Physics
Free-Fall Calculator
Compute how long it takes to fall from a height and what the impact velocity will be using the standard gravity equations.
Drop height and optional initial velocity to get impact time and speed (ignoring drag).
Free fall
h = v₀ t + ½ g t² v = v₀ + g t
The calculator assumes downward positive acceleration (g). Initial velocity can be zero or any downward speed.
How to use
- Enter the drop height, optional initial velocity, and gravitational acceleration (9.81 m/s² by default).
- Hit calculate to get time to impact and terminal speed in m/s and mph.
Example
Input: Height = 20 m, v₀ = 0, g = 9.81 m/s²
Output: Time ≈ 2.02 s, Impact velocity ≈ 19.8 m/s (≈ 44 mph)
Student-friendly breakdown
This walkthrough emphasizes the most searched ideas for Free-Fall Calculator: Free-Fall Calculator. Start with the formula above, then follow the guided steps to double-check your work. For quick revision, highlight the givens, plug into the equation, and finish by verifying your units.
Need more support? Use the links below to open the long-form guide, browse additional examples, or hop into adjacent calculators within the same topic — each one is a quick way to double-check your work or handle a related question without starting from scratch.
Deep dive & study plan
Free-Fall Calculator: Drop time and impact velocity from any height (no drag). It's built around free fall, gravity, kinematics, so you can go from a raw question to a checked answer without switching tools.
The math behind it: The calculator assumes downward positive acceleration (g). Initial velocity can be zero or any downward speed. The core relationship is h = v₀ t + ½ g t² v = v₀ + g t, shown above the calculator so you can see exactly how your inputs turn into the result.
To use it well: (1) Enter the drop height, optional initial velocity, and gravitational acceleration (9.81 m/s² by default). (2) Hit calculate to get time to impact and terminal speed in m/s and mph. Keep your units consistent as you go, and re-run a case you already know the answer to — it's the fastest way to catch a typo before it throws off a result you're relying on.
Worked example: entering Height = 20 m, v₀ = 0, g = 9.81 m/s² returns Time ≈ 2.02 s, Impact velocity ≈ 19.8 m/s (≈ 44 mph). Try swapping in your own numbers next, especially a case you're unsure about, before you use this for something that matters.
Quick retention checklist
- Speak the formula aloud (or annotate it) so the relationships stick.
- Write each step in your own words and compare with the numbered list above.
- Swap in new numbers for the Example to make sure the calculator (and your logic) handles edge cases.
- Check at least one related calculator below — it's the fastest way to confirm your numbers still line up from a different angle.
FAQ & notes
Can I model upward throws?
Enter the upward speed as the initial velocity—time to impact will include the ascent and descent phases.
Does it include air resistance?
No. For more accurate predictions of real-world drops, incorporate drag or use a CFD/ballistics tool.
What formula does the Free-Fall Calculator use?
The calculator assumes downward positive acceleration (g). Initial velocity can be zero or any downward speed.
How do I use the Free-Fall Calculator?
Enter the drop height, optional initial velocity, and gravitational acceleration (9.81 m/s² by default). Hit calculate to get time to impact and terminal speed in m/s and mph.