch pace and the official pace may differ.
- Ignoring terrain. Hills, wind and heat slow you down for the same effort, so a flat pace target is not always the right goal for every kilometre.
To skip the arithmetic, the pace calculator solves for pace, time or distance, the speed, distance and time calculator covers any one of the three, and the kilometers to miles converter handles distances.
- Pace Calculator: Choose what you want to find, fill in the other two values and read the answer. Pace comes out per mile and per kilometre, and speed in two units.
- Kilometers to Miles Converter: Enter a distance in kilometers and get statute miles, rounded to six decimal places. One kilometer is 0.621371 miles, and one mile is exactly 1.609344 kilometers.
- Speed, Distance & Time Calculator: Choose whether you want the speed, the distance or the time, fill in the other two values and press Calculate. The guide below covers the three formulas, unit handling and worked examples.
This article is general information, not professional advice. See our Disclaimer and Editorial Policy.
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