Free Fall & Gravity Calculator: what this tool is for
In classical physics, free fall describes the ideal motion of an object subjected solely to the gravitational pull of a celestial body, in the complete absence of aerodynamic drag or air resistance. First established by Galileo Galilei and famously corroborated on the Moon by Apollo 15 astronaut David Scott dropping a feather and a geology hammer, free fall exhibits a key universal principle: all objects accelerate at the exact same rate g regardless of their physical mass.
On Earth, the standard acceleration due to gravity at sea level is g = 9.80665 m/s² (commonly rounded to 9.81 m/s² or 32.174 ft/s²). The classic Newtonian kinematic equations governing uniform acceleration connect initial drop height h in meters, elapsed fall time t in seconds, and final ground impact velocity v in meters per second: h = 1/2 × g × t² and v = √(2 × g × h).
These kinematic laws reveal that distance traversed expands quadratically with time: after 1 second an object drops 4.9 meters, after 2 seconds 19.6 meters, and after 3 seconds 44.1 meters, while instantaneous speed builds by 35.3 km/h (21.9 mph) every single second.
This free online Free Fall Calculator enables you to instantly compute impact speed, elapsed drop duration, and initial height across Earth, Moon, Mars, and Jupiter, complete with step-by-step mathematical breakdowns and kinetic impact energy.
No file stored
Nothing is saved on our servers, during or after processing.
Local processing
The computation runs in your browser whenever the technology allows it.
Instant result
No waiting and no export queue: the result appears live.
Free, no account
No sign-up, no daily limit and no intrusive ads.
What this tool gives you
Omnidirectional kinematic solver
Solve for impact speed and duration from initial height (h), find drop height from elapsed time (t), or compute the height required to reach a specific velocity (v).
Multi-planet gravity simulator
Explore gravitational trajectories across Earth (9.81 m/s²), the Moon (1.62 m/s²), Mars (3.72 m/s²), Jupiter (24.79 m/s²), or input custom acceleration values.
Impact kinetic energy evaluation
Enter object mass to calculate peak destructive kinetic energy at ground impact (in Joules, kilojoules, and equivalent building stories).
Step-by-step chronology timeline
Track progression second by second with real-time velocity and distance tables throughout the entire descent.
Real-world examples
Examine free fall kinematic characteristics across Earth and other celestial worlds:
How to use Free Fall & Gravity Calculator
Select your starting variable
Choose whether you know Drop Height (h), Fall Duration (t), or Target Impact Speed (v).
Choose the gravitational field
Pick Earth (9.81 m/s²), the Moon, Mars, Jupiter, or configure a custom gravity parameter.
Input your figures and object mass
Enter the numerical magnitude and optionally specify mass to compute kinetic impact energy.
Review speed, time, and timeline
Inspect impact velocity, elapsed descent time, and the chronological second-by-second timeline table.
Tips and mistakes to avoid
Estimating well depth or cliff height with audio timing
Drop a stone and count elapsed seconds until hearing the splash/thud: depth is roughly h ≈ 5 × t² (e.g., 3 seconds yields about 5 × 3² = 45 meters). For high precision, deduct the time sound takes to travel back upward (340 m/s).
Torricelli's shortcut for impact speed
To find impact speed v directly without calculating intermediate fall duration, use v = √(2 × g × h). A 20-meter drop gives v = √(2 × 9.81 × 20) = √392.4 = 19.81 m/s (71.3 km/h).
Avoid : Believing heavier objects fall faster in vacuum
In a true vacuum, a bowling ball and a feather accelerate identically and hit the ground at the exact same instant. Only atmospheric drag slows lightweight or high-surface-area objects in air.
Avoid : Overlooking terminal velocity for high-altitude drops
This calculator assumes pure free fall without drag. In real air, a skydiver in belly-to-earth orientation hits terminal equilibrium speed (~200 km/h / 120 mph) after roughly 12 seconds (~450 m of drop).
Frequently asked questions
Answers to the questions people ask about Free Fall & Gravity Calculator.
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Updated on August 2026. See all tools