Uniform Acceleration Calculator
Motion under constant acceleration — enter any three of initial velocity, final velocity, acceleration, time and distance, and the other two follow from the SUVAT equations.
Five quantities, five equations, each missing one of them.
How the uniform acceleration calculator works
Five quantities, five equations, each missing one of them. Enter three and the page picks the equation that needs exactly those and solves for the rest.
The classic use is braking: a car at 100 km/h decelerating at 7 m/s² stops in 55 metres and 4 seconds. Double the speed and the distance quadruples — the v² term is why speed limits matter more than they feel like they should.
Formula: v = u + at; s = ut + ½at²; v² = u² + 2as
Worked examples
| Inputs | Distance (m) | Note |
|---|---|---|
| Braking from 100 km/h at 7 m/s² | 55.203 | 55 m in 4 s |
| Free fall for 3 s | 44.13 | 44 m, 29 m/s |
| A runway | 1,600 | the acceleration needed |
FAQFrequently asked questions
What are the SUVAT equations?
Five relations between displacement, initial and final velocity, acceleration and time for constant acceleration. Each omits one quantity, so three knowns always determine the rest.
Why does braking distance go with the square of speed?
Because kinetic energy does, and the brakes remove it at a roughly constant rate. Twice the speed is four times the energy and four times the distance.
Which sign convention?
Pick a positive direction and keep it. A car braking has positive velocity and negative acceleration, as in the default example.
Does this apply to free fall?
Yes, with acceleration 9.81 m/s² downward and air resistance ignored. It holds well for dense objects over short drops.
What if I enter inconsistent values?
The page says so. Four or five knowns over-determine the motion; if they disagree, the first three entered are used and the rest are ignored.
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 Physical Laboratory — the UK's national measurement institute
Last checked: September 2026. Constants are the CODATA 2018 values; formulas are the standard textbook forms.