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Free fall calculator

Compute the fall time and impact velocity of an object dropped from a height.

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Need Fall time (s), Impact velocity (m/s)? The Free fall calculator derives it from Height (m), Gravity (m/s²) in one step. For instance, with Height (m) = 20 and Gravity (m/s²) = 9.81 it returns Fall time (s) = 2.019 and Impact velocity (m/s) = 19.809.

How to use it

  1. Enter your values: Height (m), Gravity (m/s²).
  2. Read the result instantly: Fall time (s), Impact velocity (m/s).

Frequently asked questions

What does the Free fall calculator actually compute?

It takes Height (m) and Gravity (m/s²) and derives Fall time (s) and Impact velocity (m/s) from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

2 values: Height (m) and Gravity (m/s²). Nothing else is required — no account, no file upload.

Can you show a worked example?

With Height (m) = 20 and Gravity (m/s²) = 9.81, the calculator returns Fall time (s) = 2.019 and Impact velocity (m/s) = 19.809. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Height (m) = 22 and Gravity (m/s²) = 19.62 instead, Fall time (s) goes from 2.019 to 1.498 — which is why it is worth testing a few scenarios rather than trusting a single figure.

What does it give for smaller values?

Scaled down to Height (m) = 18 and Gravity (m/s²) = 4.91, Fall time (s) comes out at 2.708. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Checking a homework answer, sizing something before building it, and getting an order of magnitude before committing to a design — a torque on a bolt, the force a spring returns, the frequency a circuit resonates at, how long light takes to arrive.

What is the most common mistake?

Feeding in a value in the wrong unit. Physics formulas assume SI throughout, so grams instead of kilograms or centimetres instead of metres shifts the answer by powers of ten without any warning.

What is the difference between the Free fall calculator and the Potential energy calculator?

This one returns Fall time (s) and Impact velocity (m/s); the Potential energy calculator returns Potential energy (J). That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Acceleration calculator is the closest one after this: Compute acceleration from the change in velocity over time.

What else is worth having open alongside it?

Displacement calculator and Pendulum period calculator — they come up in the same task often enough to be worth a second tab.

Further reading

All guides →
GuideThe Four Kinematics Equations: Which One to Use, and What Each One Leaves OutFive variables, four equations, and each equation is missing exactly one of them. Choose by looking at the variable the question never mentions.ExplainerProjectile Motion Explained: Range, Height, Flight Time — and Why 45° Is Not Always BestThree formulas cover the whole of projectile motion on level ground. The catch is level ground: the moment launch and landing heights differ, the 45° result stops being true.ExplainerHow Buoyancy Works: Archimedes' Principle, and Why Ice Floats With 10.5 % Above WaterThe upward force equals the weight of the fluid pushed aside. That one sentence decides whether something floats, and if it floats, exactly how much of it stays under.ExplainerWhat Is Kinetic Energy? The KE = ½mv² Formula ExplainedKinetic energy is the energy of motion, given by KE = ½mv². Learn what the formula means, why speed matters most, and see worked examples in joules.ExplainerWhat Is Horsepower? Mechanical hp, Metric PS, and kWHorsepower measures the rate of doing work. Learn where the unit came from, how mechanical hp differs from metric PS/CV, and how both relate to kilowatts.ExplainerHow the Doppler Effect Works: The Formula, the Sign Convention, and Why Moving the Source Is Not the Same as Moving the ListenerFor sound, f' = f(v + v_o)/(v − v_s) — and getting the signs backwards is the classic error. Here is the convention spelled out, a 440 Hz source computed at four speeds, and why light needs a different equation entirely.