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Acceleration Calculator

Reviewed by the CalculatorHub team, edited by James Graham. Formulae from NIST SP 330 (SI Units). Last verified 14 June 2026.

Acceleration measures how quickly velocity changes over time. This calculator supports two common methods. The kinematic method uses a = (v - u) / t: enter the initial velocity (u, m/s), final velocity (v, m/s), and time elapsed (t, s) to find the average acceleration. The Newton's Law method uses a = F / m: enter the net force acting on an object (N) and its mass (kg). Both methods output acceleration in metres per second squared (m/s²). Standard gravitational acceleration on Earth is g = 9.81 m/s², used as a reference in the results. The kinematic formula assumes constant (uniform) acceleration throughout the time interval. If acceleration varies, it gives only the average over that period. The Newton's Law formula gives the instantaneous acceleration at any moment, provided the net force and mass are known. Common applications include vehicle performance analysis, physics homework, structural load calculations, and sports science. Results display to two decimal places in standard US number format.

Acceleration: -- m/s²

a = (v - u) / t or a = F / m. g on Earth = 9.81 m/s². Source: NIST SP 330, as at 14 June 2026.

Starting speed in m/s
Ending speed in m/s
Seconds elapsed
Acceleration --
In m/s²--
Multiples of g--

Formulae

Kinematic: a = (v - u) / t
Newton's Law: a = F / m
Earth gravity: g = 9.81 m/s²

Worked example (kinematic)

A car accelerates from rest (u = 0) to 27.78 m/s (100 km/h) in 8 s:

  1. a = (27.78 - 0) / 8
  2. a = 3.47 m/s²
  3. In multiples of g: 3.47 / 9.81 = 0.35 g

Worked example (Newton's Law)

A 1,200 kg car has a net force of 4,800 N applied:

  1. a = 4,800 / 1,200
  2. a = 4.00 m/s²

Frequently asked questions

What is acceleration?

Acceleration is the rate of change of velocity with respect to time. It is a vector quantity, meaning it has both magnitude and direction. An object accelerates whenever its speed changes, its direction changes, or both. The SI unit of acceleration is metres per second squared (m/s²). Positive acceleration means speeding up in the chosen positive direction; negative acceleration (deceleration) means slowing down or speeding up in the negative direction.

What is the formula a = (v - u) / t?

This is the kinematic formula for average acceleration under constant acceleration. Here, v is final velocity (m/s), u is initial velocity (m/s), and t is the time elapsed (s). The numerator (v - u) is the change in velocity. Dividing by time gives the rate of that change. This formula assumes acceleration is constant throughout the time interval.

How does a = F/m relate to Newton's Second Law?

Newton's Second Law is F = m * a. Rearranging gives a = F / m. This tells us that for a given force, a larger mass results in less acceleration, and for a given mass, a larger force results in more acceleration. Force is in newtons (N), mass in kilograms (kg), and the result is acceleration in m/s².

What is g (gravitational acceleration)?

The standard gravitational acceleration at Earth's surface is g = 9.80665 m/s², often rounded to 9.81 m/s² for calculations. This is the acceleration experienced by any freely falling object near Earth's surface (ignoring air resistance). It is defined by the International Bureau of Weights and Measures (BIPM). Gravitational acceleration varies slightly by location, being slightly higher at the poles and slightly lower at the equator and at altitude.

Can acceleration be constant if speed is constant?

An object moving in a circle at constant speed still has acceleration because its direction is constantly changing. This is called centripetal acceleration, directed toward the centre of the circle. So acceleration being zero requires both constant speed and constant direction (i.e., straight-line motion at constant speed).

Sources

Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. General information only.