How do you calculate free fall distance?

To calculate free fall distance, use the formula d = ½gt², where g is gravitational acceleration (9.81 m/s² on Earth) and t is the time of fall. If the object has an initial downward velocity v₀, use d = v₀t + ½gt². For example, an object falling for 3 seconds on Earth: d = ½ × 9.81 × 3² = 44.1 meters.

How do you calculate free fall time?

To find the time of free fall from a known height, use t = √(2d/g), where d is the drop height and g is gravitational acceleration. For example, dropping from 100 meters on Earth: t = √(2 × 100 / 9.81) = 4.52 seconds. If the object has initial velocity v₀, use t = (-v₀ + √(v₀² + 2gd)) / g.

How do you calculate free fall velocity?

The impact velocity of a free-falling object can be found using v = √(2gd), where g is gravity and d is the drop height. Alternatively, from time: v = gt. For example, falling from 50 meters on Earth: v = √(2 × 9.81 × 50) = 31.3 m/s (about 113 km/h). With initial velocity: v = √(v₀² + 2gd).

How do you calculate free fall acceleration?

To find gravitational acceleration from free fall data, use g = 2d/t², where d is the distance fallen and t is the time elapsed. This is how Galileo first measured gravity experimentally. For example, if a ball falls 4.9 meters in 1 second, g = 2 × 4.9 / 1² = 9.8 m/s². With initial velocity, use g = 2(d - v₀t) / t².

What is the free fall speed on the Moon vs Earth?

The Moon's gravity is about 1.62 m/s², roughly one-sixth of Earth's 9.81 m/s². An object dropped from 10 meters takes 1.43 seconds on Earth but 3.51 seconds on the Moon. Impact speed on the Moon is 5.69 m/s versus 14.0 m/s on Earth. This calculator includes gravity presets for 11 celestial bodies including the Moon, Mars, and Jupiter.

Do heavier objects fall faster in free fall?

No. In true free fall (without air resistance), all objects fall at the same rate regardless of mass. This was demonstrated by Galileo and confirmed on the Moon during Apollo 15 when astronaut David Scott dropped a hammer and feather simultaneously — both hit the ground at the same time. Mass only matters when air resistance is a factor.

What is the difference between free fall and terminal velocity?

Free fall assumes no air resistance — the object accelerates continuously at g. Terminal velocity occurs when air drag equals gravitational force, so the object stops accelerating. A skydiver's terminal velocity is about 53 m/s (120 mph), while this calculator would predict 280 m/s from 4 km with no drag. The free fall model is accurate for short falls, dense objects, or vacuum conditions.

How do you calculate impact force from free fall?

Impact force depends on the deceleration distance (how quickly the object stops), not just the fall height. First find the impact velocity using v = √(2gd). Then use F = mv²/(2s), where m is mass and s is the stopping distance. For example, a 1 kg object falling 5 meters (v = 9.9 m/s) stopping over 0.01 m experiences about 4,905 N of force.

How long does it take to fall 100 feet?

100 feet is about 30.48 meters. Using t = √(2d/g) with Earth's gravity: t = √(2 × 30.48 / 9.81) = 2.49 seconds. The object hits the ground at about 24.4 m/s (54.7 mph or 87.9 km/h). These values assume no air resistance and zero initial velocity.

What are the free fall equations used in this calculator?

This calculator uses four kinematic equations: (1) d = v₀t + ½gt² for distance, (2) t = (-v₀ + √(v₀² + 2gd)) / g for time, (3) v = √(v₀² + 2gd) for impact velocity, and (4) g = 2(d - v₀t) / t² for gravitational acceleration. When v₀ = 0 (dropped from rest), these simplify to d = ½gt², t = √(2d/g), and v = √(2gd).

