Calculate acceleration in m/s² from initial and final velocity over time, or from force and mass with automatic unit conversions for common units.
Related Calculators
Acceleration Formula
The acceleration calculator uses two common formulas, depending on the values you enter.
Acceleration from velocity and time:
a = (v_f - v_i) / t
- a = acceleration, measured in meters per second squared (m/s²)
- v_f = final velocity
- v_i = initial velocity
- t = time
Acceleration from force and mass:
a = F / m
- a = acceleration, measured in meters per second squared (m/s²)
- F = force, measured in newtons (N)
- m = mass, measured in kilograms (kg)
In the velocity and time mode, the calculator finds how quickly velocity changes over a given time period. It converts velocity inputs to meters per second and time inputs to seconds before calculating the result.
In the force and mass mode, the calculator uses Newton’s second law. It converts force to newtons and mass to kilograms, then divides force by mass to find acceleration.
Common Acceleration Unit Conversions
These conversions are used to put values into standard SI units before calculating acceleration.
| Quantity | Input Unit | Conversion to SI Unit |
|---|---|---|
| Velocity | km/h | 1 km/h = 0.27778 m/s |
| Velocity | mph | 1 mph = 0.44704 m/s |
| Time | minutes | 1 min = 60 s |
| Time | hours | 1 h = 3600 s |
| Force | lbf | 1 lbf = 4.44822 N |
| Mass | lb | 1 lb = 0.453592 kg |
Acceleration Result Meanings
| Result | Meaning |
|---|---|
| Positive acceleration | Velocity is increasing in the positive direction. |
| Negative acceleration | Velocity is decreasing, or acceleration is in the opposite direction of motion. |
| Zero acceleration | Velocity is not changing. |
| 9.8 m/s² | Approximate acceleration due to gravity near Earth’s surface. |
Example Acceleration Calculations
Example 1: Acceleration from velocity and time
You start at 5 m/s and reach 25 m/s in 10 seconds.
a = (25 - 5) / 10
a = 20 / 10 = 2 m/s^2
The acceleration is 2 m/s².
Example 2: Acceleration from force and mass
A force of 100 N acts on a mass of 20 kg.
a = 100 / 20
a = 5 m/s^2
The acceleration is 5 m/s².
FAQ
What unit does the acceleration calculator return?
The result is returned in meters per second squared, written as m/s². This means the velocity changes by that many meters per second every second.
Can acceleration be negative?
Yes. Negative acceleration means the final velocity is less than the initial velocity, or the acceleration is acting in the opposite direction of the positive direction you chose. It is often called deceleration when an object is slowing down.
Why must time and mass be greater than zero?
Time cannot be zero in the velocity formula because division by zero is undefined. Mass must be greater than zero in the force and mass formula because an object with zero mass cannot be used in a = F / m.
