About the Acceleration Calculator
This acceleration calculator works out how quickly an object speeds up or slows down. Choose the velocity method to use a start speed, end speed and elapsed time (a = Δv ÷ t), or the force method to use Newton’s second law (a = F ÷ m). Speeds can be entered in m/s, km/h, mph or ft/s and are converted to SI units automatically.
It is useful for physics homework, checking a car’s 0–60 mph performance, estimating braking deceleration, or sizing forces in simple engineering problems. Alongside the acceleration in m/s² you also get the equivalent g-force, the change in velocity and the distance travelled during the time interval.
The calculator assumes constant (uniform) acceleration in a straight line. A negative result means the object is decelerating — its speed is falling in the chosen direction.
With the default inputs, the acceleration is 3.3528 m/s². Change any value above to recalculate instantly.
How to use the acceleration calculator
- 1Choose whether you know the velocity change or the force and mass.
- 2Pick the speed unit you want to type in (mph, km/h, m/s or ft/s).
- 3Enter the initial velocity and either the final velocity or the force and mass.
- 4Enter the time interval in seconds.
- 5Read the acceleration in m/s², ft/s² and g, plus the distance covered.
Formula and method
Average acceleration is the change in velocity divided by the time it took: a = (v − v₀) ÷ t. Velocities are first converted to metres per second, so the answer is in m/s². When you know the net force and mass instead, Newton’s second law rearranges to a = F ÷ m.
Distance travelled uses the constant-acceleration equation d = v₀t + ½at². The g-force figure divides the acceleration by standard gravity, 9.80665 m/s², so 1 g is the acceleration of an object in free fall near Earth’s surface.
- a
- Acceleration (m/s²)
- v₀
- Initial velocity (m/s)
- v
- Final velocity (m/s)
- t
- Elapsed time (s)
- F
- Net force (N)
- m
- Mass (kg)
Worked examples
Car going 0–60 mph in 8 seconds
60 mph is 26.8224 m/s. Dividing that change in speed by 8 seconds gives 3.35 m/s², about 0.34 g. Starting from rest, the car covers ½ × 3.3528 × 8² ≈ 107.3 m while accelerating.
Braking from 100 km/h to a stop in 3.5 s
100 km/h is 27.78 m/s. Losing all of that in 3.5 s is an acceleration of −7.94 m/s² — a deceleration of about 0.81 g. The car stops in roughly 48.6 m once the brakes are applied.
5,000 N on a 1,500 kg car
Using a = F ÷ m, 5,000 N ÷ 1,500 kg = 3.33 m/s². After 8 seconds from rest the car is moving at 26.7 m/s (about 96 km/h) and has travelled 106.7 m.
Frequently asked questions
What is the formula for acceleration?+
Acceleration equals the change in velocity divided by the change in time: a = (v − v₀) ÷ t. It can also be found from Newton’s second law as a = F ÷ m when the net force and mass are known.
What are the units of acceleration?+
The SI unit is metres per second squared (m/s²) — the number of metres per second the velocity changes each second. Feet per second squared (ft/s²) and g (multiples of 9.80665 m/s²) are also common.
Can acceleration be negative?+
Yes. Negative acceleration means the velocity is decreasing in the positive direction, which is usually called deceleration — for example, a car braking to a stop.
How do I convert acceleration to g-force?+
Divide the acceleration in m/s² by 9.80665. A car accelerating at 4.9 m/s² is pulling about 0.5 g; a fighter jet turning at 88 m/s² is pulling about 9 g.
What is the acceleration due to gravity?+
Near Earth’s surface objects in free fall accelerate at about 9.81 m/s² (32.2 ft/s²). The standard value used for defining g is exactly 9.80665 m/s².