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.
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.
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.
How This Speed Calculator Works
Fill in any two of distance, time, and speed, choosing whichever units suit your numbers, and leave the value you want to solve for blank. The calculator works out the missing value using the relationship speed = distance / time, and shows the result converted into km/h, mph, and m/s. Everything runs in your browser, and nothing you enter is saved or sent anywhere.
The Three Ways to Rearrange the Formula
The same relationship between distance, time, and speed can be rearranged three ways depending on which value you’re solving for: speed = distance / time, distance = speed × time, or time = distance / speed. This calculator detects which two values you’ve entered and automatically applies the correct version of the formula.
Why Unit Conversion Matters
Distance, time, and speed can each be entered in different units — kilometres or miles, hours or seconds, km/h or mph. Before doing any math, the calculator converts everything to a common base (metres, seconds, and metres per second) internally, then converts the final answer back into readable units, so you never have to convert anything by hand.
Understanding Pace vs. Speed
When solving for speed from a distance and time, the calculator also shows your pace — the time it takes to cover one kilometre at that constant speed. Pace is simply the inverse of speed, and runners and cyclists often find it more intuitive than a raw speed figure, since it directly answers “how long will each kilometre take.”
Average Speed vs. Instantaneous Speed
This calculator finds average speed over the entire distance and time you enter — it doesn’t account for speeding up, slowing down, or stopping along the way. For a journey with varying speed, the result represents the constant speed that would have covered the same distance in the same total time.
Common Uses for a Speed Calculator
People reach for a speed calculator to plan a road trip’s arrival time, work out how fast a runner or cyclist actually needs to move to hit a target finish time, check whether a vehicle was travelling within a legal limit given distance and time, or simply convert a speed they already know into a different unit. Because it solves for whichever value is missing, the same tool covers all of these without needing separate calculators for each direction.
Frequently Asked Questions
Which two values do I need to enter?
Any two of distance, time, and speed. Leave the third one blank, and the calculator solves for it automatically.
What if I enter all three values?
The calculator only uses distance and time to solve for speed when all three are filled in. Clear the value you actually want calculated to see the correct result.
Is this average speed or top speed?
Average speed. It treats the entire distance as covered at one constant speed, regardless of any speeding up or slowing down along the way.
What is “pace” and how does it differ from speed?
Pace is the time needed to cover one kilometre at a given speed — the inverse of speed. It’s commonly used in running and cycling instead of a raw speed figure.
Does this calculator store any of my information?
No. Everything runs in your browser and nothing you enter is saved or sent anywhere.
You may also find our Pace Calculator or Time Calculator useful.