What is Free Fall?
In free fall, an object moves under the influence of gravitational force only. The only acceleration acting on it is the acceleration of gravity g. No other force — including air resistance — affects a true free-falling object.
Interestingly, an object in free fall doesn't necessarily need to be moving downwards. For example, the Moon's motion satisfies all free-fall conditions: only gravity acts on it and there is no air resistance in space.
Free Fall Formulas
When an object is dropped (or thrown downward with initial velocity v₀), two equations describe the motion:
v = v₀ + g × t
h = v₀ × t + ½ × g × t²
If you know the height instead of the time, use:
v = √(v₀² + 2 × g × h)
Where g = 9.80665 m/s² (metric) or g = 32.17405 ft/s² (imperial).
Step-by-Step Example
A stone is dropped from rest (v₀ = 0) from a building. How fast is it going and how far has it fallen after 3 seconds?
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Final velocity:
v = 0 + 9.80665 × 3 = 29.42 m/s (≈ 105.9 km/h) -
Distance fallen:
h = 0 × 3 + ½ × 9.80665 × 3² = 44.13 m
Example: Highest Free Fall in History
On October 14, 2012, Felix Baumgartner jumped from a helium balloon at 38,969 m (127,852 ft) above Earth's surface. During the fall, he reached a peak speed of 1,357.64 km/h (843.9 mph) — breaking the sound barrier. His fall lasted approximately 4 minutes 19 seconds of free fall before opening his parachute.
How to Use This Calculator
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Choose your calculation mode:
- From time — enter fall duration to find velocity and distance
- From height — enter height/distance to find velocity and time
- Select unit system: Metric (m, m/s) or Imperial (ft, ft/s).
- Optionally enter an initial velocity (v₀) if the object was thrown downward rather than simply dropped. Leave at 0 for a dropped object.
- Enter the time (seconds) or height (m or ft).
- Click Calculate to see velocity and distance in multiple unit conversions.
Gravitational Acceleration Values
g = 9.80665 m/s²
Standard gravity (SI)
g = 32.17405 ft/s²
Standard gravity (US)
FAQs
What is free fall acceleration?
Free fall acceleration (g) is approximately 9.80665 m/s² near Earth's surface. This means that every second, a falling object gains about 9.81 m/s of downward speed (in the absence of air resistance).
Do all objects fall at the same speed?
In a true vacuum (no air), yes — all objects fall at the same rate regardless of mass. This was demonstrated by Galileo and confirmed on the Moon by Apollo 15 astronauts, who dropped a hammer and a feather simultaneously and watched them land together.
What is terminal velocity?
In reality, air resistance opposes the fall. As speed increases, air drag increases until it equals gravity. At that point, acceleration stops and the object reaches terminal velocity. For a skydiver, this is roughly 53 m/s (190 km/h) in a spread-eagle position. This calculator assumes no air resistance (ideal free fall).
How many days/weeks/months old am I in free fall time?
Just kidding — but this calculator does handle very long fall times. In reality, any free fall on Earth is limited by the ground or terminal velocity. In space (like the Moon's orbit), free fall can continue indefinitely.
How do I calculate free fall from height instead of time?
Use the From height mode. Enter the height and the calculator uses
v = √(2 × g × h) (for v₀ = 0) to find velocity, then
t = v / g for the fall time.
What is the difference between free fall and projectile motion?
Projectile motion combines free fall (vertical) with horizontal motion at constant speed. A ball thrown horizontally is a projectile: gravity pulls it down (free fall component) while it travels forward. This calculator covers the vertical (free fall) component only.