Free Fall Calculator
Free fall is motion under gravity alone. Drop something from a height and it speeds up by about 9.8 metres per second every second. This page works out how long the fall takes, and the speed at the end.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
The time to fall is the square root of twice the height, divided by gravity. Gravity at the surface of the Earth is about 9.81 metres per second squared.
The final speed is the square root of twice gravity times the height. Both figures ignore air resistance, so they fit dense objects falling short distances best.
Worked example
Dropped from 100 ft, an object falls for about 2 s and is moving at roughly 54.694 mph when it lands.
Questions
Does air slow a falling object?
Yes. Air resistance pushes back, more so for light, large objects, and it limits the speed in a long fall. This page leaves it out.
Does the mass change the time?
Not in this model. Without air, all objects fall at the same rate, however heavy they are.
Why is a real fall a little slower?
Air resistance grows with speed, so a real object reaches a lower top speed than this calculation gives.
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