Why Falling Damage Is Unrealistic

Posted: 19 July 2012 in House Rules
Tags: , , , ,

Thanks to a post by Shortymonster I stumbled over to the Large Polyhedron Collider (A+ on the blog name), where he’s got a post about the Realities of Falling.  He sets out a few milestones: serious injuries occur from falling 25-30ft onto a hard surface, and death is very likely from a fall of 50-60 feet (onto a hard surface).  He goes on to talk about falling into soft surfaces (like deep water, or snow), and the differences landing orientation makes, and the kind of damage you can expect to do if you land on crates or a car or another person.

Because of this, I think we need to change the way falling damage is handled in D&D: as it is, it’s just too lethal to be realistic.That last line probably sounds like blasphemy to a lot of you, and it should.  In all the discussions I’ve seen about hit points and D&D, falling damage is probably the most-cited case for why D&D hit points don’t make sense.  “PCs can fall off a tower and, at worst, be mildly inconvenienced.” The issue of falling damage not meaning anything comes from the fact that people measure the game from the perspective of PCs, and expect to calibrate the world based on what a PC is capable of, but this fails to recognize (1) that PCs aren’t regular people, and (2) regular people rarely make 2nd Level, let alone 8th or 12th. A 12th Level PC can be expected to have on the order of 54hp (depending on class, etc) and so could walk away from a 200ft fall — but a 12th Level PC is also on par with Hercules, killing Hydra and Dragons.

Here’s my thinking, based on some assumptions that I feel are inherent to 3.5.

The typical person in 3.5 is a 1st Level Commoner, giving them an average of 3hp, 6hp on the high end. A battle-trained warrior will have 5hp, 10hp on the high end. A person will have plus or minus 1hp if they’re particularly tough or fragile. An exceptionally tough, battle-trained guy might have as much as 15hp. By 3.5 rules, a creature takes 1d6 damage per 10 feet fallen, to a maximum of 20d6 at 200ft or above. Minimum damage is 1 (up to 20 at 200ft), average or expected damage is 3 (up to 70 at 200 ft), and maximum damage is 6 (up to 120 at 200ft). A typical (3hp) person is expected to be at 0 hp after a 10ft fall; a creature at 0 hit points is considered dieing and probably only has a few minutes to live, unaided. Even if you assume a roll of 6 indicates landing on your head, this feels extreme.

A creature can reach a negative score equal to their CON score (10 for regular people) before they are simply dead (no chance for medical aid). For a regular person, that means that 13 damage is absolutely fatal; that’s almost possible on a 20ft fall (12 max), is expected at about a 40ft fall (14 expected), and is guaranteed at a 130ft fall (13 minimum).

If we demote falling damage to d4s, the numbers become: Minimum damage 1 to 20, expected damage 2 to 50, and maximum damage 4 to 80. A regular person is expected to take severe injury from a 10ft fall but probably won’t die; they could die absolutely from about a 30ft fall (12 max), will likely die from a 60ft fall (15 expected), and will die from a 130ft fall (13 minimum).

Because a 10ft fall is still likely to cause a lot of injury to a regular person, and is about 50% likely to leave them dieing at 0hp, I still feel like this is a bit harsh, but we quickly run out of smaller die sizes to use.  The ever-popular d3 might be a better fit (min 1-20, expected 2-40, max 3-60; possible death at 50ft, expected death at 70ft, assured death at 130ft), but I’m not really a fan of it myself. A 33% chance of 0hp from  10ft fall at least feels more realistic.

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Comments
  1. While I don’t agree with wanting to tone down falling damage in D&D (I outlined the reasoning in my reply to your comment on my post), I don’t think that d4 is still too harsh. One of the most important things to remember is that the orientation of the fall is the most important factor. Since that’s abstracted in the damage roll, and there are rules to mitigate the damage (intentional jumps, Jump or Tumble skill check), you can view unmitigated falling damage as the worst possible situation to fall in (and likely to hit your head, unless you get lucky, which would be a low damage roll).

    • Jack says:

      And this is all true — if I didn’t stake it directly in the article, I agree that a high damage roll indicates a bad landing position (thus freeing me from having to care about position overly much). However, if 3 damage puts a character at 0-and-dying, that means that a d4 has a 50% chance of “you land on your head,” and that just feels wrong.

      As far as mitigation, the only skill check listed is “DC 15 to ignore 10ft of a fall”, which means no damage from a 10ft fall. Our NPC-of-measure has a +0 on such a check, so they only have a 20% chance of success; you’re still looking at a 40% chance of “fall on your head and die.” Real-life falling just doesn’t seem to have that level of lethality.

      Can we complain that the system doesn’t have rules for “fall poorly and break your arm”? Sure, that’s exactly the sort of hole I’m hoping to fill with this blog. But that question isn’t answered either way by establishing what actual-numbers for the falling mechanics do say.

      • It’s not really 50% to land on your head, just 50% that you land in a way such that your head hits hard. Since falls aren’t intentional, landing in a way that your head hits is likely. As far as not liking the odds, there’s only so much granularity you can have when calibrating on a 4hp standard.

