Solve distance from fall time or fall time from distance with d = ½·g·t² — metric & imperial, Moon/Mars gravity, impact velocity, and a 1–10 s reference table. Free, no sign-up, 100% client-side.
The most-searched question about free fall is a simple lookup: how far do you fall in 1 second? 3 seconds? 5 seconds? Here it is, on Earth, from rest, ignoring air resistance. Distance grows with the square of time — doubling the time quadruples the distance.
| Time | Distance (m) | Distance (ft) | Impact velocity |
|---|
A stone falls for 3 seconds. How far?
d = ½ × 9.80665 × 3² = 0.5 × 9.80665 × 9
= 44.13 m (144.78 ft)
You drop a rock off a 100 m cliff and hear it land. How long?
t = √(2 × 100 / 9.80665) = √20.3943
= 4.52 s
Same 3-second drop on the Moon (g = 1.62):
d = ½ × 1.62 × 9 = 7.29 m — only ⅙ of Earth's 44.13 m.
= 7.29 m
Free fall distance comes from the second equation of motion under constant acceleration, with initial velocity zero:
Assumptions, stated explicitly: the object is dropped from rest (initial velocity 0), gravity is constant over the fall, and there is no air resistance (vacuum).
This calculator assumes a vacuum, so its distance is the theoretical maximum for a given time (and its time is the minimum for a given distance). In real air, drag slows the falling object, and beyond a few seconds the object approaches terminal velocity — about 53 m/s (≈120 mph) for a skydiver in a belly-to-earth position. Past that point, extra seconds add distance linearly, not quadratically. For drops under ~2 seconds, the vacuum formula is very close to reality.
The keyword fall distance calculator fall protection deserves an honest note: in fall protection, free fall distance has a narrower meaning — the vertical distance a worker falls before the fall-arrest system begins to stop the fall. OSHA limits it to 6 ft (1.8 m) in general industry. The total fall clearance a safety plan needs is: free fall distance + deceleration distance + harness stretch/elongation + a safety margin below the worker. This tool computes the physics free fall (no arrest system at all) — related, but not the same quantity a safety plan certifies.
The free fall distance formula is d = 1/2 × g × t², where d is the distance fallen, g is the acceleration due to gravity (9.80665 m/s² on Earth), and t is the fall time in seconds. It assumes the object is dropped from rest with no air resistance.
In 1 second of free fall on Earth you fall about 4.90 meters (16.09 feet), calculated as 0.5 × 9.80665 × 1². Air resistance would make the real-world distance slightly less.
In 3 seconds of free fall on Earth you fall about 44.13 meters (144.78 feet), calculated as 0.5 × 9.80665 × 3². Distance grows with the square of time, so 3 seconds is 9 times farther than 1 second.
In 5 seconds of free fall on Earth you fall about 122.58 meters (402.19 feet), calculated as 0.5 × 9.80665 × 5². That is roughly the height of a 40-storey building.
Falling 100 meters in free fall on Earth takes about 4.52 seconds, from t = √(2 × d / g) = √(200 / 9.80665). The impact velocity would be about 44.3 m/s (159 km/h or 99 mph).
Free fall is motion under the influence of gravity alone, with no other forces such as air resistance acting on the object. The object must be dropped from rest, not thrown. In a vacuum, a feather and a bowling ball fall at exactly the same rate.
This calculator uses standard Earth gravity g = 9.80665 m/s² (32.174 ft/s²). You can also switch to presets for the Moon (1.62), Mars (3.71), Venus (8.87), or Jupiter (24.79), or type any custom gravity value.
No. In free fall without air resistance, all objects accelerate at the same rate regardless of mass — Galileo's famous result. A 1 kg ball and a 10 kg ball dropped together hit the ground at the same time. Mass only matters once air resistance is significant.
Rearrange the free fall formula to t = √(2 × d / g). For example, a 45-meter drop on Earth takes √(90 / 9.80665) = 3.03 seconds. Use the Time from distance mode of this calculator for any height.
Yes. This calculator assumes a vacuum, so its distance is the theoretical maximum for a given time (and its time is the minimum for a given distance). In air, drag slows the object, eventually capping speed at terminal velocity — about 53 m/s (120 mph) for a skydiver in belly-to-earth position.
Yes. Select the Moon, Mars, Venus, or Jupiter preset in the gravity field, or enter a custom g value. On the Moon (g = 1.62 m/s²), 3 seconds of free fall covers only 7.29 meters versus 44.13 meters on Earth.
Free fall distance is how far the object has dropped (d = 1/2 × g × t²), while free fall velocity is how fast it is moving (v = g × t). Distance grows quadratically with time; velocity grows linearly. Our free-fall-velocity tool covers speed in depth.
In fall protection, free fall distance has a narrower meaning: the vertical distance a worker falls before the fall-arrest system begins to stop the fall. OSHA limits it to 6 feet (1.8 m) in general industry. This is related but not identical to the physics free fall distance computed by this tool, which assumes no arrest system at all. This page is educational context only, not safety advice.
No and yes. This calculator runs 100% in your browser — your numbers never leave your device and nothing is uploaded. It is completely free with no sign-up.
This tool covers free-fall kinematics: distance and time (d ⇄ t) from rest, in a vacuum. It intentionally does not cover:
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