Free Fall Calculator: Time and Speed
This free fall calculator solves the classic physics problem of an object dropped or thrown straight down. Enter the height in feet or meters to get the fall time and impact speed, or enter a fall time to get the distance and final speed. You can add an initial downward velocity and change gravity for the Moon or Mars. It uses g = 32.174 ft/s² (9.80665 m/s²) and ignores air resistance, so it matches textbook answers. Speeds are shown in ft/s, mph, m/s and km/h.
Free Fall Calculator
Find how long an object falls, how fast it hits the ground, and how far it drops, ignoring air resistance.
How to use the Free Fall Calculator
- Choose to solve from height or from time.
- Enter the height or time and pick feet or meters.
- Optionally add an initial speed or pick another planet.
- Read the time, impact speed and distance.
Free fall equations
h = v₀t + ½gt² · v = v₀ + gt · t = (−v₀ + √(v₀² + 2gh)) ÷ g · g = 32.174 ft/s² = 9.80665 m/s²
Features
- Solve from height or time
- Feet and meters
- Earth, Moon and Mars gravity
- Speed in mph and km/h
Frequently asked questions
How long does it take to fall 100 feet?
About 2.49 seconds, using t = √(2h ÷ g) = √(200 ÷ 32.174), ignoring air resistance.
How fast does an object hit the ground from 100 feet?
About 80.2 ft/s, or 54.7 mph, using v = √(2gh).
What is the free fall formula?
Distance h = ½gt², speed v = gt, and time t = √(2h ÷ g), when dropped from rest.
Does a heavier object fall faster?
Not without air. All objects accelerate at the same g. In real air, light or wide objects slow down because of drag.
What is terminal velocity?
The top speed where air drag equals weight. A skydiver reaches about 120 mph. This calculator ignores drag, so it is accurate only for short, dense falls.