Free Fall Calculator
Find how long an object falls, how fast it is moving on impact, and how far it travels when dropped from rest under gravity.
Known value
m
m/s²
Speed when hitting the ground
- 1
Fall time
√(2 × 45 ÷ 9.81) = 3.0289t = √(2h / g) - 2
Impact velocity
9.81 × 3.0289 = 29.71
How does this calculator work?
A free fall calculator finds fall time, impact velocity, and distance for an object dropped from rest. Enter the drop height (or time) and gravity g (default 9.81 m/s²). It uses t = √(2h/g), v = g·t, and h = ½·g·t², assuming no air resistance, to return the speed at impact.
Formula
How this is calculated
This calculator models an object released from rest (initial velocity zero) and falling under a constant gravitational acceleration g, ignoring air resistance. You choose what you know: the drop height h (in metres) or the fall time t (in seconds). The gravitational acceleration g defaults to 9.81 m/s² for Earth, but you can change it for other bodies such as the Moon (1.62) or Mars (3.71).
When you supply the height, the fall time is t = √(2h / g) and the impact velocity is v = √(2·g·h), which equals g·t. When you supply the time instead, the distance fallen is h = ½·g·t² and the impact velocity is simply v = g·t. The curve shows the position s(τ) = ½·g·τ² across the fall, which is the parabola characteristic of constant acceleration.
Results assume a vacuum and a uniform g, so they overestimate real speeds for light or large objects where drag matters, and they are only accurate over short drops where g stays roughly constant. Inputs must be non-negative; a zero or negative gravity is rejected because it has no physical meaning here.
Frequently asked questions
No. It assumes free fall in a vacuum with constant gravity, so real-world impact speeds for light or non-aerodynamic objects will be lower once drag and terminal velocity are considered.
Change the gravity value g. The Moon is about 1.62 m/s², Mars about 3.71 m/s², and Jupiter about 24.79 m/s². The formulas remain the same.
Because v = g·t and v = √(2·g·h) describe the same motion. Entering height computes the matching time, and entering time computes the matching height, so the impact speed is consistent.
Also known as
TG we-Calculate Editorial Team. (2026). Free Fall Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/free-fall-calculator
TG we-Calculate Editorial Team. "Free Fall Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/free-fall-calculator.
TG we-Calculate Editorial Team, "Free Fall Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/free-fall-calculator
@misc{wecalculate_free_fall_calculator, title = {Free Fall Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/free-fall-calculator}}, year = {2026}, note = {TG we-Calculate} }
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