Suicide Jumping: What's the minimum height?

General rule of thumb is 50% of all falls that are from three times your height are fatal. In other words, a six foot individual will die 50% of the time from an 18 foot fall, while an infant two feet tall will die 50% of the time from a six foot fall. So a fall from five stories is probably going to be fatal.

One thing to remember here is that there is a noticeable height different between jumping from the fifth story or from the roof of a five story building. Jumping from the fifth story is closer to jumping from the roof of a four story building. Five stories is approximately 60 to 75 feet in height (12 - 15 feet per story).

Best of luck,

Jim Clark-Dawe

IIRC, the kill point for landing in water is about 130 feet. Maybe you could have the character jump a distance that would kill him landing on concrete, but accidentally land in a pool instead...

There have been many instances where a person fell, jumped or was pushed from a height that would have killed them except they landed on an awning, some bushes, a tree, some soft dirt, in a dumpster,etc

Kathie Freeman said:

There have been many instances where a person fell, jumped or was pushed from a height that would have killed them except they landed on an awning, some bushes, a tree, some soft dirt, in a dumpster,etc

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Are you an EMT? A member of an emergency response squad? Or did you see these "many instances" on television? No, wait! You live in Fallbrook. Never mind.

5 stories sounds good to me (as just a reader). Maybe 4? It depends on the explanation at those heights, but sure.

Someone could die from falling over, but I think that three times one's height rule is about right. With that and the character's survival in mind, I think that two stories would work, and anything over three stories would be too likely to kill.

There is no height of assured death only a higher probability. People have survived amazing falls even out of planes when the parachute fails (google it). Yes, it is a miracle, but it can happen.

I would read up on these amazing survival stories to find out why they survived it.

I would question whether someone really wanted to commit suicide if he/she jumped off of a two or even three story house. Five stories works for me.

I knew someone who jumped off the Key Bridge in Washington D.C., hit the water of the Potomic, came up and swam to shore with just a few bruises and a cracked rib. It's at just under 100 feet above the river.

RainyDayNinja said:

IIRC, the kill point for landing in water is about 130 feet. Maybe you could have the character jump a distance that would kill him landing on concrete, but accidentally land in a pool instead...

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If you aren't diving properly water can be worse than concrete at just 30 feet.

Amazing stories of toddlers falling four or five stories and surviving. Much depends on the nature of the landing surface, and the bodies disposition when it hits. A six foot fall onto your head off a ladder can break your neck and kill you. Twenty foot fall into a freshly turned flower bed - landing feet first (assuming a young healthy athletic victim) - would break some bones, but you could reasonably survive.

I read this in a physics book, so it must be true. Imagine the following animals, dropped down a mineshaft;
a) A mouse. It will hit the ground and immediately scurry off. Probably feeling slightly perturbed.
b) A cat. It will be stunned but unharmed.
c) A human. Bones will break, prognosis not good, but if you don't land on your head/spine you might survive.
d) A horse. It will splash.

You need to take weight into account as well as height. F=MA and all that.

I started to make a comment, but it didn't make sense, so I gave up.

But as others have said, the degree of injury depends a lot on how you land.

I watched a guy (elopee from the psych ward) jump off the roof of a 6 story hospital. He landed on grass, bounced about 8 feet and was quite dead. Further investigation found that he thought he could fly.

Chase said:

Are you an EMT? A member of an emergency response squad? Or did you see these "many instances" on television? No, wait! You live in Fallbrook. Never mind.

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Good one, never thought of that. No, I just read the papers, watch news on TV. The most remarkable one that comes to mind was a skydiver whose chute didn't open, landed in mud, was seriously injured but recovered.

weight does NOT factor into it. Everything falls at the same rate, regardless of weight. Thirty two feet per second, per second.

AIR RESISTANCE does factor into it. This is why a parachute will slow you down. This is why a skydiver that is 'higher' than one that is 'lower' can catch up, by pulling his arms in and tucking his head into a 'dive'. The profile presented to air resistance will determine terminal velocity. Every falling body has one. (MASS is not the same as WEIGHT so think in terms of mass and surface area.)

Aschenbach said:

I read this in a physics book, so it must be true. Imagine the following animals, dropped down a mineshaft;
a) A mouse. It will hit the ground and immediately scurry off. Probably feeling slightly perturbed.
b) A cat. It will be stunned but unharmed.
c) A human. Bones will break, prognosis not good, but if you don't land on your head/spine you might survive.
d) A horse. It will splash.

You need to take weight into account as well as height. F=MA and all that.

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depending upon the depth of the mineshaft.

Second the notion: Weight does not factor into the SPEED of the fall, only the final MOMENTUM of the object. Minus air resistance, of course. Galileo, Tower of Pisa, cannonballs and such.

Now, living close to NYC, there are stories about once a month of someone taking the exterior express. Sometimes a kid falling out a window (tragic), last month a robber looping over the handrail of the fire escape (comic) Most die, but what makes the tabloid front page are the ones that live. And most of those land on something energy absorbant (dumpster, awning, car roof) A 4-5 story fall and living is believable, but unlikely. Have him land on a car roof if you want him to live.

Just for the fun of it, I generated this table, based on 32.174ft/sec for 1g, speed=acceleration x time, and distance=.5 x acceleration x time[SUP]2[/SUP]. A residential story is about 12 feet tall, a office building could be 14 feet.

Time Speed Distance | Stories Distance Time Speed
0 0 0 | 0 0 0.0 0
1 32 16 | 1 12 0.9 28
2 64 64 | 2 24 1.2 39
3 97 145 | 3 36 1.5 48
4 129 257 | 4 48 1.7 56
5 161 402 | 5 60 1.9 62
6 193 579 | 6 72 2.1 68
7 225 788 | 7 84 2.3 74
8 257 1030 | 8 96 2.4 79
9 290 1303 | 9 108 2.6 83
10 322 1609 | 10 120 2.7 88
11 354 1947 | 11 132 2.9 92
12 386 2317 | 12 144 3.0 96

So, your Darwin Award guy flying off the fifth story is going to be airborne just shy of two seconds, and hit at 60 mph. He MIGHT survive.

ps - no, I don't know how to make the freaking table come out right. (*(^^&%&^* editor removes all the nice extra spaces I stuck in there. Sheesh.

This was a really interesting question. I loved reading through the answers, needed this question to validate my second books facts Thanks!

Knew a guy in high school who climbed a water tower and fell off. He wasn't intending to jump, just that he was an idiot and really drunk. He was pretty screwed up and in the hospital for months, but lived. Supposedly the doctors said it was because he was so drunk his body was relaxed when he hit the ground.

Certainty

So I guess the 16th floor of an apartment is a good bet.

This thread is eighteen months old, FYI.

It all depends on what they are landing on. There have a been a very very small number of cases where someone goes parachuting and the chute doesn't open and they survive the fall. Also if you fall from 20 feet it can completely shatter your heels. If you jump head first it is going to take a shorter distance. I would say something like three feet would sound better. That is just my opinion. You can always talk about how it looks really high to him or something, but once he jumps it is not as far as he thought. That is my two cents.

Parametric said:

This thread is eighteen months old, FYI.

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Yes it is, and I'm locking it until & unless anyone PMs me with a good reason to keep it open.