        • Jack says:

          Yeah, a good point. As far as 4hp goes, that’s part of a larger point: D&D does not model minor wounds well. At least, I think so. Tackling that issue is next on my plate, I guess, once Life gives me some breathing room.

  2. After the first few levels, the way HP scales, any resemblence of realism is out the door, which is one reason this type of gaming system generally isn’t for me. In my mind, the DND system is in place for characters to do cool things and they are on a path to become super heroes but set in a fantasy setting….and it takes a might big fall to kill Captain America. Why worry about the realism of a 30 ft fall for a high level characters when they can handle hordes of giants in hand to hand without even breaking a sweat?

    • Jack says:

      “Why worry about the realism of a 30 ft fall for a high level characters”

      Because the game is based on taking on the role of a character and making decisions as though you were that character. In order to do so we need to be able to reason the way the character would, and the more information we can have about the world the easier it is to do that. This is precisely why we don’t want to calibrate to PC-quality (or high-level) characters; if we’re modeling their world on ours we need to compare it to people like those that exist in our world, and Captain America does not actually exist (and even if he were, he’s not representative). Just because Captain America doesn’t exist in our world, though, doesn’t mean it’s impossible or absurd to try to realistically portray what a guy with the strength of 10 men would be capable of doing if he DID exist; that’s kind of the whole point of the exercise of role-playing.

      • Thanks for your response….I think understand your postion a bit better and it did cause me to look at some physics on falling…

        The only thing I would add is that if you are concerned about being realistic, damage should not be on a linear progression since damage will be based on squaring the value of velocity and a character would be accerating until reaching terminal velocity.

        • Jack says:

          As I may have noted elsewhere (but maybe I haven’t; that needs to be remedied), I think that hit points, damage, and healing are probably the weakest parts of the D&D 3.X system. I’ve heard it said that HP works the way it does solely because Gygax wanted combat to play out a certain way. At the very least, I think Hit Points represent something other than what most people expect, and that’s problematic. Some day I hope to form a full post (or three) on the issues.

          That being said, F may equal MA but (1) we shouldn’t need advanced math or physics degrees to play the game; in other words, it only needs to be “good enough for fantasy,” and (2) until we know what HP and damage represent we can’t really say whether extra dice are added linearly or quadratically; I suspect it doesn’t matter for the most part, as long as “likelihood of death” is modeled appropriately. Terminal velocity is one argument for why falling from 300ft is the same amount of dice as 200ft, though (but I remember seeing somewhere that you need to fall over 1200ft before terminal velocity becomes a factor, so…).

          • The Internet is making me want to argue….. 🙂 Time to get off that wagon.

            Fair enough, I see where are going with this….but I will throw in a couple thoughts that came to me. (take it for what it is worth for a non- DnD Player).

            For a more “realistic” approach…perhaps if one is falling on “soft” ground…or perhaps with cover….allow additional saving throws to halve damage for each success, (or perhaps mitgate most damage if a threshold number of rolls are successful). That could represent somebody getting very, very lucky as does happen from time to time in real life.

            I do also think varying the die used bases on what you are fallin on could be interesting…
            d6 for hard ground….d10 for rocky….d4 for soft etc…..

            • Jack says:

              Heh, I’m always up for “lively discussion.”

              Good ideas all around, and I’m definitely in favor (generally) on taking conditions into consideration, such as soft ground etc.

              That being said, I’m not sure that HP is really granular enough to allow for the kind of variation you want to see. If 3 damage is enough to effectively kill someone and 13 damage is instadeath, you’re looking at 66% lethality for d6, 80% lethality for d10, and 50% lethality for d4. As The Doctor noted above, this breaks down a little bit if you looked at the battle-hardened tough guy compared to the average joe, and maybe some terrain would have an 80% lethality at 10ft (though I doubt it); but I don’t have a strong enough handle on hit points to really say.

        • Terminal velocity doesn’t come into play, for a variety of reasons. From a strictly physics standpoint, a body in free fall quickly approaches terminal velocity – the rate of acceleration slows dramatically due to the force of air resistance increasing so quickly, so a linear increase to a maximum value is a useful simplification. Aside from which, the distance required to reach terminal velocity is an order of magnitude beyond what an RPG tends to model (and what D&D specifically models).

          • At the risk of talking beyond my intellegence…….

            I think the air resistance would have effect as you got closer to terminal velocity, and much less effect during the first portion. Thus intially there would be a dramatic increase in deadliness and then a slowing down after some critical point.

            People die from falling 5 feet. People survive falling out of airplanes. If you are wanting to model this somewhat “realistically” I do not think such is possible in DnD, (or perhaps most other games) using a 1dx per 10′ model. The nice thing about 1dx/y feet is that it “feels” right and is simple to calculate….but it isn’t realistic. But the question is how much realism do we really want in our games?

            • Jack says:

              “But the question is how much realism do we really want in our games?”

