📐 Average Velocity Calculator
Find average velocity from displacement and time (v = Δx/Δt), or solve for the displacement or the time taken.
Average velocity v
5 m/s
Average velocity = displacement ÷ time (v = Δx/Δt). Average acceleration works the same way: a = Δv/Δt. 🔒 Computed in your browser.
How the average velocity calculator works
Average velocity is total displacement divided by the time taken: v = Δx/Δt. Enter any two of velocity, displacement and time and the tool solves for the third. Average acceleration follows the same pattern: a = Δv/Δt. Because displacement is a vector, the average velocity carries a sign: a positive result means net motion one way, a negative result the other. Note that the average over a trip is generally not the simple average of the starting and ending velocities, that shortcut only holds when the acceleration is constant.
Average velocity uses displacement (straight-line change in position), not the total distance travelled. They differ if the path isn’t straight. For instantaneous, changing motion, use the SUVAT solver.
Frequently asked questions
How do I calculate average velocity?
Divide the displacement by the time: v = Δx/Δt. Travelling 100 m in 20 s gives an average velocity of 5 m/s.
What is the difference between average velocity and average speed?
Average velocity uses displacement (net change in position, a vector); average speed uses total distance travelled. They match only for straight-line motion without reversing.
How is average acceleration calculated?
The same way with velocity: a = Δv/Δt, the change in velocity over the time interval.
When should I use SUVAT instead?
When acceleration is constant and you want final velocity, displacement or time from other quantities, use the kinematic (SUVAT) equations. Average velocity is just Δx/Δt over an interval.
Can average velocity be zero?
Yes, if you return to your start point, the displacement is zero, so the average velocity is zero even though you moved.
Can I just average two velocities?
Not in general. Average velocity is total displacement ÷ total time, so add up the displacements and divide by the total time. Averaging two velocity values only works when the acceleration is uniform, or when equal times are spent at each velocity.
Worked example: a two-leg journey
Drive 60 km east in 1 h, then 30 km east in 0.5 h. Total displacement is 90 km east over 1.5 h, so the average velocity is 90 ÷ 1.5 = 60 km/h east, found from the totals, not by averaging the leg speeds.
What units does average velocity use?
Any distance-over-time unit, metres per second (m/s) in SI, or km/h, mph and so on. Keep the displacement and time in matching units and the result comes out in those.
What is the difference between average and instantaneous velocity?
Average velocity is displacement over a whole interval; instantaneous velocity is the value at a single moment, the limit as the interval shrinks to zero. A speedometer shows instantaneous speed, while this tool gives the average over the trip.
What does a negative average velocity mean?
It means the net displacement points in the direction you have chosen as negative, the object ended up on the opposite side of its start. The sign only indicates direction, not that anything moved backwards.