Free Fall Calculator

Find fall time from height and gravity

Height / Distance (d)

Result Unit (t)

Gravitational Acceleration (g)

Initial Velocity (v₀)

Fall Time (t)

4.516s

All Values

Complete kinematic values in SI base units

Fall Distance

100.00m

Fall Time

4.516s

Impact Velocity

44.287m/s

Gravity

9.807m/s²

Step-by-Step Solution

Calculation walkthrough with your values

1.Formula: t = sqrt(2d / g)

2.t = sqrt(2 × 100.00 / 9.8066)

3.t = 4.5160 s

Velocity Conversions

Impact velocity in all supported units

m/s44.2869

km/h159.4329

mph99.0670

ft/s145.2982

kn86.0869

Planet Comparison

Same drop height (100.0000 m) on other planets

Planet	g	Dist	Time	Speed
Moon	1.6	100.0	11.11s	18.0
Mars	3.7	100.0	7.33s	27.3
Jupiter	24.8	100.0	2.84s	70.4
Venus	8.9	100.0	4.75s	42.1
Mercury	3.7	100.0	7.35s	27.2
Saturn	10.4	100.0	4.38s	45.7

How the Free Fall Calculator Works

Core formulas for all four solve modes

Free fall describes the motion of an object under the sole influence of gravity, with no air resistance. This calculator uses the standard kinematic equations of motion to solve for any unknown variable given the others. All formulas support an optional initial downward velocity (v₀).

Distance

d = v₀t + ½gt²

Solve for d

Time

t = (-v₀ + √(v₀² + 2gd)) / g

Solve for t

Velocity

v = √(v₀² + 2gd)

Solve for v

Gravity

g = 2(d - v₀t) / t²

Solve for g

Example — Dropping from 100 m

Height

100

Gravity

9.807

m/s²

Time

4.515

Impact Speed

44.29

m/s

An object dropped from rest at 100 meters on Earth takes 4.515 seconds to reach the ground with an impact speed of 44.29 m/s (159.4 km/h).

What Is Free Fall?

Definition and physical meaning

Free fall is the motion of an object where gravity is the only force acting upon it. In a true free fall, there is no air resistance, thrust, or any other force — only gravitational acceleration pulling the object downward.

Key Variables

d — distance fallen (meters)

t — time of fall (seconds)

v — final velocity at impact (m/s)

g — gravitational acceleration (9.807 m/s² on Earth)

v₀ — initial velocity (0 if dropped from rest)

In true free fall, all objects fall at the same rate regardless of mass — Galileo demonstrated this at the Tower of Pisa (historically debated), and Apollo 15 astronaut David Scott confirmed it on the Moon by dropping a hammer and a feather simultaneously.

Free Fall Quick Reference

Common drop heights and their fall time and impact speed on Earth (v₀ = 0)

Scenario	Height	Time	Speed
Phone drop	1.5 m	0.55 s	19.5 km/h
One-story building	3 m	0.78 s	27.6 km/h
Diving board (10 m)	10 m	1.43 s	50.4 km/h
Cliff jump (20 m)	20 m	2.02 s	71.3 km/h
Niagara Falls	51 m	3.23 s	113.9 km/h
Statue of Liberty	93 m	4.36 s	153.8 km/h
Skydiver (4 km)	4,000 m	28.6 s	1008 km/h

Values assume no air resistance. Real-world speeds are lower due to drag, especially for long falls.

Key Considerations

Important notes for accurate free fall calculations

No air resistance assumed

These formulas model ideal free fall in a vacuum. In reality, air drag limits speed to terminal velocity (~53 m/s for a human, ~120 mph).

Gravity varies by location

Earth's g ranges from 9.764 m/s² (equator, high altitude) to 9.834 m/s² (poles). The standard value 9.80665 m/s² is the conventional average.

Constant acceleration only

These equations assume g is constant throughout the fall. For extreme heights (>100 km), gravity weakens with altitude and the inverse-square law applies.

Direction convention

All values are magnitudes (positive). Distance is measured downward from the drop point, and velocity is the speed in the downward direction.

Mass does not matter

In a vacuum, a feather and a bowling ball fall at exactly the same rate. Mass affects air resistance but not gravitational acceleration.

Frequently Asked Questions

Common questions and detailed answers

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Last updated May 2, 2026

Free Fall Calculator

All Values

Step-by-Step Solution

Velocity Conversions

Planet Comparison

How the Free Fall Calculator Works

What Is Free Fall?

Free Fall Quick Reference

Key Considerations

Frequently Asked Questions

Embed Free Fall Calculator

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