Free fall calculator
How long an object takes to fall and how fast it hits the ground, without air resistance.
How it works
h = v0 t + g t² / 2, so t = (−v0 + √(v0² + 2gh)) / g. Impact speed v = √(v0² + 2gh).
Results are for guidance only and do not replace professional advice.
Worked example
With the default values:
- Drop height (m)20
- BodyEarth (9.81 m/s²)
- Initial downward speed (m/s)0
you get:
- Fall time2.02 s
- Impact speed19.81 m/s (71.3 km/h)
- Distance in the last second14.9 m
- Same as a car crash at71 km/h
Frequently asked questions
How does the “Free fall calculator” tool work?
h = v0 t + g t² / 2, so t = (−v0 + √(v0² + 2gh)) / g. Impact speed v = √(v0² + 2gh).
What do I need to enter?
Just fill in: drop height, body, initial downward speed. The result updates as you type.
Can you give an example?
Drop height (m): 20; Body: Earth (9.81 m/s²); Initial downward speed (m/s): 0 → Fall time: 2.02 s; Impact speed: 19.81 m/s (71.3 km/h).
Is this calculator free, and is my data private?
Yes. HOD Calc is completely free with no sign-up. The calculation runs in your browser: nothing you type is sent or stored.