Free Fall Calculator - Distance, Velocity & Time

How to use this tool

Enter the known value (height, time, or velocity).
The other two quantities are calculated automatically.

Free fall formulas

Distance: h = ½ × g × t²
Velocity: v = g × t
Velocity from height: v = √(2 × g × h)

Free fall formulas reference

Formula	Solves for	Given
h = ½gt²	Distance fallen	Time and g
v = gt	Final velocity	Time and g
v² = 2gh	Final velocity	Distance and g
t = √(2h/g)	Time to fall	Distance and g

Gravitational acceleration reference

Body	g (m/s²)	Compared to Earth
Earth (standard)	9.81	1× baseline
Moon	1.62	~1/6 of Earth
Mars	3.72	~0.38× Earth
Venus	8.87	~0.91× Earth
Jupiter	24.8	~2.5× Earth

Terminal velocity

In free fall, objects continuously accelerate only in a vacuum. In the real atmosphere, air resistance increases with speed until it equals the gravitational force - at that point the object stops accelerating and falls at a constant terminal velocity. For a human in belly-to-earth skydiving position, terminal velocity is approximately 195 km/h (120 mph). In a head-down dive position, it can reach 290 km/h (180 mph).

Air resistance vs. vacuum

In a vacuum, all objects fall at the same rate regardless of mass - a feather and a hammer fall identically. This was famously demonstrated by Galileo (conceptually) and confirmed live by Apollo 15 astronaut David Scott on the Moon in 1971, who dropped a hammer and a falcon feather simultaneously; both hit the lunar surface at the same time.

Gravitational acceleration

Earth surface: 9.81 m/s² (32.17 ft/s²). The Moon: 1.62 m/s². Mars: 3.72 m/s². Change the g value in the calculator to explore other worlds.

Frequently asked questions

What is free fall?

Free fall is motion under only the influence of gravity, with no air resistance. Near Earth's surface, objects accelerate downward at g ≈ 9.81 m/s² (32.17 ft/s²).