Free Fall Calculator (drop height, time, impact speed)
Calculate how long something takes to fall, how far it falls, and how fast it lands, using g — enter a height or a time.
How long does it take to fall? (feet)
Fall time and impact speed from rest on Earth, ignoring air resistance. A fall of 200 ft takes about 3.53 secondsand lands at roughly 77.3 mph.
| Drop height | Metres | Fall time | Impact speed | Impact speed |
|---|---|---|---|---|
| 5 ft | 1.524 m | 0.558 s | 17.9 ft/s | 12.2 mph |
| 10 ft | 3.048 m | 0.788 s | 25.4 ft/s | 17.3 mph |
| 15 ft | 4.572 m | 0.966 s | 31.1 ft/s | 21.2 mph |
| 20 ft | 6.096 m | 1.12 s | 35.9 ft/s | 24.5 mph |
| 25 ft | 7.62 m | 1.25 s | 40.1 ft/s | 27.3 mph |
| 30 ft | 9.144 m | 1.37 s | 43.9 ft/s | 30 mph |
| 40 ft | 12.19 m | 1.58 s | 50.7 ft/s | 34.6 mph |
| 50 ft | 15.24 m | 1.76 s | 56.7 ft/s | 38.7 mph |
| 75 ft | 22.86 m | 2.16 s | 69.5 ft/s | 47.4 mph |
| 100 ft | 30.48 m | 2.49 s | 80.2 ft/s | 54.7 mph |
| 200 ft | 60.96 m | 3.53 s | 113 ft/s | 77.3 mph |
| 500 ft | 152.4 m | 5.58 s | 179 ft/s | 122 mph |
| 1000 ft | 304.8 m | 7.88 s | 254 ft/s | 173 mph |
How long does it take to fall? (metres)
| Drop height | Feet | Fall time | Impact speed | Impact speed |
|---|---|---|---|---|
| 1 m | 3.281 ft | 0.452 s | 4.43 m/s | 15.9 km/h |
| 2 m | 6.562 ft | 0.639 s | 6.26 m/s | 22.5 km/h |
| 3 m | 9.843 ft | 0.782 s | 7.67 m/s | 27.6 km/h |
| 5 m | 16.4 ft | 1.01 s | 9.9 m/s | 35.7 km/h |
| 10 m | 32.81 ft | 1.43 s | 14 m/s | 50.4 km/h |
| 15 m | 49.21 ft | 1.75 s | 17.2 m/s | 61.7 km/h |
| 20 m | 65.62 ft | 2.02 s | 19.8 m/s | 71.3 km/h |
| 30 m | 98.43 ft | 2.47 s | 24.3 m/s | 87.3 km/h |
| 50 m | 164 ft | 3.19 s | 31.3 m/s | 113 km/h |
| 100 m | 328.1 ft | 4.52 s | 44.3 m/s | 159 km/h |
| 200 m | 656.2 ft | 6.39 s | 62.6 m/s | 225 km/h |
| 500 m | 1 640 ft | 10.1 s | 99 m/s | 357 km/h |
The longest drops in these tables are where air resistance starts to matter — see the caveat below.
How long is the fall from a familiar height?
The same arithmetic against heights people actually recognise. Storeys assume a 3 m floor-to-floor, which is typical for housing — commercial floors are often taller, so treat a storey count as approximate. Diving figures are the real competition platform heights.
| Height | Metres | Feet | Fall time | Impact speed | mph |
|---|---|---|---|---|---|
| Table top | 0.75 m | 2.461 ft | 0.391 s | 3.84 m/s | 8.58 |
| 1 m springboard | 1 m | 3.281 ft | 0.452 s | 4.43 m/s | 9.91 |
| 3 m springboard | 3 m | 9.843 ft | 0.782 s | 7.67 m/s | 17.2 |
| One storey | 3 m | 9.843 ft | 0.782 s | 7.67 m/s | 17.2 |
| 5 m platform | 5 m | 16.4 ft | 1.01 s | 9.9 m/s | 22.2 |
| 7.5 m platform | 7.5 m | 24.61 ft | 1.24 s | 12.1 m/s | 27.1 |
| Two storeys | 6 m | 19.69 ft | 1.11 s | 10.8 m/s | 24.3 |
| 10 m Olympic platform | 10 m | 32.81 ft | 1.43 s | 14 m/s | 31.3 |
| Three storeys | 9 m | 29.53 ft | 1.35 s | 13.3 m/s | 29.7 |
| Five storeys | 15 m | 49.21 ft | 1.75 s | 17.2 m/s | 38.4 |
| Ten storeys | 30 m | 98.43 ft | 2.47 s | 24.3 m/s | 54.3 |
| Twenty storeys | 60 m | 196.9 ft | 3.5 s | 34.3 m/s | 76.7 |
A ten-metre platform gives a diver about 1.43 seconds in the air — which is the whole budget for a dive with three somersaults in it.
