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Free fall calculator

Calculate drop height, fall time, impact velocity and energy for a falling object.

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Output
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Free fall calculator
Paste a list of values and this tool works out the rest of a free-fall problem for each line: give it a drop height and it returns fall time and impact velocity, give it a fall time and it returns height and velocity, or give it an impact velocity and it returns height and time. Switch the "Known quantity" option to tell the tool what each line represents. It is built for physics homework, drop-test estimates, ballistics sanity checks and anyone who wants a quick answer without rearranging the kinematics equations by hand.
Gravity defaults to Earth's standard 9.80665 m/s², with Moon and Mars presets for off-world scenarios, or pick "Custom" and enter your own value — useful for a different planet, a centrifuge, or a textbook problem that specifies g directly. An initial velocity option models an object already moving downward when the drop starts, such as something thrown rather than released from rest. Length and velocity units convert automatically between metric and imperial, and entering a mass computes the potential energy released and the kinetic energy at impact, in joules. A progression table, at whatever time step you choose, breaks a single drop down second by second (or however fine you set it) so you can see height and velocity build up over the fall rather than only the final numbers.
Each line of input is treated independently, so a whole batch of drop heights, times or velocities processes in one pass — handy for comparing several scenarios side by side. Output can be plain text, one result per line, or a compact table; toggle the formulas line on or off depending on whether you want the underlying equations shown alongside the numbers.
Everything runs locally in your browser — nothing you paste in is uploaded or stored anywhere. Copy the result, download it as a .txt file, clear the input, or send the output straight back into the input to run it through another tool.
FAQ
What can I use as the known value?
Height, fall time or impact velocity — pick which one your input lines represent with the "Known quantity" option, and the tool computes the other two plus energy.
Does it account for air resistance?
No. It uses ideal free-fall kinematics (constant gravitational acceleration, no drag), which is accurate for dense objects over short falls but overstates speed for light or wide objects falling a long way.
How is the energy calculated?
Potential energy is mass × gravity × height, and kinetic energy at impact is ½ × mass × velocity². Set the mass option to 0 if you only need the kinematics.
What does the progression table show?
A row for height and velocity at every time step you set, from the start of the fall to the moment of impact, so you can see the motion build up rather than only the final result.
Is my data uploaded anywhere?
No. The calculator runs entirely in your browser — your input never leaves your device.