Acceleration Calculator
Acceleration is the rate at which velocity changes: how quickly something speeds up or slows down. This calculator finds it four ways, depending on what you actually know: from a velocity change over time, from velocities and distance, from distance and time, or from force and mass via Newton’s second law.
Results are reported in meters per second squared, feet per second squared, and g-force, so a car’s 0–60 time and a rocket launch can be compared on the same scale. The sign carries the direction: positive means speeding up in your chosen direction, negative means slowing down.
Acceleration Calculator
Four methods. Pick the one that matches the numbers you have.
| In m/s² | — |
| In ft/s² | — |
| In g-force | — |
| — | — |
| — | — |
These formulas assume constant (uniform) acceleration in a straight line. Real vehicles and falling objects with air resistance need more detailed models.
The four acceleration formulas
All four methods answer the same question from different knowns. With velocities and time: a = (v − u) / t. With velocities and distance: a = (v² − u²) / 2d. With distance and time: a = 2(d − ut) / t². With force and mass: a = F / m, which is Newton’s second law rearranged. Pick whichever method matches the numbers in your problem; they agree with each other when the acceleration is constant.
Worked example
A car goes from rest to 27.8 m/s (100 km/h) in 5 seconds. Velocity change = 27.8 − 0 = 27.8 m/s. Acceleration = 27.8 / 5 = 5.56 m/s², which is 18.24 ft/s² or 0.567 g. Enter these numbers with the velocity/time method to confirm.
G-force reference
| Scenario | Typical acceleration |
|---|---|
| Standing still | 1 g (gravity) |
| Car braking hard | 0.8–1 g |
| 0–60 mph in 6 s | about 0.46 g |
| Roller coaster launch | 1–1.5 g |
| Fighter jet maneuver | up to 9 g |
Frequently asked questions
What is the difference between acceleration and velocity?
Velocity is how fast something moves; acceleration is how fast that velocity changes. Cruising at a steady 60 mph means high velocity but zero acceleration.
Can acceleration be negative?
Yes. Negative acceleration means the velocity vector points opposite your chosen positive direction, which is usually slowing down. Braking is negative acceleration if forward is positive.
What units is acceleration measured in?
The SI unit is meters per second squared (m/s²). Feet per second squared is common in US engineering, and g-force (multiples of 9.80665 m/s²) describes what a body feels.
When do I use a = F/m instead?
Use Newton’s second law when you know the net force and the mass but not the motion details, for example sizing a motor or checking whether a structure can handle a load. Remember it must be the net force, not just one of several forces.
Does this work for curved paths?
No. These formulas assume straight-line motion with constant acceleration. On a curve there is also centripetal acceleration toward the center, which needs a separate calculation.