Running pace calculator

Runners talk about pace rather than speed: how many minutes and seconds one kilometre takes them. A pace of 5:30 means that each kilometre takes 5 minutes and 30 seconds. Your watch shows it straight away, but the treadmill at the gym wants speed in km/h, and you want to know whether you can break an hour for 10 km.

From speed to pace

On the treadmill you set the speed and want to know which pace that corresponds to.

How it works

Pace is the reciprocal of speed. An hour has 3,600 seconds, so if a kilometre takes p seconds, you are running at

$$v=\frac{3600}{p}\text{km/h}$$

and a route of d kilometres takes d · p seconds.

A pace of 5:30 is 5 · 60 + 30 = 330 seconds per kilometre, so the speed is

$$v=\frac{3600}{330}\approx 10.91\text{km/h}$$

Five kilometres takes 5 · 330 = 1650 seconds, which is 27 minutes and 30 seconds, and 10 km takes exactly 55 minutes. The half marathon is 21.0975 km long:

$$21.0975\cdot 330\approx 6962\text{s}$$

For whole hours, $6962÷3600$ gives 1, with 3,362 seconds left over. From the remainder we take whole minutes: $3362÷60$ is 56, with 2 seconds left over. So the half marathon takes 1 h 56 min 2 s, and the marathon, twice as long, takes 3 h 52 min 4 s.

The times calculated here hold only if you keep the pace for the whole route. Few people manage that over a marathon, so treat the calculated time as a target rather than a certainty.

Going from speed to pace works the other way round. A kilometre takes $3600÷v$ seconds, so at 12 km/h it takes $3600÷12=300$ seconds, or 5 minutes per kilometre.

If you are working out a car journey rather than a run, use the speed, time and distance calculator.