2023-07-31

How Much Weight Can a Horse Carry in D&D?

Young horse with luggage
I've vaguely known for a long time that there was some essential problem with the system for horse encumbrance in early D&D (O/AD&D). But I hadn't personally done the accounting to pinpoint where the issue was; I recently went on a deep dive on that point. Big thanks to the folks on the Wandering DMs Discord server for pointing out the problem in OED and helping me think through this reasonably.

Original D&D

Original D&D encumbrance rules
To the side here is the page of encumbrance rules from OD&D (Vol-1, p. 15). Once again I'm struck by the overall completeness of the Original Dungeons & Dragons rules: whatever its other faults, everything you could possibly need to know about D&D encumbrance is included on this one digest-sized page. This includes: the weight of weapons and armor, helmets and shields, bows and arrows, miscellaneous gear, coins of any type, gems and jewelry, magical treasures, movement categories, container carrying capacities, saddles and barding for horses, and the weight of an average man. Plus a complete example. This compares extremely favorably to what came later: in AD&D, you'd need to look in at least four separate books, published over eight years time, to put all the equivalent information back together. (This complication makes it nontrivial to do the desired accounting as I wanted for AD&D, below).

So, here's the accounting for light, medium, and heavy lancer cavalry, under reasonable assumptions, according to the OD&D rules.

OD&D Cavalry Weight Accounting

Here's some notes & observations on that.

  • Horses are only given a single maximum load limit (in the Vol-2 monster entry): by type, 3000, 3750, and 4500 coins. These values are vaguely reasonable: real-world research frequently pegs 30% body weight as the point where horse gait performance starts to experimentally drop off (e.g., Wikipedia: "horses can carry approximately 30% of their weight"). If we take very round estimates for horse weight of 1000-1250-1500 pounds, and compute 30% of those, then we get exactly the load limits shown here.
  • The weight of men given, 175 pounds, is roughly equal to the average weight of men in the U.S. in the era of publication (173.4 pounds, per NHANES I, 1971-74 from the CDC; compare to S&P's estimate for medieval Swiss men, 71.7 kg = 158.1 pounds).
  • The weights for arms & armor seem high, like, around double the weights based on real-world examples (possibly more on that later). 
  • These rules only give one type each for a saddle, barding, shield, helmet, lance, and one-handed sword, so these are common across each cavalry type.
  • Following the listing for bandit men et. al. (in Vol-2), the expectation is that heavy horse are barded, but light and medium horse are not.
  • In particular, the barding weight (75 pounds) is reasonable; compare to Wikipedia ("barding, or horse armour, rarely weighed more than 70 pounds"). Several examples at the Met Museum weigh in at around 90 pounds. 

Conclusions for OD&D:

  • The fully kitted-out cavalryman weighs in nicely within the load limit given for each type of horse (indicated by green highlight in table).
  • Moreover, the gear for each type is greater than or equal to the limit for the next lower type -- implying that for medium kit-out you want the medium horse, and for heavy kit-out you really need the heavy horse. (Arguably, you could just barely use a light horse for medium kit; but let's ignore that wrinkle for now.)
  • In addition, if we look at the gear on the man alone (perhaps if they have to fight on foot), these weights also synch up perfectly with the encumbrance tiers for men (given as 750-1000-1500 coins). Respectively, each is just barely within the window for light, medium, and heavy loads for men (12-9-6 inch movement tiers).
  • Overall -- this is excellent, coherent game system design. All the parts work together to generate the expected & desired results. The numbers are within the ballpark of modern real-world research. It has the sign of someone who paid close attention to both historical details and good wargame design.

Advanced D&D

Now for a different story. First of all, doing a similar accounting for AD&D is a lot more work, because (as noted above), the equivalent information is spread all over at least four different books. To wit:
  • The PHB (1977) has melee weapon weights (p. 37), and elsewhere movement thresholds for men (p. 101).
  • The DMG (1979) has armor & shield weights (p. 27), and in Appendix O (p. 225), most other weights for miscellaneous gear, bows & arrows, helmets, saddles, etc.
  • Container carrying capacities could only be found if you looked in the AD&D Player Character Record Sheets product (1980). 
  • The specifications for barding weren't given until an article by Gygax in Dragon Magazine #74 (1983), and then reprinted in Unearthed Arcana (1985).

