Free Fall Calculator
Find how long something falls and how fast it lands, ignoring air resistance. Choose to start from a drop height (m or ft) or a fall time (seconds) to get the fall duration, impact speed in m/s and mph, and the distance covered.
Example: with Start from Drop height · Drop height 50 · Height unit m (meters) · Fall time (seconds) 3 → Impact speed: 31.32 m/s (70.1 mph).
- Fall time3.19 s
- Distance fallen50.0 m (164.0 ft)
- What that impact is likeHighway-speed impact — serious damage
Computed by the calculator below using its default values. Change any input to see your own numbers.
In free fall under gravity alone, h = ½gt² and impact speed v = √(2gh) = gt, with g = 9.80665 m/s². Speed builds steadily until air resistance — left out here — starts to matter.
How falling speed builds
In free fall, gravity pulls every object downward with the same acceleration, about 9.81 meters per second every second. Speed therefore grows in a straight line with time — after 1 second you fall at nearly 10 m/s, after 2 seconds nearly 20 m/s. Distance grows faster still, with the square of time, because you spend each later second moving quicker than the last.
That is why the two headline formulas are h = ½gt² for distance and v = √(2gh) for the speed at the bottom. Drop something twice as far and it does not land twice as fast — it lands about 1.4 times as fast, since speed follows the square root of height.
Where air resistance takes over
These equations assume a vacuum. In real air, drag grows with speed and eventually cancels gravity, capping the fall at a terminal velocity — around 120 mph for a belly-to-earth skydiver. For dense, compact objects over short drops, air makes little difference and these numbers are close.
For light or fluffy objects, or falls lasting more than a couple of seconds, the vacuum speeds here overestimate reality. A feather and a hammer fall together only where there is no air; add an atmosphere and shape starts to rule.
How it’s calculated
Free fall under constant gravity g = 9.80665 m/s², starting from rest. From a height: v = √(2gh), time t = √(2h/g). From a time: distance = ½gt², v = gt. Heights convert at 1 ft = 0.3048 m; speed is shown in m/s and mph (÷0.44704).
Ignores air resistance and buoyancy, and assumes the object starts from rest. Real falls slow as drag builds, so beyond roughly one to two seconds the true speed is lower than shown.
Free fall: height, time, and impact speed (in a vacuum)
| Drop height | Fall time | Impact speed |
|---|---|---|
| 1 m (3.3 ft) | 0.45 s | 4.4 m/s (9.9 mph) |
| 10 m (33 ft) | 1.43 s | 14.0 m/s (31 mph) |
| 50 m (164 ft) | 3.19 s | 31.3 m/s (70 mph) |
| 100 m (328 ft) | 4.52 s | 44.3 m/s (99 mph) |
| 300 m (984 ft) | 7.82 s | 76.7 m/s (172 mph) |
Computed with h = ½gt² and v = √(2gh), g = 9.80665 m/s², ignoring air resistance.
Common mistakes
- Assuming double the height means double the speed — impact speed scales with the square root of height.
- Forgetting air resistance on long or lightweight falls, where terminal velocity caps the real speed.
- Mixing up the formulas: distance uses ½gt², while speed uses gt or √(2gh).
- Giving the object a starting speed; these formulas assume it is released from rest.
Frequently asked questions
What is the free fall formula?
Distance fallen is h = ½gt² and impact speed is v = √(2gh) = gt, where g is 9.80665 m/s² and t is the fall time. These hold when air resistance is ignored.
How fast is something going after falling a given height?
Take the square root of 2 times g times the height. From 50 meters that is √(2 × 9.81 × 50) ≈ 31 m/s, or about 70 mph, in the absence of air resistance.
Do heavy and light objects fall at the same rate?
In a vacuum, yes — gravity accelerates them equally. In air, drag slows lighter and fluffier objects more, so a feather drifts while a coin drops quickly.
Does this account for air resistance?
No. It models ideal free fall in a vacuum. For compact objects and short drops it is close, but long falls approach a terminal velocity that these formulas do not include.
How long does it take to fall a certain distance?
Use t = √(2h/g). For 100 meters that is √(200 / 9.81) ≈ 4.5 seconds, ignoring air resistance.