Velocity & Acceleration Calculator
Free kinematics calculator — solve final velocity, acceleration, or displacement with the constant-acceleration equations.
Everyday Uses
Braking distances
How far does a car travel while stopping from highway speed? Kinematics answers precisely.
Physics homework
All three SUVAT solve modes with unit conversions — the daily bread of mechanics class.
0–100 analysis
Convert acceleration claims into g-forces and distances to compare cars meaningfully.
Free fall estimates
Drop time and impact speed from any height using a = 9.81 m/s².
Frequently Asked Questions
What equations does this calculator use?
The constant-acceleration (SUVAT) equations: v = u + at (final velocity), a = (v − u)/t (acceleration), and s = ut + ½at² (displacement), where u is initial velocity, v final velocity, a acceleration, t time, and s displacement. They apply whenever acceleration is constant — free fall, uniform braking, launch ramps.
How do I handle deceleration and direction?
Pick a positive direction and stay consistent: deceleration is simply negative acceleration. A car braking from 30 m/s at −5 m/s² reaches 0 in 6 seconds, covering 90 m. Downward motion under gravity uses a = −9.81 m/s² if up is positive.
What is acceleration in g units?
Dividing acceleration by 9.81 m/s² expresses it as multiples of Earth's gravity. A sports car hitting 100 km/h in 4 s pulls about 0.71 g; fighter jet turns reach 9 g; a car crash can exceed 30 g. It's an intuitive scale for how forces feel to a human body.
When do these equations NOT apply?
When acceleration changes over time — air resistance at high speed, rocket thrust as fuel burns, or jerky stop-and-go motion. Those need calculus or numerical methods. For short intervals or averaged behavior, constant-acceleration results remain a good approximation.