Acceleration Calculator
Enter any three of starting velocity, final velocity, acceleration and time to get the fourth, with the distance covered — 0 to 100 km/h, braking and more.
Answer
- Distance covered (s)
- 125 m
a = (v − u) ÷ t
- Given (in base units): u = 0 m/s, v = 27.7778 m/s, t = 9 s
- a = (v − u) ÷ t = 3.08642 m/s²
- s = (u + v) ÷ 2 × t = 125 m
Values
Fill in any 3; leave the one to work out empty.
How is this calculated?
a = (v − u) ÷ t; v = u + a × t; u = v − a × t; t = (v − u) ÷ a. Distance covered: s = (u + v) ÷ 2 × t.Runs in your browser — nothing you enter leaves this device.
About this tool
What it does
Acceleration Calculator works with motion in a straight line at a steady acceleration: the change in velocity divided by the time it takes, a = (v − u) ÷ t. Enter any three of starting velocity, final velocity, acceleration and time and the fourth is worked out, along with the distance covered on the way, s = (u + v) ÷ 2 × t. That answers questions such as how hard a car accelerates from 0 to 100 km/h in 9 seconds, how long a train takes to stop from 120 km/h at a given braking rate, or what speed a cyclist reaches after accelerating for 5 seconds. Velocities can be entered in km/h, mph, m/s, ft/s or knots; acceleration in m/s², ft/s² or multiples of standard gravity (g). Slowing down is a negative acceleration, and the page checks the signs make sense together.
How to use it
- Enter three of the four values with their units. Use a minus sign for braking.
- Leave the fourth empty; it and the distance covered are worked out.
- Change the acceleration unit to g to see it as a g-force.
- Read the working below the answer. Clear all starts again.
Limits and your data
- It assumes the acceleration is constant throughout. Real cars accelerate harder in low gears and less near top speed, so the result is the average acceleration.
- Motion is along one line. Velocities in opposite directions need opposite signs; for motion in two dimensions, treat each direction separately.
- If the acceleration would have to reverse the motion to reach the final velocity — for example from 20 m/s forward to 10 m/s backward — the distance shown is the net displacement, not the total path.
- Braking distances here ignore reaction time. Add the distance travelled before the brakes come on (speed × reaction time) for a stopping distance.
- The calculation runs in your browser and nothing is sent or stored.
Questions
What is the acceleration of a car doing 0–100 km/h in 9 seconds?
About 3.09 m/s², or 0.31 g, averaged over the run — the page opens with this example. It covers about 125 m while doing it.
How do I calculate deceleration?
Enter the starting speed, the final speed (0 for a stop) and the time. The acceleration comes out negative: that is the deceleration. From 30 m/s to rest in 5 s is −6 m/s².
How do I find the time to stop?
Enter the starting speed, a final speed of 0 and the braking acceleration as a negative number, and leave time empty. From 30 m/s at −6 m/s² takes 5 s and 75 m.
What is 1 g of acceleration?
Standard gravity, 9.80665 m/s² — the acceleration of a dropped object without air resistance. Choose g as the acceleration unit to read or enter it.