The same drop on other worlds
Fall time in seconds, for the four gravities in the picker above. Weaker gravity means a longer, gentler fall: the Moon takes almost two and a half times as long as Earth for the same height, which is why the Apollo footage looks slowed down when it isn't.
| Drop height | Earth (9.80665 m/s²) | Moon (1.625 m/s²) | Mars (3.721 m/s²) | Jupiter (24.79 m/s²) |
|---|---|---|---|---|
| 1 m | 0.452 s | 1.11 s | 0.733 s | 0.284 s |
| 3 m | 0.782 s | 1.92 s | 1.27 s | 0.492 s |
| 10 m | 1.43 s | 3.51 s | 2.32 s | 0.898 s |
| 30 m | 2.47 s | 6.08 s | 4.02 s | 1.56 s |
| 100 m | 4.52 s | 11.1 s | 7.33 s | 2.84 s |
Free fall
An object dropped from rest accelerates downwards at a steady rate — on Earth about 9.807 m/s² — so its speed grows in proportion to time and the distance it has fallen grows with time squared.
h = ½ g t² · v = g t · t = √(2h / g)
Give this calculator either a drop height or a fall time and it works out the rest, including the impact speed. Heights can be entered in metres or feet, with the results shown in m/s and km/h or in ft/s and mph to match. You can also switch gravity to the Moon, Mars, or Jupiter to see how much the same drop changes elsewhere.
Mass doesn't matter
Notice there's no mass in any of these formulas. In the absence of air, a feather and a hammer fall identically — famously demonstrated on the Moon during Apollo 15. Heavier objects are pulled harder but are also harder to accelerate, and the two effects cancel exactly.
Worked example
Drop something from 10 m: the fall takes √(2 × 10 / 9.807) ≈ 1.43 s and it lands at 9.807 × 1.43 ≈ 14 m/s, about 50 km/h. Double the height to 20 m and the time only rises to about 2.02 s — because distance goes with t², halving the height doesn't halve the time.
Why the time grows so slowly
That square root is why the tables above look lopsided. Going from 10 ft to 100 ft is ten times the height but only about three times the fall time. Todouble the time you have to quadruple the drop. Impact speed, by contrast, rises in step with time — so extra height mostly buys speed rather than seconds.
The air-resistance caveat
These equations ignore drag, so they're accurate for dense objects over short drops and increasingly wrong for long ones. Real falling bodies approach aterminal velocity where drag balances gravity — roughly 200 km/h (125 mph) for a skydiver in a belly-down position — and never exceed it, no matter how far they fall. Treat the 500 ft and 1000 ft rows as an upper bound on speed rather than a prediction.
Common questions
- How long does it take to fall 100 feet?
- About 2.49 seconds, hitting roughly 54 mph. The relationship is t = √(2h/g), so it is not proportional to height — 200 ft takes 3.53 s rather than 5 s, because the object is travelling faster the whole way down. The tables above list the common heights directly.
- Does a heavier object fall faster?
- Not in a vacuum, no — and that is the striking thing about these equations. Mass does not appear anywhere in them, so a feather and a hammer dropped together land together, as was famously demonstrated on the Moon during Apollo 15. Heavier objects are pulled harder, but they are also harder to accelerate, and the two effects cancel exactly. Add air and it stops being true: see terminal velocity.
- At what height do these numbers stop being accurate?
- There is no sharp cutoff, but the error grows with speed because drag rises with velocity squared. For a dense compact object the figures are good for the first few seconds — say up to 50 m or so. Beyond that the real fall is slower than predicted, and for anything light or large the calculation is optimistic almost immediately. The 500 ft and 1000 ft rows should be read as an upper bound on speed, not a prediction.
- Why does the Moon give a longer fall time?
- Because its surface gravity is about a sixth of Earth's, and fall time scales with 1/√g. A sixth of the gravity means √6 ≈ 2.45 times the fall time, which is exactly the ratio in the table above. It is also why Apollo footage looks like slow motion when it is running at normal speed — everything really is falling two and a half times slower.