Falls are a decently common danger in many adventure locales, but how reasonable are they really compared to reality? Is it the OD&D “a 5-foot fall kills the average man” or the 5e “a 10th (or 5th level if they are angry) level barbarian can fall literally any distance and always be safe “. So… what’s reasonable here?
Things About Falls
Falling long distances is dangerous, obviously. But how dangerous? Well, that obviously varies a lot, but from what I’ve read (this one’s pretty good), a fall starts getting dangerous at around 6-7 meters (20-25 ft.) and get really dangerous at 12 meters (40 ft.), topping out at a near 100% mortality rate at around 28 meters (90 ft.). So… what to make of this? First of all, you’ve got to note down how much survivability your characters have. This should be used as a basis for how much damage different falls should do (you can’t design a damage system without knowing how much HP people will have).
- 15 meters (50 ft.) is 50% mortality.
- 25 meters (80 ft.) is 90% mortality.
- 28 meters (90 ft.) is ~100% mortality.
- 5-6 meters and above may lead to serious injuries on a hard landing.
- < 7 meters on a hard landing is more likely not to kill than to do.
- > 12 meters on a hard landing is more likely to kill than not.
It seems a hard landing is around +50% damage.
Luckily, fall injuries are best based on kinetic energy, which scales linearly with fall height (it’s based on the square of the speed, which is based on the root of the height… You can use energy = mass × gravitational acceleration × height if you need it).
But back to toughness things:
If you use regular old linear HP, fall damage is going to break so fast. Most likely, a badass war veteran (say a 4th level fighter with 35 HP depending on edition) won’t survive a 40 meter fall that much more than a random person off the street (0th level, 4 HP in many editions). But with 1d6 per 10 ft, the random person will die at nearly one-tenth the distance. You get the idea.
So… either you have near-static HP over levels, accept that falls are incredibly inbalanced, or use percentage damage… I guess.
In my case, a normal commoner might have 15 HP, and is able to survive 10 points of injury in the moment. Including some other rules, an average person might be assumed to survive up to 15 points of damage in one if they had full HP (which actually ends up being equal to their max HP… huh).
This is compared to the corresponding number for a stronger individual’s 20-something, and 25 for a really tough one. This might go all the way up to 35 for some crazy tough mythic hero with maximized stats.
Through MATH, the commoner has a 51% chance of death when taking 7d6 damage for 15 meters. Yes, the toughie will have a 84% survival rate, but that’s ok. It’s not 100%. And at 25 meters the commoner is basically 100% dead, the toughie 95% dead, and the literal demigod still has a 10% chance of dying. Seems… passable.
(While there’s a big difference between 40 and 15 HP, it’s only around two and a half times. It’s not as bad as linear HP. Which is really what messes up most fall damage systems.)
This post took far too long to write… I hope its useful to someone.