How do you calculate acceleration?

Subtract the starting speed from the final speed, then divide by the time taken: a = (v − v₀) ÷ t. A car going from rest to 60 mph in 9 seconds reaches 26.8224 m/s, so its acceleration is 26.8224 ÷ 9 = 2.98 m/s². Convert both speeds to the same unit before subtracting — mixing mph with m/s is the commonest mistake, and it produces an answer that is wrong by more than a factor of two.

What is the difference between speed and acceleration?

Speed is how fast you are going; acceleration is how fast your speed is changing. They are independent. A car cruising steadily at 100 km/h has high speed and zero acceleration. A car pulling away from lights has near-zero speed and high acceleration. You feel acceleration, not speed — which is why a smooth aircraft at 900 km/h feels like standing still, while a lift setting off at walking pace is unmistakable.

What does the area under a velocity-time graph mean?

It is the distance travelled. Multiply a speed by a time and you get a distance, which is exactly what an area on those axes represents. Under constant acceleration the shape is a trapezium, and its area is ½(v₀ + v)·t. That is why this expression and the more familiar v₀t + ½at² always agree — they measure the same shaded region two different ways. The slope of that same line, meanwhile, is the acceleration.

Can acceleration be negative?

Yes, and a negative sign is information rather than an error. It means the acceleration points opposite to the direction of travel, so the object slows down — everyday language calls this deceleration or braking. A car going from 100 km/h to a stop in 3.5 seconds has an acceleration of about −7.9 m/s². The magnitude is what matters for how violent it feels; the sign only records the direction.

What is g-force and how does it relate to acceleration?

G-force expresses acceleration as a multiple of standard gravity, which is exactly 9.80665 m/s². So 1 g is 9.81 m/s² and 2 g is 19.6 m/s². It is used in aviation, motorsport and aerospace because it describes what a body actually experiences. A brisk car launch is around 0.3 g, a roller coaster 4 to 5 g, and fighter pilots train to remain conscious at about 9 g. Enter any value in g-force here and it converts automatically.

How far does something travel while accelerating?

Use the average speed. Under constant acceleration the average of the starting and finishing speeds is simply their midpoint, so distance = ½(v₀ + v)·t. A car doing 0–60 mph in 9 seconds averages 13.41 m/s and therefore covers about 120.7 metres. The equivalent formula v₀t + ½at² gives the identical answer. Notice you cannot just multiply the final speed by the time — that would overstate the distance by a factor of two from rest.

What is the acceleration due to gravity?

Near Earth's surface a falling object accelerates at about 9.81 m/s², meaning it gains 9.81 metres per second of speed every second. The standard value is exactly 9.80665 m/s², and it varies slightly with latitude and altitude — a little stronger at the poles, a little weaker at the equator. Crucially it is the same for every object regardless of mass, which is why a hammer and a feather fall together in a vacuum.

How does acceleration relate to force?

Newton's second law connects them: F = ma, or rearranged, a = F ÷ m. Acceleration is proportional to the net force and inversely proportional to mass, so the same push produces half the acceleration on twice the mass. This is why a loaded truck pulls away so much more slowly than an empty one on the same engine, and why braking distance grows with load even when the brakes are unchanged.

Is real acceleration ever actually constant?

Rarely. This calculator assumes a steady rate, which is the standard model and is accurate enough for most problems, but real engines produce more force in some gear ranges than others, brakes fade as they heat, and air resistance grows with speed so acceleration tails off. Treat the result as the average across the interval. If you need the value at one specific instant rather than an average, that is instantaneous acceleration and it requires calculus.

Acceleration Calculator (a = Δv / Δt)

Calculate acceleration, final speed or time from a = Δv ÷ Δt — how quickly something changes speed. Enter any two of the three and this calculator returns the third, converts it into m/s², ft/s², g-force and km/h per second, and shows how it compares with everything from a lift setting off to a bull...

a = Δv / Δt

SOLVE FOR

INITIAL SPEED

FINAL SPEED

TIME TAKEN

EVERYDAY EXAMPLES

ACCELERATION

2.980 m/s²

G-FORCE

0.304

FT/S²

9.78

KM/H PER SEC

10.73

Speeding up by 2.98 m/s every second.

