Free Fall Distance Calculator
Enter any two of the four free-fall variables (distance, time, final velocity, or initial velocity) and this calculator solves the rest instantly. Switch between metric and imperial units, choose a gravity preset for Earth, the Moon, Mars, or enter a custom value, and step through the worked math line by line. A chart plots distance and speed over the full duration of the fall.
What is free fall?
Free fall describes the motion of an object under the sole influence of gravity, with no other forces (such as air resistance, thrust, or buoyancy) acting on it. Every object in free fall accelerates at the same rate regardless of its mass, a result confirmed by Galileo Galilei in the late sixteenth century and later formalised by Isaac Newton. On Earth that rate is approximately 9.807 m/s^2 downward. The Moon, Mars, and other bodies each have a different surface gravity, so the same drop height produces very different fall times and impact speeds.
The free fall equations
Three kinematic equations cover all free fall scenarios. Distance: h = v0 * t + 0.5 * g * t^2, where h is the distance fallen, v0 is the initial downward velocity, g is gravitational acceleration, and t is time. Velocity: v = v0 + g * t, where v is the final speed. Velocity-distance: v^2 = v0^2 + 2 * g * h, which eliminates time and is useful when only distance and speed are known. This calculator applies whichever equation is appropriate based on the quantity you ask it to solve for, and shows every substitution in the "Show your work" panel.
How to use this calculator
Select which variable you want to solve for from the "Solve for" dropdown. The input fields change to show exactly the values you need to enter. Choose a gravity preset (Earth, Moon, Mars, Jupiter) or enter a custom acceleration. Switch between metric (metres, m/s) and imperial (feet, ft/s) at any time, the result updates instantly. The chart below the result plots how both distance and speed build through the entire fall, and the worked-steps panel shows the arithmetic with your exact numbers substituted in.
Air resistance and terminal velocity
Real objects experience air drag that opposes their motion, growing stronger as speed increases. Eventually drag balances gravity and acceleration stops - the object reaches terminal velocity. For a skydiver this is roughly 55 m/s (about 200 km/h) in a belly-to-earth position. A feather reaches terminal velocity almost immediately. This calculator models ideal free fall only and gives an upper bound on fall speed. For accurate drag modelling, use a projectile-motion tool with a drag coefficient and cross-sectional area.
Free fall on Earth from rest - every second
| Time (s) | Distance fallen (m) | Distance fallen (ft) | Speed (m/s) | Speed (km/h) |
|---|---|---|---|---|
| 1 | 4.9 | 16.1 | 9.8 | 35.3 |
| 2 | 19.6 | 64.4 | 19.6 | 70.6 |
| 3 | 44.1 | 144.8 | 29.4 | 105.8 |
| 4 | 78.5 | 257.5 | 39.2 | 141.1 |
| 5 | 122.6 | 402.3 | 49 | 176.4 |
| 6 | 176.6 | 579.4 | 58.9 | 212 |
| 7 | 240.3 | 788 | 68.7 | 247.3 |
| 8 | 313.8 | 1029.3 | 78.5 | 282.5 |
| 9 | 397.1 | 1302.3 | 88.3 | 317.8 |
| 10 | 490.3 | 1608.8 | 98.1 | 353.1 |
Distance and speed accumulated each second when dropped from rest under standard Earth gravity (9.807 m/s^2), ignoring air resistance.
Frequently asked questions
How far does an object fall in 3 seconds?
On Earth, an object dropped from rest falls 0.5 * 9.807 * 3^2 = 44.1 metres (about 144.7 feet) in exactly 3 seconds, and reaches a speed of 9.807 * 3 = 29.4 m/s (about 96.5 ft/s or 105.8 km/h) at that moment.
Does mass affect how fast an object falls?
In ideal free fall (no air resistance), mass has no effect. All objects accelerate at the same rate under gravity alone, which is why a hammer and a feather fall at the same speed in a vacuum. In practice, air resistance depends on the drag coefficient and cross-sectional area relative to mass, so a feather reaches terminal velocity much sooner than a bowling ball.
What is the difference between free fall and projectile motion?
Free fall refers specifically to vertical motion under gravity with no other forces. Projectile motion is the more general case where an object also has a horizontal velocity component. The vertical part of a projectile follows the same free fall equations, while the horizontal part is constant-velocity (ignoring air drag).
What is terminal velocity?
Terminal velocity is reached when the upward drag force equals the downward gravitational force, giving zero net force and therefore zero acceleration. Speed stays constant from that point on. For a skydiver in a belly-to-earth position it is roughly 55 m/s (around 200 km/h). Streamlined objects reach a higher terminal velocity; very light objects with large surface areas reach it almost instantly.
How does gravity differ on the Moon, Mars, and other planets?
Gravity depends on the mass and radius of a body. The Moon has about 1/6 of Earth's surface gravity (1.62 m/s^2), so an object takes about 2.5 times longer to fall the same distance. Mars has about 38% of Earth's gravity (3.72 m/s^2). Jupiter's gravity is about 2.53 times Earth's (24.8 m/s^2), so objects fall much faster there. Use the gravity preset selector to compare fall distances and times across bodies.