- 1Enter the Initial Speed and Final Speed in metres per second (m/s).
- 2Enter the Time in seconds (s) over which the speed changed. It must be greater than zero.
- 3Read the Calculated Acceleration in m/s² below, along with the velocity change Δv.
The Acceleration Calculator finds the average acceleration of an object from how much its speed changed and how long the change took. Acceleration is the rate of change of velocity: a value of 3 m/s² means the speed increases by 3 metres per second every second. It is used for vehicle 0–100 figures, physics problems and motion analysis. A negative result means the object is slowing down (deceleration); zero means the speed held steady.
The single calculation performed: the change in speed divided by the elapsed time.
a = (v_final − v_initial) ÷ tShown alongside the result.
Δv = v_final − v_initialFollows directly from the formula.
v_final > v_initial → a > 0 (speeding up); v_final < v_initial → a < 0 (slowing down); equal → a = 0a = (27.78 − 0) ÷ 4.5 = 27.78 ÷ 4.5 ≈ 6.17a = (0 − 30) ÷ 6 = −30 ÷ 6 = −5a = (20 − 12) ÷ 4 = 8 ÷ 4 = 2- All speeds must be in m/s and time in seconds; the result is then in m/s². Convert km/h to m/s by dividing by 3.6 before entering.
- Time must be greater than zero. A zero or negative time shows 'Time must be greater than zero' and no result.
- A negative acceleration is not an error — it means the object slowed down over the interval.
- This is the average acceleration across the whole interval, not the instantaneous value at any instant.
- Initial and final speed may be negative if you are tracking direction along a line; the formula still applies.
How is acceleration calculated?
As the change in speed divided by the time taken: a = (final speed − initial speed) ÷ time.
What does a negative acceleration mean?
The final speed is lower than the initial speed — the object is decelerating. The magnitude is how quickly it slows.
What happens when acceleration is zero?
Initial and final speed are equal, so the object moved at constant speed during the interval.
What units does the calculator expect?
Metres per second (m/s) for both speeds and seconds (s) for time, giving acceleration in metres per second squared (m/s²).
Why do I get no result?
Time was zero, negative or blank, or one of the fields is not a number. Time must be greater than zero.