              Which is kind of my point. You’re right about wind resistance, dying from a bad 5′ fall, and surviving stupid-high drops. In general, I aim for “realistic enough for fantasy,” where it’s quick and relatively intuitive and generally models *most* situations well. I actually like the sort of “chance on a d6” system Brendan mentions, or Save Vs Death for extreme falls. They can all be useful tools, seasoned to taste.

      • André Rodrigues says:

        Although the Kinetic Energy is proportional to Velocity squared, you only get geometric growth if you plot it against time.

        If you plot it against distance, it is linear (if we disregard the air resistance).

        Here’s the math:

        v = g*t; (v = velocity, g = 9.81 m/s^2 and t = time falling)
        Ek = 1/2*m*v^2 = 1/2*m*g^2*t^2 (Ek = kinetic energy, m = mass of the person falling)
        x = 1/2*g*t^2 (x = distance fallen)

        Ek/x = (1/2*m*g^2*t^2)/(1/2*g*t^2) = m*g Ek = m*g*x

        That means that the energy of the fall in proportional to the height fallen.

        If you factor in the air resistance (I did a numerical simulation, so I have no formulas), the energy increases less as the distance fallen increases (as you said in a later post), but it’s almost unnoticeable for heights up to 100 feet.

        I totally agree with the idea that heroes in D&D 3.x above a certain level are essentially demigods. The problem is that the books as written don’t quite frame them as such: in a way they are akin to super-heroes, but they are still looked upon as mortals, and since the threats always escalate with them, the threat of death may actually increase as you get to the higher levels.

  3. Brendan says:

    In OD&D, you only take damage when falling into a 10′ pit in a roll of 2 in 6 (33%), and if you do take damage it is one die of damage per 10′. That seems pretty reasonable to me. My house rule is that past 50′, it turns from damage to a saving throw against death. That seems to fit the crazy luck required to fall from very great heights, and also works well in the context of the game. I prefer this to the 3E massive damage (which encourages calculationism on the part of players) or the earlier system shock roll (which is an unnecessary additional system and though I’m not sure anyone has advocated using it for falling damage, it would be a natural fit).

    • Brendan says:

      To further clarify my intent, I think falling from a great height should always be scary to players, even if there is a chance of survival. Allowing players to count HP and distances robs the experience of its visceral nature, which destroys the power of what should be a potent threat. That is what is required for “taking on the role of a character and making decisions as though you were that character” in my opinion.

      • Jack says:

        I generally agree — certainly, falling should always be a concern in games I run, because I run low-level, high-lethality games.

        I’m not sure it should *always* be a concern in every situation: Superman hardly ever cares about slamming into concrete at terminal velocity, and if we’re playing a game at that level of power it makes sense to follow suit. (I think the extreme end of D&D is essentially playing Superman, Hercules, and other near-gods.)

        Because of that, a system of massive damage works because near-gods can sustain those high levels of punishment. You could tweak the Save Vs Death idea or other systems for a similar result, but the damage vs hit points works out-of-the-box.

        • I think the idea that higher-level characters in D&D are akin to demigods is one that makes the system make more sense (and actually makes me want to look at 3e again), but I don’t think that’s the intent of D&D. Heroes go on adventures, gain experience, skills, abilities, and treasure, but they’re still essentially human (elf, dwarf, or whatever). The idea that an exceptional person can gain experience and thereby become the equivalent of a demigod or superhero is not a basic assumption when it comes to D&D, which leads to a lot of complaints about realism. I think that’s a pretty fundamental difference in assumptions, and needs to be explicitly cleared up straight away in these types of discussions.

          • Brendan says:

            Dr. Gentleman wrote: I think the idea that higher-level characters in D&D are akin to demigods is one that makes the system make more sense

            I agree this is interesting, but I’m not convinced that Justin Alexander did not invent the idea himself. The old BECMI D&D supported the idea of attaining immortality around 36th level, but I haven’t been able to find much mention of this in the 3E core books. Even the Epic Level Handbook, which supposedly takes characters from 21st to 30th level (IIRC), does not seem to support demigod level play, though admittedly I haven’t looked at it carefully.

            That’s not to say that it can’t be used in that way, it just seems like a stretch to say that it was intended to be played that way.

  4. […] Why Falling Damage Is Unrealistic […]

  5. Anonymous says:

    Had a player use the dig spell under a chimera skeleton. 2 tons of beast fell 20ft. Under the standard rules that should have killed it. But I only ruled 5d6 for damage.

    • Jack says:

      I think you may have that backwards – a creature that falls takes 1d6 per 10ft drop, so a creature that falls 20ft takes 2d6 damage (2-12, with 7 being expected; odds are, this would kill most normal people most of the time). Weight only comes into play when a falling object hits a target – in this case, the damage the floor of the pit takes when the chimera lands. In that case, an objects deals a target (weight/200)d6 damage, plus d6 for each 10ft after the first that the object falls. So the pit floor takes 11d6 damage, but there’s probably no reason to track that.

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