Slobiq Health / Training and fitness / Running pace calculator
Running pace calculator
Enter a distance and either your finishing time or your pace to see the pace, speed and predicted times for common races.
These are general estimates, not medical advice, and they do not replace a doctor, dietitian or trainer. If you are pregnant, under 18, have a health condition or take medication, talk to a professional before changing your diet or training.
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About this tool: Running pace calculator
Pace is the time it takes to cover one kilometre or one mile, and speed is the distance per hour. Runners use pace to plan races and training. Enter a distance and your time, or the pace you hold, and the calculator gives the other.
The predictions use the Riegel formula (1981): the time grows a little faster than the distance. It works best when you predict a distance not more than about four times longer than the one you ran, and when you have trained for the longer one. A marathon prediction from a 5 km time is usually too optimistic.
Formula
Pace = time ÷ distance. Speed = distance ÷ time in hours. Predicted time T2 = T1 × (D2 ÷ D1)^1.06, where T1 is your time over distance D1.
Worked example
10 km in 50:00 gives a pace of 5:00 per km and a speed of 12 km/h. The predictions are about 23:59 for 5 km, 1:50:19 for a half marathon and 3:50:01 for a marathon.
Sources and accuracy
- Formulas and sources last reviewed
- Accuracy
- An estimate from published formulas. Real needs differ between people, so treat it as a starting point and adjust to how your body responds.
This tool uses a standard method named in the text above.
Frequently asked questions
Is the marathon prediction reliable?
Treat it as an upper limit of what is possible with good training. Long distances need endurance that a 10K does not show.
How do I convert km pace to miles?
Choose miles in the units box and enter the pace or time. One mile is 1.609 km, so a 5:00 per km pace is about 8:03 per mile.
What if I stop or walk during the run?
Use the total time including stops for a realistic pace, or only the moving time for your running pace.