Find speed, distance or time. This free speed calculator solves any one from the other two, in your choice of units, and shows the result in km/h, mph and m/s.
Enter any two
Fill in any two of distance, time and speed, and the calculator works out the third using speed = distance ÷ time. Leave the value you want to find blank.
Speed
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Enter any two values
Works for any constant (average) speed — running, driving, cycling, walking and more. The result is shown in km/h, mph and m/s for convenience.
Use this free speed calculator to find speed, distance or time. Enter any two of them — in your choice of units — and the calculator works out the third using speed = distance ÷ time.
What this speed calculator does
A speed calculator solves the relationship between speed, distance and time. Enter any two and it finds the missing one, then shows the result in km/h, mph and m/s (or in km, miles and metres, or hours, minutes and seconds).
The speed, distance and time formulas
Speed = distance ÷ time
Distance = speed × time
Time = distance ÷ speed
For example, covering 100 km in 2 hours gives a speed of 50 km/h (about 31 mph or 13.9 m/s).
Common speed conversions
From
To
Multiply by
km/h
m/s
÷ 3.6
km/h
mph
× 0.6214
mph
km/h
× 1.609
m/s
km/h
× 3.6
How to use the speed calculator
Enter any two of distance, time and speed.
Pick the units for each from the dropdowns.
Leave the third blank — it’s calculated automatically.
Read the result, shown in several units.
Average vs instantaneous speed
This calculator finds average speed — total distance divided by total time. Your instantaneous speed (what a speedometer shows) can be higher or lower at any moment; the average smooths it over the whole journey.
Speed Calculator FAQ
How do I calculate speed?
Divide the distance by the time: speed = distance ÷ time. Covering 100 km in 2 hours is 50 km/h. This calculator does it and converts to mph and m/s.
How do I calculate distance from speed and time?
Multiply speed by time: distance = speed × time. Travelling at 60 mph for 2 hours covers 120 miles.
How do I calculate time from distance and speed?
Divide distance by speed: time = distance ÷ speed. A 400 km trip at 80 km/h takes 5 hours.
How do I convert km/h to mph?
Multiply km/h by about 0.6214. To go the other way, multiply mph by 1.609. The calculator shows all units at once.
What’s the difference between average and instantaneous speed?
Average speed is total distance over total time; instantaneous speed is what a speedometer reads at one moment. This tool calculates average speed.
Is the speed calculator free?
Yes, this speed calculator is completely free, needs no sign-up, and gives instant results in your browser.
