Free Fall Calculator
Fill in either the height or the time of the fall, and leave the other blank.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Time = √(2 × height ÷ g)
- Speed at impact = g × time
- Height fallen = ½ × g × time²
- g = 9.80665 m/s² unless you change it
For the energy involved, see the potential energy calculator.
Worked example
A drop from 100 m:
- Time = √(200 ÷ 9.80665) = 4.52 s
- Speed = 9.80665 × 4.516 = 44.29 m/s, or about 159 km/h
Why your number may differ
Air resistance is ignored, so a real object reaches a lower speed. Gravity also varies slightly with place and altitude.
Frequently asked questions
What is free fall?
Motion under gravity alone, with no air resistance. The object speeds up by about 9.8 m/s every second.
Does the mass matter?
Not without air resistance. A heavy and a light object fall at the same rate. In real life air drag slows light, wide objects.
How accurate is it for real drops?
Good for short drops of compact objects. Over long falls, air resistance cuts the speed well below this ideal figure.