Acceleration CalculatorFrom velocity and time, distance, or force and mass, in m/s² and g
Pick the data you have, get acceleration with every step shown, and see it as g-force and as an equivalent 0–100 km/h time.
By Manzoor Ahmad, pharmacist · Updated How do you calculate acceleration?
Acceleration = change in velocity ÷ time: a = (v − u) ÷ t. A car going from 0 to 100 km/h (27.78 m/s) in 6.0 s accelerates at 27.78 ÷ 6.0 = 4.63 m/s², which is 0.47 g. Without time, use a = (v² − u²) ÷ 2d, and from a net force use a = F ÷ m.
Acceleration formulas
The three kinematic forms assume constant acceleration. If acceleration varies, these give the average. Convert to g by dividing by 9.80665 m/s².
Worked examples
1. A car from 0 to 100 km/h
u = 0, v = 100 km/h = 27.78 m/s, t = 6.0 s. a = 27.78 ÷ 6.0 = 4.63 m/s² = 0.47 g. This is the calculator’s default.
2. Emergency braking
From 100 km/h to rest in 3.0 s: a = (0 − 27.78) ÷ 3.0 = −9.26 m/s², a deceleration of 0.94 g, close to the limit of good tyres on dry asphalt.
3. From distance only
A cart starts from rest and covers 100 m in 5 s: a = 2 × 100 ÷ 5² = 8 m/s². Its final speed is a × t = 40 m/s, which you can confirm with the final velocity calculator.
Typical accelerations and g-forces
| Situation | Acceleration | g-force |
|---|---|---|
| Passenger lift starting | ≈ 1 m/s² | 0.1 g |
| Family car, 0–100 km/h in 10 s | 2.8 m/s² | 0.28 g |
| Free fall on Earth | 9.81 m/s² | 1 g |
| Performance EV, 0–100 km/h in 2.1 s | 13.2 m/s² | 1.35 g |
| Space Shuttle launch (peak) | ≈ 29 m/s² | 3 g |
| Roller coaster loop (peak) | 30–50 m/s² | 3–5 g |
| Fighter jet hard turn | ≈ 88 m/s² | 9 g |
Acceleration FAQs
Average acceleration is a = (v − u) ÷ t, the change in velocity divided by the time taken. With v and u in m/s and t in seconds, acceleration is in m/s².
Subtract the starting speed from the final speed and divide by the time. A car going from 0 to 100 km/h (27.78 m/s) in 6.0 s accelerates at 27.78 ÷ 6.0 = 4.63 m/s².
If the object starts with speed u and covers distance d in time t at constant acceleration, a = 2(d − ut) ÷ t². Starting from rest, 100 m in 5 s means a = 2 × 100 ÷ 25 = 8 m/s².
Use a = (v² − u²) ÷ 2d. Accelerating from rest to 20 m/s over 50 m gives a = 400 ÷ 100 = 4 m/s².
g-force expresses acceleration as a multiple of standard gravity, 9.80665 m/s². An acceleration of 19.6 m/s² is 2 g. Fighter pilots can tolerate about 9 g briefly with special suits.
Negative acceleration means the velocity is decreasing in the chosen direction, commonly called deceleration. Braking from 27.78 m/s to 0 in 4 s is −6.94 m/s², about −0.71 g.
The SI unit is meters per second squared (m/s²). Other units include ft/s², km/h per second and g. 1 g = 9.80665 m/s² = 32.174 ft/s².
Yes. Acceleration has magnitude and direction. A car turning at constant speed is accelerating because its direction of motion is changing.
By Newton's second law, a = F ÷ m. A net force of 100 N on a 20 kg object produces 5 m/s² of acceleration.
Everyday cars reach 0–100 km/h in about 8–12 s (2.3–3.5 m/s²). Performance electric cars can do it in about 2–3 s (9–14 m/s², over 1 g).
Yes. The distance-based formulas assume acceleration is constant. For changing acceleration, the result is an average.
Most roller coasters peak between about 3 and 5 g for short moments at the bottom of drops and loops, which is why ride designers limit how long those forces last.
Sources
- OpenStax University Physics Volume 1, Section 3.3: Average and Instantaneous Acceleration
- OpenStax University Physics Volume 1, Section 3.4: Motion with Constant Acceleration
- NIST CODATA: Standard acceleration of gravity
- NASA: Human Integration Design Handbook (acceleration limits)
- NIST SP 811: Unit conversions
This acceleration calculator assumes constant acceleration in a straight line. Vehicle and human-tolerance figures are typical values for illustration.