Initial speed

0.00 m/s

Final speed

26.82 m/s

Change in speed

26.82 m/s

Time

9.000 s

Distance covered

120.70 m

As g-force

0.304 g

STEPS

Convert to SI: v₀ = 0.0000 m/s, v = 26.8224 m/s, t = 9.0000 s

Find the change in speed: Δv = 26.8224 − 0.0000 = 26.8224 m/s

Divide by time: a = 26.8224 ÷ 9.0000 = 2.9803 m/s²

SPEED CHANGING OVER TIME

TIME

0.00 s

SPEED

0.0 m/s

DISTANCE

0.0 m

G-FORCE

0.30 g

Two readings of the same graph. The slope of the line is the acceleration — steeper means a faster change in speed. The area underneath it is the distance travelled, which is why ½(v₀ + v)·t and v₀t + ½at² always give the same answer: they are two ways of measuring one shaded trapezium. Here that area comes to 120.70 m.

HOW HARD IS THAT?

AT THIS RATE

0–60 mph would take

9.00 s

0–100 km/h would take

9.32 s

Speed gained in 1 s

2.98 m/s

Compared to gravity

0.304 × g

Live simulation · constant acceleration · updates as you type

Created with❤️byeaglecalculator.com

HOW TO USE

1
Choose what to find with the SOLVE FOR buttons: Acceleration, Final speed or Time. The fields change to ask for whichever quantities the calculation needs. Initial speed is always required.
2
Enter your values and pick units beside each field. Speeds in m/s, km/h, mph, ft/s or knots; time in seconds, minutes, hours or milliseconds; acceleration in m/s², ft/s², g-force, km/h per second or mph per second. Everything converts to SI before the maths runs.
3
Read the answer in the black box with three alternative units below, plus a plain-language line telling you whether the object is speeding up or slowing down and by how much each second. The key-facts grid adds the distance covered.
4
Watch the simulation. The markers on the track spread out when speeding up and bunch together when braking, and the shaded area under the velocity-time graph fills in as the distance accumulates. Drag the scrubber to freeze any instant.

THE FORMULAS

Accelerationa = (v − v₀) / t

Final speedv = v₀ + a t

Timet = (v − v₀) / a

Distance (area)d = ½(v₀ + v) t

Distance (kinematic)d = v₀t + ½at²

Without timev² = v₀² + 2ad

Newton’s second lawa = F / m

One g= 9.80665 m/s² exactly

FREQUENTLY ASKED QUESTIONS

RELATED CALCULATORS

SUVAT Equations Calculator

Calculate instantly →

Free fall 3m

Calculate instantly →

Velocity Calculator

Calculate instantly →

Free fall 0.5m

Calculate instantly →

MORE PHYSICS CALCULATORS

Projectile Motion Calculator

Calculate instantly →

Free Fall Calculator

Calculate instantly →

Force Calculator

Calculate instantly →

Free fall 0.5m

Calculate instantly →

Free fall 1m

Calculate instantly →

Free fall 1.5m

Calculate instantly →

Free fall 2m

Calculate instantly →

Free fall 3m

Calculate instantly →

Free fall 4m

Calculate instantly →

Free fall 5m

Calculate instantly →

Free fall 6m

Calculate instantly →

Free fall 7m

Calculate instantly →

Free fall 8m

Calculate instantly →

Free fall 9m

Calculate instantly →

Free fall 10m

Calculate instantly →

Kinetic Energy Calculator

Calculate instantly →

Potential Energy Calculator

Calculate instantly →

Velocity Calculator

Calculate instantly →

Ohm's Law Calculator

Calculate instantly →

Was this calculator helpful?

Last updated: July 28, 2026 · Formula verified · Eagle-eyed accuracy for every calculation.