Acceleration Calculator
Calculate acceleration from initial speed, final speed and time — in m/s², in g, and as km/h per second — with the distance covered.
How quickly speed changed, in m/s² and in g.
How the acceleration calculator works
Acceleration is the change in velocity divided by the time it took: a = (v − u) ÷ t. With constant acceleration the distance covered is the average speed times the time, (u + v) ÷ 2 × t. The calculator takes the speeds in km/h (or m/s in Detailed mode), converts, and reports the acceleration in m/s², as a multiple of g (9.80665 m/s²) and as km/h gained per second.
A car that reaches 100 km/h in 8 seconds accelerates at 3.5 m/s² — about 0.35 g. Braking is negative acceleration: enter a lower final speed.
Formula: a = (v − u) ÷ t · s = (u + v) ÷ 2 × t
Worked examples
| Inputs | Acceleration | Note |
|---|---|---|
| 0 → 100 km/h in 8 s | 3.472 m/s² | 3.47 m/s², 0.35 g |
| 0 → 100 km/h in 3 s | 9.259 m/s² | a supercar: 0.94 g |
| 100 → 0 km/h in 3.5 s (braking) | -7.937 m/s² | negative: −7.9 m/s² |
FAQFrequently asked questions
What is 1 g of acceleration?
9.80665 m/s² — the acceleration of free fall at the Earth's surface. A 0→100 km/h time of 2.8 s is about 1 g.
Why is braking negative?
Because the velocity falls. Acceleration is the rate of change of velocity, so slowing down is acceleration in the opposite direction.
How far does a car travel while accelerating?
Average speed × time. From 0 to 100 km/h in 8 s the average is 50 km/h (13.9 m/s), so about 111 m.
What is the formula with distance instead of time?
v² = u² + 2as, so a = (v² − u²) ÷ 2s. Use it when you know the distance but not the time.
Where these figures come from
- NIST — CODATA 2018 fundamental physical constants — G, g₀, R, c
- NIST Special Publication 811 — Guide for the use of the International System of Units — unit conversions
- The Engineering ToolBox — material properties — specific heats, expansion coefficients, densities
- National Measurement Institute — Australia's measurement authority
Last checked: September 2026. Constants are the CODATA 2018 values; formulas are the standard textbook forms.