You can take this as a case study of my thesis that there was a lot of key stuff in OD&D that was haphazardly copied or lost in the transition to AD&D, making it a lot more cryptic and mysterious than it needed to be. Anyway, putting it all together we can get the accounting for cavalry weights in AD&D:

AD&D: Cavalry Weight Accounting

 Observations here:

  • In the AD&D Monster Manual, horses get two load categories: light (full-speed; approximately equal to the OD&D limits), and heavy (half-speed; about double the light load). That's arguably reasonable.
  • The average male human weight of 175 pounds is reiterated in the table on DMG p. 102, so we use that again in our spreadsheet.
  • The weight for arms & armor are generally reduced, pulling them more towards real-world scales, as far as I can tell.
  • The Advanced D&D ruleset gives distinctions to different types of saddles, barding, shields, helmets, lances, and swords -- so I've indicated the expected selection for each.
  • In particular, DMG p. 31 describes medium horsemen as "similar to heavy cavalry", so when necessary I picked the heavier version of the gear (saddle, shield, helmet).
  • The AD&D Monster Manual makes no reference to expected barding anywhere in the book (contrast with OD&D above). So are we to assume that light cavalry always use the leather barding, medium chain, and heavy plate, as provided in the equipment list? That would be my best guess of the intent (despite it being ahistorical to my knowledge) -- so that's what I've entered for each type.
  • Strangely, Gygax has massively increased the weight of barding to a completely ludicrous level (noted by orange warning lights above). Even the leather barding is more than double the weight of barding in OD&D. Plate barding is more than quintuple the heaviest historical example I could find -- on its own, maxing out the first-tier load limit of the heavy horse. (!)

Conclusions for AD&D:

  • The fully-kitted cavalrymen are all significantly over the limit for expected full-speed horse movement. In particular, the heavy horseman is far over the maximum limit for the heavy horse, and cannot move at all by the letter of these rules. The medium horseman is only 3 pounds away from the same thing. (Noted by yellow & red highlights.)
  • Apart from the barding issue, looking at the men alone (i.e., off the horse), there is a similar problem. The load limits for average-strength men have been reduced by an order of about a half (35-70-105 pounds in the PHB), and the light & medium men are over the expected limits for the first two categories. (Despite this reduction being maybe real-world reasonable, it outpaced the reduction in arms & armor weight to drop the men into slower categories.)
  • Overall -- this design is simply broken. The primary problem is the unwarranted and inexplicable inflation in barding weights (which, again, renders the heavy horseman immobilized). But more generally, the fragmentation of where the encumbrance rules are located (scattered all over many books) is echoed in the design decisions being unsynchronized, and have produced a fundamentally incoherent system.

Further Discussion

Obviously, this is another instance where the Original D&D system runs the table on the later Advanced D&D system. It's really puzzling how the latter system was allowed to get so fragmented, so quickly, as to produce results like this.

I suppose one could argue that the light and medium horse types shouldn't be expected to wear barding -- despite a move-limit table in Dragon #74/Unearthed Arcana showing them in it (a table which doesn't make any sense, because the raw weight has already slowed the horse down more that the table shows for armor max moves). At the very least, you have to observe that plate barding is useless, because it and a heavy horseman are more than any horse can bear.

Of course, a lot of people don't want to use encumbrance rules at all. If you've read this blog before you're likely aware of my argument that scaling the weight units to individual coins was too fine-grained, and juggling all the big numbers is a major part of the headache. So I prefer using a bigger unit like historical stone weights, which (usually) makes the calculations easier to estimate and add up.

Based on our research on real-world horse carrying capacity, I'm confident that the 30% body weight number is a solid value to use before horse speed drops off (see short bibliography below). And aligned with patron feedback, I've become convinced that the 20% body weight number cited in a lot of modern horse-riding articles represents a very conservative rule-of-thumb, trying to be painstakingly humane, with a large safety buffer built in (i.e., not representing medieval workloads). For the OED House Rules we plan to use a round guideline of 1/3 and 2/3 body weight for the light and heavy load thresholds. This represents a revision to this prior article.

Finally, I seem to recall a letter or article in Dragon Magazine that pointed out the problem with AD&D horse encumbrance, in particular, that a heavy horseman couldn't move at all. But I can't remember which issue, and asking around online to date hasn't gotten any answers. Do you know of such an issue?

Answered: In the comments below, jbeltman found the letter we were looking for -- in Dragon Magazine #118 (February 1987), Forum p. 6, by David Carl Argall (of La Puente, CA). Huge thanks to jbeltman for that!

Bibliography

  • Bukhari, Syed SUH, Alan G. McElligott, and Rebecca SV Parkes. "Quantifying the impact of mounted load carrying on equids: a review." Animals 11.5 (2021): 1333. -- This is a really great, recent review of all the research to date around the issue of horse carrying capacity.
  • Matsuura, et. al. . Various articles (2012, 2013, 2016, 2018, etc.) -- Matsuura runs a lab in Japan that studies different horse breeds, and keeps coming up with a number close to 30% body weight for the point where any statistical dropoff in performance can be observed.
  • Wickler, S. J., et al. "Effect of load on preferred speed and cost of transport." Journal of Applied Physiology 90.4 (2001): 1548-1551. -- Wickler loaded seven Arabian horses with about 20% body weight burdens, let them walk freely with no rider or lead, and found only about a 5% drop in the speed at which they wanted to walk.

