How this calculator works
Average speed is distance divided by elapsed time. The page converts every length to metres, every time to seconds and every speed to metres per second before dividing, so kilometres with minutes or miles with hours work without manual conversion. The distance and time modes rearrange the same relationship. The speed returned is an average over the whole interval, not necessarily the speed at any one instant: a trip that includes stops can have a high cruising speed and a much lower average.
Formula
speed = distance / time. distance = speed x time. time = distance / speed. A kilometre is 1,000 m, an hour is 3,600 s and 1 km/h is 1/3.6 m/s.
Worked example
Covering 150 km in 2 hours gives an average speed of 75 km/h. At 60 km/h for 1.5 hours the distance is 90 km. A speed of 60 mph is 96.56 km/h or 26.82 m/s.
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Frequently asked questions
Is this average speed or instantaneous speed?
It is average speed over the entered distance and time. If you want instantaneous speed, you need a measurement over a very short interval or a speed sensor reading.
Why is my average lower than my cruising speed?
Stops, traffic lights, slow towns and acceleration all take time without adding distance at the cruising rate. Average speed reflects the whole interval, including those delays.
Can I use nautical miles and knots?
The speed selector does not include knots, so enter a speed in km/h, mph or m/s. Convert knots with 1 kn = 1.852 km/h, or use the nautical mile calculator, which works directly in knots.
Does a change of direction matter?
This is speed, not velocity, so direction is ignored. A car returning to its start still has a positive average speed, while its average velocity would be zero.