The basic kinematics question — how quickly is velocity changing — answered from an initial velocity, final velocity, and elapsed time.
How it works
Subtracting initial velocity from final velocity and dividing by the elapsed time gives acceleration.
What this does not include
This does not include distance traveled during that acceleration — for that, a separate kinematics equation involving displacement would be needed.
How to use this calculator
- Enter the initial velocity, final velocity, and time elapsed.
A worked example
Velocity goes from 0 to 20 m/s in 4 seconds → (20 − 0) ÷ 4 = 5 m/s².
Velocity drops from 30 to 10 m/s over 5 seconds → (10 − 30) ÷ 5 = −4 m/s² — a negative value, since the object is slowing down.
What the variables mean
| Variable | Meaning |
|---|---|
| Initial velocity | Speed at the start of the interval |
| Final velocity | Speed at the end of the interval |
| Time | Duration of the interval |
Edge cases worth knowing
A negative result means deceleration, not an error — acceleration is a signed quantity, and a drop in speed produces a negative value by design.
Zero time makes the calculation undefined — dividing a velocity change by a zero-length interval has no meaningful answer, so the calculator declines to show a result.
Frequently asked questions
What does a negative acceleration mean?
Deceleration — the object is slowing down, since final velocity is lower than initial velocity.
What units does this use?
Meters per second for velocity, seconds for time, and meters per second squared for the resulting acceleration — the standard SI units for kinematics.
Can acceleration be zero?
Yes — if final velocity equals initial velocity, there’s no change in speed over that time, so acceleration is zero (constant velocity).
