Pace Calculator — Running Pace per Mile and per Km

How to use the pace calculator

Choose what you want to find: Pace, Finish time or Distance.
Pick the unit. Miles are selected by default; switch to kilometers if your plan or watch uses them. Pace and custom distances are read in that unit.
For pace or finish time, choose a race: 5K, 10K, half marathon, marathon, or Custom to type your own distance.
Enter the time as hours, minutes and seconds (for pace or distance), or your pace as minutes and seconds per mile or per km (for finish time or distance).
Read the results: pace per km and per mile, finish time, distance and average speed in mph or km/h.

How pace is calculated

Pace is time divided by distance, the inverse of speed:

Pace = time ÷ distance
Finish time = pace × distance
Distance = time ÷ pace
Speed = distance ÷ time in hours

Race distances are the official ones used by World Athletics: 5 km, 10 km, the half marathon (21.0975 km, 13.1094 miles) and the marathon (42.195 km, 26 miles 385 yards). Miles use the exact international definition, 1 mile = 1.609344 km, so 5K is 3.11 miles.

Paces and times are shown rounded to the nearest second, and distances to two decimals, so the marathon appears as 26.22 mi. Calculations use the unrounded values.

Pace examples

5K in 28:00

Your pace is 9:01 per mile (5:36 per km), an average of 6.66 mph.

Marathon at 10:00 per mile

Holding 10:00/mi for 26.2 miles gives a finish time of 4:22:11. That is 6:13 per km and 6.00 mph.

Breaking 2 hours in the half

A 2:00:00 half marathon works out to 9:09 per mile. Because that pace is rounded, give yourself a margin: at an even 9:00/mi you would finish in 1:57:59.

One hour at 9:30 per mile

In Distance mode, 1:00:00 at 9:30/mi takes you 6.32 miles.

Using your pace on race day

The calculator assumes an even pace from start to finish. In practice, hills, wind, heat and crowded starts make some miles slower, so many runners aim to go out controlled and stay even, or run the second half slightly faster.

Expect your GPS watch to show a little more than the race distance. Certified courses are measured along the shortest route a runner could legally take, and World Athletics measurement rules add a short-course prevention factor of 0.1% so a course is never short. You rarely run the perfect tangents, and GPS adds its own error. If your watch says 26.4 miles at the marathon finish, that is normal: pace your race off the mile markers or plan a few seconds per mile faster than your target.

Results only count for USATF records and rankings when the course has been certified, which is why race websites often mention a USATF certification number.

Frequently asked questions

What is a good running pace?

It depends on your age, experience and the distance. A pace you can hold while still speaking in short sentences is a typical easy pace for most training runs; race pace is faster and gets slower as the distance grows.

How do I convert pace per km to pace per mile?

Multiply the pace per km by 1.609344. For example, 5:30 per km becomes 8:51 per mile. The calculator always shows both, whichever unit you choose.

What pace do I need for a 4-hour marathon?

About 9:09 per mile (5:41 per km), or 6.55 mph. Since paces are rounded to the second, aim slightly faster to leave room for water stops and the extra distance your watch will record.

How long is a half marathon in miles?

13.1094 miles, exactly half of the 42.195 km marathon (21.0975 km). Most people round it to 13.1.

What is the difference between pace and speed?

Pace is time per distance, such as 9:00 per mile. Speed is distance per time, such as 6.67 mph. Runners usually think in pace; treadmills often display speed, so the calculator shows both.

Why can't I enter a time of zero?

Pace and distance both divide by time, and distance divides by pace, so zero would be meaningless. Enter at least one second.

Sources

Results are estimates based on an even pace and the distance you enter. Real race times depend on course, weather and how you feel on the day.