Pace, speed and time
Pace is how long one unit of distance takes, such as minutes per kilometre. Speed is the opposite: distance per hour. Runners usually talk about pace, while treadmills and cyclists often use speed.
Any two of distance, time and pace give you the third. Choose the mode above to solve for pace, finish time or distance, then read the splits and race times that follow.
A worked example
Say you run 10 km in 50 minutes. Your pace is 5:00 per kilometre, which is 12 km/h and about 8:03 per mile. Held steadily, that pace would give exactly 25:00 for 5 km, 1:45:29 for a half marathon and 3:30:59 for a marathon.
Most people cannot hold a 10K pace for a marathon, so treat the longer times as an upper limit on speed rather than a prediction. Training, terrain and conditions all change the result.
Using splits in a race
Splits are the times you should pass each kilometre or mile marker if you run evenly. Watching them helps avoid starting too fast, which is a common mistake. Many runners aim for even or slightly negative splits.
Check the split table against your watch or the race markers, and adjust for hills, which slow uphill sections and speed up downhill ones.
Notes
This is a pacing tool, not a training plan or medical advice. If you are new to running or have a health condition, build up gradually and speak to a professional first.
Questions people ask
How do I calculate running pace?
Divide your total time by the distance. Running 10 km in 50 minutes is 50 ÷ 10 = 5 minutes per kilometre, which is 12 km/h or about 8:03 per mile.
How do I convert pace between km and miles?
One mile is 1.609344 km. Multiply a pace per kilometre by 1.609344 to get the pace per mile, and divide a pace per mile by the same number to get the pace per kilometre. This calculator shows both.
What is a good running pace?
It depends on age, experience and goals, so there is no single answer. A comfortable pace is one you can hold while still able to talk. Improve gradually, and compare with your own past runs rather than with other people.
How accurate are the race times shown?
They simply extend your pace over each distance, assuming you hold it from start to finish. Real races involve fatigue, hills, heat and pacing, so longer distances usually take more time than the straight multiplication suggests.
What are negative splits?
Running the second half of a run faster than the first. The split table shows even splits, which you can use as a starting point for planning your own.