Running pace, finish time and speed
Pace is how long you take per kilometre or per mile, the number runners plan with. Knowing your goal pace tells you whether a target finish time is realistic and what your watch should show at each split. Speed in kilometres or miles per hour is the same information turned around, the way treadmills and cyclists see it.
This calculator works both ways. Enter a finish time to get the pace and speed, or enter a pace to get the finish time, for a kilometre, a mile, 5K, 10K, half marathon or marathon.
How to use it
- Pick the distance.
- Choose what to solve for: pace from time, or time from pace.
- Type the time as h:mm:ss or mm:ss, or the pace as mm:ss per kilometre or per mile.
- Read the pace, finish time and speed in km/h and mi/h.
Example: a 3:30 marathon and a 5:30 pace 10K
Marathon in 3:30:00 10K at 5:30 per km
Pace: 00:04:58 per km, 12.06 km/h Finish time: 00:55:00
A marathon is 42.195 km, so 3 hours 30 minutes means just under five minutes for every kilometre.
Race distances
A marathon is exactly 42.195 km, or 26.2 miles, a length fixed for the 1908 London Olympics and made standard in 1921. A half marathon is 21.0975 km. A 5K is 3.1 miles and a 10K 6.2 miles. One mile is exactly 1.609344 km, so a pace of 5:00 per km equals about 8:03 per mile.
Using pace to plan a race
Most runners race best with even pacing, or a slightly faster second half, called a negative split. Starting faster than goal pace feels easy in the first kilometres and costs dearly at the end. Turn your goal time into a per-kilometre pace here, then check your splits against it during the race.
Real courses are rarely flat or perfectly measured. Hills, wind, heat and weaving around other runners add time, and GPS watches often show a slightly longer distance than the official one. Plan a few seconds per kilometre of margin.
Predicting other distances
Pace slows as distance grows. A common estimate is Peter Riegel's formula: time₂ = time₁ × (distance₂ ÷ distance₁)^1.06. By that rule, a 50-minute 10K predicts a half marathon of about 1 hour 50 minutes. It works best when you have trained for the longer distance.
Questions
How do I enter a time under an hour?
Type minutes and seconds, such as 25:30, or include the hours as 0:25:30.
Can I use it for walking or cycling?
Yes. The maths is the same for any activity; cyclists usually read the speed in km/h or mi/h rather than the pace.
Is anything stored?
No. The numbers are calculated in your browser and not saved.