🪂 Free Fall Calculator
Solve free fall from rest: enter a drop height, time or impact speed and get the others, with gravity you can change for the Moon or Mars.
Impact speed v
29.7086 m/s
Free fall from rest: v = gt, h = ½gt², v = √(2gh). g = 9.80665 m/s² on Earth (editable). 🔒 Computed in your browser.
How the free fall calculator works
An object dropped from rest accelerates at g. The equations are v = gt, h = ½gt², and v = √(2gh). Enter any one of height, time or impact speed (with g, default 9.80665 m/s²) and the tool solves the rest.
Distinct “drop height / fall time / impact speed” intent. Change g to model the Moon (1.62) or Mars (3.72). Ignores air resistance, so real objects hit a terminal velocity and land slower.
Frequently asked questions
How do I calculate the time to fall a given height?
From h = ½gt², t = √(2h/g). Dropping 45 m on Earth takes √(90/9.8) ≈ 3.03 s. Enter the height and the tool computes the time.
How fast is something going when it lands?
v = √(2gh), or v = gt. From 45 m, v ≈ 29.7 m/s (ignoring air resistance). Enter height or time to get the impact speed.
Does free fall depend on mass?
No, in the absence of air resistance, all objects fall at the same rate. A feather and a hammer land together in a vacuum.
What is g?
The acceleration due to gravity: about 9.80665 m/s² on Earth. It differs elsewhere, 1.62 on the Moon, 3.72 on Mars, which you can select.
Why is my real-world answer different?
Air resistance slows real falls and caps them at a terminal velocity, so actual impact speeds are lower than the ideal free-fall value for light or slow objects.
Worked example: a 20 m drop
From h = ½gt², t = √(2×20/9.81) ≈ 2.02 s, and the impact speed v = gt ≈ 19.8 m/s (or v = √(2gh) ≈ 19.8 m/s), ignoring air resistance.
Does this assume the object starts from rest?
Yes, free fall here means released from rest, with initial velocity zero. If the object is thrown down or up with a starting speed, use the SUVAT kinematics calculator, which accepts an initial velocity u.