Here's a spreadsheet (ODS) with the tables above if you want to play around with them.

14 comments:

  1. Good stuff, Delta. I play AD&D these days AND use encumbrance, but I tend to research and use actual real world figures unless they closely synch with what the game already has, ESPECIALLY when it comes to pack animals/mounts and loads carried. Most recently I did a whole stretch of research on camels in order to figure out how much weight they carry at what speed across desert terrain and how it affects water consumption.

    [hey, if you're playing an "advanced" game and you have access to the internet, then why not put in the work?]

    Barding hasn't come up (yet) in our game so this isn't an issue I'd caught. As I don't use the Unearthed Arcana for ANYthing, my inclination would be to abstract it: there are three "levels" of warhorse in the PHB, there are three "levels" of barding available, and their are three "levels" over overland movement given for horse mounts (light, medium, and heavy) in the DMG. Until it REALLY matters, I would probably just consider the speeds as listed to INCLUDE reductions based on mount, barding, and rider, since (presumably) Gygax's numbers were based somewhat on research taken from medieval cavalry research.

    I try to keep in mind that the nuts-n-bolts of "coin weight" encumbrance also accounts for bulkiness...that's why many figures are HIGHER than their real world weight (including coins themselves!). See the "folded cloak" versus the "worn cloak" as an example. A broadsword's encumbrance value is more than the weight of the weapon (and scabbard), but must take into account the unwieldy-ness of the thing swinging from your hip. Perhaps the weights given by EGG for barding in Dragon were meant to convey how tough they are to carry by a HUMAN, to prevent players from saying "well, my 18/67 fighter can sling that chain barding from my backpack until I find a mount to replace my dead horse."

    No, sir, you may not...find a cart.

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    1. Great thoughts, very aligned with all that. I'm a big proponent of using (evolving) real-world data to get a stable foundation for this stuff -- and why I'm just a bit queasy at the larger "bulk" interpretation built-in, b/c it's not measurable the same way.

      It's quite reasonable to say those horse moves include the lad weight, although it's counter to the O/AD&D monster listings, so personally I haven't adjusted that detal myself.

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  2. A fascinating and well-done article, thank you very much. I really need to sit down and work through this for my table.

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  3. While many things are the same in AD&D 2nd compared to 1st, this was something that was noticeably revised. Barding was brought in line with historical examples - chain barding is 70 pounds and full plate barding is 85 pounds. However, the loads allowed for horses were also reduced. I suspect that they took the 20% rule of thumb at face value, as full movement is allowed up to 260 pounds encumbrance for a heavy warhorse - if you multiply that by five, it ends up right in the correct range of 1200 to 1400 pounds body weight for a 14th or 15th century destrier. Similarly, a light horse becomes lightly encumbered at 170 pounds, and I've seen 400kg as a ballpark figure for the lighter breeds of medieval horses. Maximum encumbrance in all cases is double the light encumbrance threshold. There are a few more differences, if you have an interest in adding them to your article I could go into more detail. Or you could look them up yourself; while not all on a single page like OD&D, the information is at least all within the Money & Equipment chapter of the PHB.

    There might also be something to be said about reducing their speed at these lower thresholds, considering how high the base movement rates for horses are set in D&D. Like, a light horse moving twice as fast as a man is a reasonable approximation when sprinting, but that doesn't scale down linearly with more usual gaits. Weight is certainly considered a big deal for race horses -successful jockeys are far below average in terms of height and weight - so perhaps reducing a horse's top speed at only 20% body weight encumbrance is more reasonable than you might think. Though perhaps the best of both worlds would be have the higher encumbrance thresholds, but give all horses a base movement speed of around 16 - since their natural walking speed is around 1/3 faster than a human's - plus a separate galloping speed which would differ for light, medium, and heavy horses.

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    1. Ah, good stuff, thanks for looking up the 2E info, as I didn't have time for that! Will be thinking about those other observations.

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  4. Do you have plans to add official stats for horses/beasts of burden and their associated accoutrements to your stone encumbrance system, or should I get off my lazy ass and work on it myself?

    I do really like your system. I based my encumbrance system I worked out for long-term expeditions in DCC largely on what you published earlier.

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    1. Thanks so much! We're working them into our upcoming releases as we speak. In short we assume horse weights of 60-90-120 stone, so light-load limits are 20-30-40 stone. Saddle 1 st., barding 6, man 10.

