Speed, distance and time calculator
Choose what you want to find, enter the other two values and pick your units. You also get the speed converted into metres per second, km/h and mph.
How this calculator works
Speed, distance and time are tied together by one idea: speed is how much distance you cover in each unit of time. If you know any two, rearranging gives the third. This calculator keeps your chosen units throughout, so 150 kilometres in 2 hours comes out as 75 kilometres per hour, and then it converts that speed into the other common units for comparison.
Remember that this gives average speed. A car that sits in traffic and then speeds up will have varied its speed all along, but the journey total still gives one honest average.
The formula behind it
- speed = distance ÷ time
- distance = speed × time
- time = distance ÷ speed
The "speed, distance, time" triangle is just a memory aid for these three lines.
A worked example
A marathon is 42.195 km. How long does it take at a steady 12 km/h? Time = 42.195 ÷ 12 = 3.5163 hours, which is 3 h 30 m 59 s.
Questions people ask
How do I convert minutes into hours?
Divide by 60. 45 minutes is 0.75 hours. Or just choose minutes as the time unit and the calculator handles it.
Is this average or instantaneous speed?
Average. It uses the total distance and total time, so it smooths out any stops or bursts of speed on the way.
How do I turn km/h into m/s?
Divide by 3.6. So 72 km/h is 20 m/s. To go the other way, multiply by 3.6.
What if my units are mixed, like metres and hours?
Convert one of them first, or pick the pair that matches your data. The result is always in distance unit per time unit.