Running Pace Calculator
Turn a distance and a finish time into a pace per kilometre and per mile, a speed, and what the same pace would give you over a marathon.
Pace
5:00 per km
Pace
8:03 per mile
Speed
12 km/h
Speed
7.4564543 mph
At this pace, a marathon
3:30:59
pace = time ÷ distance · speed = distance ÷ time
Pace is the number runners actually think in, and it is the one a stopwatch does not give you. This turns a distance and a finish time into minutes per kilometre and minutes per mile, the speed those come to, and what the same pace would produce over a marathon — which is the question behind most of the ones people type. The mile is the exact 1.609344 kilometres, and the marathon is the 42.195 kilometres World Athletics standardised in 1921, not a rounded 42.
How it is calculated
pace = time ÷ distance · speed = distance ÷ time
Both are the same division read in opposite directions, which is why a pace of five minutes per kilometre and a speed of twelve kilometres an hour are the same run. The conversion between the two paces is the mile itself: exactly 1.609344 kilometres since the international agreement of 1959.
Source: NIST SP 811 (2008), Appendix B.8 — mile (mi) to kilometer (km) = 1.609 344 E+00
Questions people ask
- Why is a half marathon 21.0975 and not 21.1?
- Because it is exactly half of 42.195. Rounding it to 21.1 adds two and a half metres, which is under a second of running — but there is no reason to introduce an error you can simply not introduce.
- Is the marathon distance really that arbitrary?
- Yes. World Athletics standardised 26 miles 385 yards in 1921, a figure that comes from where the start and finish happened to be placed at the 1908 London Olympics rather than from anything about the distance itself.
- Does an even pace really predict a marathon?
- It predicts the arithmetic, not the race. Holding a 10 km pace for four times the distance is a different physiological problem, and most people slow in the second half. Read the marathon figure as "what this pace would come to", not as a forecast.
- Which mile is this?
- The international mile, exactly 1609.344 metres. The US survey mile differs by about three millimetres in a mile, which no runner will ever notice, but the tools here use the exact factor everywhere rather than switching between them.
Related tools
km/h to mph
Convert kilometers per hour to miles per hour. The ratio is the exact 1.609344 that relates the distance units, because an hour is an hour on both sides.
Miles per Hour to Kilometers per Hour
Convert miles per hour to kilometers per hour in your browser. The factor is the same exact 1.609344 as for distance.
Kilometers to Miles
Convert kilometers to miles instantly in your browser. One mile is exactly 1.609344 kilometers, the factor fixed by the international yard and pound agreement.
Found a problem, or want more?
A number that disagrees with its source is a defect, not a rounding preference.
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