      Most of that should visible in the OED Expanded rules that we're editing as we speak. (Hopefully Gear table is fixed by the time you see this.)

      http://docs.oedgames.com/OED-Expanded/equipment.html

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    2. That page is so great! Specially the campaign design appendix. Thanks for sharing Delta. A little sugestion is incorporate the posts on demographics there. The advice and rules-of-thumb were helpful to me.

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    3. Thanks! It's something we haven't really announced yet in a big way, Baquies & I are still working on making it presentable. great point about demographics, I'll add it to the list, thanks for that!

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  5. Definitely good to think about. On the other hand, I've seen research that a rider in the saddle is actually less fatiguing than a dead load of the same weight (presumably b/c rider can work with horse to assist balance; can't put my finger on it right now, thought it was in one of those articles in bilbliography). Admittedly I'd expect to hand-wave that and most fatigue issues. A fully fine-grained (maybe computerized) system would make fatigue factors foremost.

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  6. Who has a case for a staff!!!

    The reference in Dragon magazine is below. It appeared in the Forum. As far as I can tell it was never replied to or addressed otherwise.

    Issue 118, Feb 1987, Forum page 6

    Looking over the current AD&D® rules, I note a problem: The knight in shining armor astride his heavy warhorse can’t move.
    A heavy warhorse can carry a maximum of
    7,500 gp weight. Plate barding weights 5,000 gp.
    The knight weighs an average of 1,750. The
    plate mail he wears weights 450 (or 650 if he is in full plate). His large shield weighs 100. For weapons, he has a heavy lance, 150; long sword, 60, and a dagger, 10.
    Thus, we have a total of 7,520 gp weight and we have yet to add any supplies, a missile
    weapon, or any of the dozens of other things a prepared adventurer will want. Just this alone already exceeds the maximum encumbrance the warhorse can carry.
    We can lighten the load on the poor horse, but this should not be necessary. The knight on his heavy warhorse is supposed to be the equivalent of a tank, able to carry a massive load far beyond this minimum level. The heavy war-horse should not be in danger of collapsing if its rider has a heavy lunch. Some of the rules must be altered.
    My own suggestion would be that the weight
    of barding be counted as about 40% for encumbrance purposes — this due to being spread evenly over the horse and thus, not being as great a burden. However, the basic point is that the current rules are completely contrary to both reality and to fantasy as we prefer it. Some changes are needed.
    David Carl Argall
    La Puente, CA

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    1. OMG, you found it! Thanks for that. Appreciate the evidence I'm not hallucinating all these things all the time! (Editing into blog above.)

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  7. Yes, I expect a living, seated rider would be less fatiguing than that same rider would be, dead and draped across the horse's back, for various reasons related to the ability to change the distribution of his weight. But barding is not "dead load" because of its distribution.

    I don't think it would take much in the way of additional mechanics to force this kind of decision-making. One could reduce the effective weight of barding, and impose a tier of weight that didn't impact combat speed but did impact overland speed, perhaps by reducing travel time. And maybe reduce a fatigued mount's speed and/or AC in combat.

    Essentially, if you only use your destrier in combat, it can take the weight without slowing down; but if you use it for travel while in full gear, you reduce travel speed AND combat speed. It would be a pretty easy ad hoc ruling.

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  8. I would make a step back and ask what's the goal of encumberance? Also remember that there is two speed in D&D: dungeon speed and travel speed. I guess the encumberance system should be wilderness travel only because humans can carry another human of same weight for some minutes but can't carry another human of same weight an entire day.

    From what I read animals of human scale can carry for long periods up to 20% bodyweight without issues and after 30% bodyweight the animal start to become injuried. That being said I would use the 20% bodyweight because using 70kg as human average that means humans carry 14kg. Dividing 14kg to 10.5 (Avg Str score) you get 1.333 which is more or less the weight of a sword.

    VoilĂ  you got now the Sword unit of measurement. Perfect fit for D&D and it doesn't stop here.

    An human would weight around 52.5 swords. A light horse seems to weight around 400kg so it would carry around 60 swords enough for carrying an human and some extra things during a light travel. If you are marching to war you can disregards the horse safety and go above to the 30% (or 90 swords) but remember that we are talking about wilderness travel not marching to war or mounted combat. Wikipedia says a suit of plate armor weights between 10 and 20 swords. A knight in heavy armor will exceed the 60 swords that means it's unhealthy for the light horse to travel with that much load and we didn't even taken the sword, shield, barding and all the other things into account.

    Final note: If we back track human weight from the Strength score and 20% carried weight, the Str 3 would mean a 20kg person (avg for 6yo kids) and Str 20 would means 120kg (not that far off for tall strong people). Seems like a good range for me.

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