About the Velocity Calculator
This velocity calculator uses the speed–distance–time relationship v = d / t. Pick the quantity you want to find, enter the other two in whatever units you have — metres, kilometres, miles or feet; seconds, minutes or hours; m/s, km/h, mph or ft/s — and it returns the answer in your chosen unit plus the equivalent in all the common units.
It is handy for physics homework, planning a drive or a run, working out how long a trip takes at a given speed, or checking the average speed of a race. Students can use it to see the same result expressed in SI units and everyday units side by side.
The result is an average: it assumes constant speed in a straight line (or the average over the whole trip). For motion with acceleration, use the kinematics (SUVAT) calculator instead. Velocity technically includes direction; here we work with its magnitude, the speed.
With the default inputs, the answer (in your selected unit) is 80. Change any value above to recalculate instantly.
How to use the velocity calculator
- 1Choose whether to solve for velocity, distance or time.
- 2Enter the two known values.
- 3Select the units for distance, time and velocity.
- 4Read the answer in your chosen unit, plus conversions to m/s, km/h and mph.
Formula and method
Average velocity (speed) is the distance travelled divided by the time taken. Rearranging gives distance = velocity × time and time = distance ÷ velocity, so any two values determine the third.
Before dividing or multiplying, the calculator converts everything to SI units (metres, seconds, m/s) using exact factors — 1 mile = 1,609.344 m, 1 foot = 0.3048 m, 1 km/h = 1/3.6 m/s — and then converts the answer back into the unit you selected. The result is an average over the trip and assumes the motion is along a path whose length equals the distance entered.
- v
- Average velocity (speed)
- d
- Distance travelled
- t
- Elapsed time
Worked examples
Average speed of a road trip
Driving 100 km in 1.25 hours means an average of 100 ÷ 1.25 = 80 km/h, which is 22.22 m/s or about 49.7 mph.
How far in 45 minutes at 65 mph
45 minutes is 0.75 hours, so the distance is 65 × 0.75 = 48.75 miles, or about 78.46 km.
Time to run 5 km at 3 m/s
5,000 m ÷ 3 m/s = 1,666.7 seconds, which is about 27.8 minutes (27 min 47 s).
Frequently asked questions
What is the formula for velocity?+
Average velocity is displacement divided by time: v = d / t. If you travel 150 m in 30 s, your average velocity is 5 m/s. Rearranged, distance = velocity × time and time = distance ÷ velocity.
What is the difference between speed and velocity?+
Speed is how fast something moves; velocity is speed in a specific direction, so it is a vector. Running a full lap of a track gives a positive average speed but zero average velocity because you end where you started.
How do I convert m/s to km/h?+
Multiply metres per second by 3.6 to get kilometres per hour, and divide by 3.6 to go back. For miles per hour, multiply m/s by about 2.23694.
How is average speed different from the average of speeds?+
Average speed is total distance over total time. Driving 60 km at 60 km/h and another 60 km at 30 km/h gives 120 km in 3 hours — 40 km/h, not the 45 km/h you get by averaging the two speeds.
What if the object is accelerating?+
This tool gives the average over the trip. To find final velocity or distance under constant acceleration, use the kinematics (SUVAT) calculator, which uses equations such as v = u + at.