Guide
How to Calculate Running Pace (min/km) and Predict Race Times
Pace is speed turned upside down: instead of how far in an hour, it's how long per kilometer. It's the number runners actually train to, and it takes one division to get.
Pace = time ÷ distance
Run 5 km in 30 minutes: 30 ÷ 5 = 6 minutes per kilometer, written 6:00/km. Run it in 28: 28 ÷ 5 = 5.6 minutes, which is 5 minutes 36 seconds, or 5:36/km.
The part people trip on is the decimal. 5.6 minutes is not 5:60 and not 5:6 — it's 0.6 × 60 = 36 seconds. Always convert the decimal part of a minute by multiplying by 60.
Why runners use pace instead of speed
Speed (km/h) is useful for cars, but it doesn't map to effort over a distance. At 10 km/h a 5 km run takes 30 minutes and a 10 km run takes an hour — you have to multiply to find out how long you'll be out.
Pace answers the question directly: at 6:00/km, each kilometer costs you six minutes. That's why coaching sessions, GPS watches and race pacers are all quoted in min/km or min/mi.
Predicting a race time
Finish time = pace × race distance. At a 6:00/km pace: 10 km = 60 minutes; a half marathon (21.1 km) = 126.6 minutes, about 2:07; a marathon (42.2 km) = 253 minutes, about 4:13.
Treat the longer predictions as optimistic. Pace you can hold for 10 km is normally 10–15% slower over a marathon, so a 4:13 prediction becoming 4:25–4:30 is expected, not a failure.
Using pace to pace a race
Even pacing — running the same min/km throughout — beats starting fast for nearly everyone. A first half run 30 seconds per kilometer quicker than target usually costs more than it gains in the second half.
A practical check: pick a target pace, then look at what it means at the quarter marks. At 5:30/km, 5 km should read about 27:30 and 10 km about 55:00. If you're 45 seconds ahead at 5 km, slow down rather than bank it.
Work it out in one line
Enter the distance in kilometers and the time in minutes into the Running Pace Calculator and it returns your pace in minutes and seconds per kilometer, plus the equivalent speed in km/h.
It's also the quickest way to plan a session: type the distance of your interval and the pace you want to hold, and see the time you should be aiming for.
Try it yourself
Put this guide into practice with our free Running Pace Calculator — no sign-up, no download.
Open the Running Pace Calculator