Pace calculator
Enter a distance and a time to see your pace per mile and per kilometer, your speed, and what that pace gives over a 5K, a 10K, a half marathon and a marathon. A second tool turns a pace into a finish time.
Pace from distance and time
This answer is for the example values in the boxes above. 5 miles in 40:00. Change the boxes to see your own answer.
A mile is 1.609344 kilometers. Paces and times are rounded to the second.
The times of the races are for holding this pace over the whole distance.
Finish time from distance and pace
The finish time is the distance times the pace, rounded to the second.
How it works
Pace is the time that one unit of distance takes. The first panel divides your time by your distance to get the pace per kilometer, multiplies it by 1.609344 to get the pace per mile, and turns both into speeds. It then multiplies the pace per kilometer by the length of four common races to give the finish time at that pace.
The second panel goes the other way: a distance and a pace per mile or per kilometer give the finish time. Times and paces are rounded to the second.
A worked example
A runner covers 5 miles in 40 minutes. The pace is 8:00 a mile and 4:58 a kilometer, and the speed is 7.50 miles an hour, or 12.07 kilometers an hour. At that pace a 5K takes 24:51, a 10K 49:43, a half marathon 1:44:53 and a marathon 3:29:45.
In the second panel, 10 kilometers at 5:00 a kilometer take 50:00. That pace is 8:03 a mile, which is a speed of 7.46 miles an hour or 12.00 kilometers an hour.
The distances
A mile is 1.609344 kilometers. A 5K is 5 kilometers and a 10K is 10. The marathon is 42.195 kilometers and the half marathon is half of it, 21.0975 kilometers.
What it leaves out
The finish times assume one steady pace over the whole distance, which few races are: hills, heat and tiredness change it. The result is arithmetic, not a prediction of what you can run, and it gives no training advice.
Sources
Questions
How do you calculate running pace?
Divide the time by the distance. Five miles in 40 minutes is 8 minutes a mile, which is 4:58 a kilometer. Speed is the distance divided by the time, so that run is 7.5 miles an hour.
What is the difference between pace and speed?
Pace is the time for a distance, such as minutes a mile, and speed is the distance for a time, such as miles an hour. A smaller pace number is faster: 8:00 a mile is 7.5 miles an hour, and 9:00 a mile is 6.7.
What pace is a four-hour marathon?
A marathon is 42.195 kilometers, so a time of four hours means about 5:41 a kilometer, which is 9:09 a mile.
How many kilometers are in a mile?
A mile is 1.609344 kilometers exactly, as the National Institute of Standards and Technology lists it. An 8:00 mile is 4:58 a kilometer.
How long is a half marathon?
A half marathon is 21.0975 kilometers, which is half of a marathon and about 13.1 miles. The marathon is 42.195 kilometers, about 26.2 miles, and World Athletics lists it among the distances of its road world records.
Do the finish times assume an even pace?
Yes. Each time is the distance multiplied by your pace, so it holds that pace from the first step to the last. Hills, heat and a late fade change a real race, so read the times as arithmetic and not as a forecast.
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