How it works
Pace is time divided by distance. If you run 10 kilometers in 50 minutes, each kilometer took 5 minutes on average, so your pace is 5:00 per kilometer.
The calculator uses that one relationship three ways:
- Pace is time divided by distance.
- Finish time is pace multiplied by distance.
- Distance is time divided by pace.
Speed carries the same information the other way round: distance per hour instead of time per kilometer or mile. A pace of 5:00 per kilometer is 12 km/h.
Switching between kilometers and miles converts the numbers already in the form, using the exact international definition of 1 mile = 1.609344 km.
The formula
pace = time ÷ distance
time = pace × distance
distance = time ÷ pace
speed = 60 ÷ pace (in minutes per km or mile)Worked example
You finish a 10K in 50:00.
- The time is 50 minutes.
- Divide by the distance: 50 ÷ 10 = 5 minutes per kilometer, written 5:00 /km.
- For pace per mile, multiply by 1.609344: 5 × 1.609344 = 8.047 minutes, which is 8:03 per mile.
- Speed is 60 ÷ 5 = 12 km/h, or 7.5 mph.
Questions
How do I convert pace per kilometer to pace per mile?
Multiply the pace in minutes by 1.609344. To go from miles to kilometers, divide by 1.609344. For example, 5:00 per km is 8:03 per mile, and 8:00 per mile is 4:58 per km. Switching the unit in the calculator does this for you.
How long are a half marathon and a marathon?
A marathon is 42.195 km (26.2 miles) and a half marathon is 21.0975 km (13.1 miles). The distance buttons fill these in exactly, in whichever unit you have selected.
Why does my GPS watch show a quicker pace than my race result?
Race courses are measured along the shortest possible route. Most runners cover a little more than that by drifting wide on bends and weaving past others, and GPS tracks also wander near tall buildings and trees. The watch usually records a longer distance than the course, so it shows a slightly quicker pace than the official result.
What is the difference between pace and speed?
Pace is time per distance, such as minutes per kilometer. Speed is distance per time, such as km/h or mph. Runners mostly talk in pace, while treadmills usually show speed. The treadmill pace converter switches between the two.
Does the calculator round my numbers?
Paces and times are shown to the nearest second. The math runs on the unrounded values, so a finish time worked out from a pace can differ from mental arithmetic by a second.