Acceleration Calculator
Find acceleration from change in velocity over time.
Results update as you type.
How it works
Acceleration measures how quickly an object's velocity changes, and this acceleration calculator finds it from the starting velocity, the final velocity, and the time the change took. The answer, in metres per second squared, tells you how many metres per second the object gains or loses each second. Acceleration is central to almost every motion problem. It links force to motion through Newton's second law, F = ma, so knowing an object's acceleration lets you find the force acting on it or predict how its speed evolves. Car makers quote nought-to-sixty times, which are acceleration figures; engineers design brakes around deceleration; and physics students use acceleration to connect the equations of motion. A quick acceleration calculator removes the arithmetic and the sign errors. The formula works because acceleration is defined as the change in velocity divided by the time over which it happens. A positive result means the object is speeding up in the direction of motion, while a negative result signals deceleration or acceleration in the opposite direction. Because velocities can be negative, this acceleration calculator handles objects that reverse direction too, making it a reliable tool for homework, lab reports, and real-world motion analysis alike.
a = (v_f − v_i) ÷ t
Acceleration is the rate at which velocity changes, so it equals the change in velocity divided by the time taken for that change. Subtracting the initial velocity from the final velocity gives how much the speed changed, and dividing by the elapsed time spreads that change evenly across the interval to give the average acceleration. The formula works because acceleration is defined as the slope of the velocity-time graph, and over any interval that slope is simply the rise in velocity over the run in time.
Source:Standard physics (kinematics, average acceleration)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter initial velocity, final velocity and time taken.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Acceleration updates instantly as you type — no button to press.
Frequently asked questions
What does a negative acceleration mean?
A negative acceleration means the velocity is decreasing in the direction you defined as positive, commonly called deceleration or braking. It can also mean the object is accelerating in the opposite direction. The sign always depends on your chosen positive direction, so a car slowing down while moving forward shows negative acceleration, as does one speeding up while moving backward. Context tells you which situation applies.
Why is acceleration measured in metres per second squared?
Acceleration is a change in velocity, measured in metres per second, divided by time, measured in seconds. Dividing metres per second by seconds gives metres per second per second, written metres per second squared. This unit tells you how many metres per second of speed the object gains during each second. Earth's gravity, for reference, produces an acceleration of about 9.81 m/s² on falling objects.
Is this average or instantaneous acceleration?
This calculator gives average acceleration over the whole time interval, because it uses the total change in velocity divided by the total time. If the acceleration was constant throughout, the average equals the instantaneous value at every moment. If the acceleration varied, the result is the single steady value that would have produced the same overall change in velocity across that interval.
How do I find the force from acceleration?
Use Newton's second law, F = m × a, multiplying the object's mass in kilograms by the acceleration you calculated here. The result is the net force in newtons required to produce that acceleration. This is one of the most useful links in mechanics, connecting the kinematics of motion to the dynamics of the forces causing it, and it works in any consistent set of units.
What if the time entered is zero?
If the time is zero the calculation is undefined, because you cannot divide a change in velocity by zero time; the calculator returns a dash to signal this. Physically, an instantaneous change in velocity would require infinite acceleration and infinite force, which is impossible. Enter the actual non-zero duration over which the velocity changed to obtain a meaningful average acceleration value.