My players have taken a side quest to deliver a chest full of vials of basic poison, and I want a ballpark estimate of how many doses of poison there are in the chest.

Poison, basic (vial); weight: -

Chest; Container Capacity: 12 cubic feet/300 pounds gear

Vial; Container Capacity: 4 ounces liquid

This would be trivial to estimate if the poison had a weight listed, but since it has no listed weight I want to use the listed volumes.

Four fluid ounces is 0.00417752 cubic feet, and 12 cubic feet / 0.00417752 cubic feet per vial = 2,872.5 vials

That's an upper bound since it's not taking into account the space that the glass of the vial would take up, and it assumes perfect packing without empty space. What would a more reasonable estimate be? 1,436, assuming we lose half of the upper bound due to bottle and suboptimal packing? 2,000, just to round down to the nearest thousand? 2,500, to round down to the nearest 500?

I understand that this is getting too specific for the game, since this isn't a reality simulator, but I just want the numbers to be reasonable. I had initially thought "about 100 vials", but that feels incredibly low, looking at all of the space in the chest. Even if we needed room for ensuring vials didn't break in transit, I feel like my initial estimate is still wrong by an order of magnitude.

  • 2
    \$\begingroup\$ if the chest is ever moved perfect packing will result in a LOT of broken vials. \$\endgroup\$
    – John
    Commented Jun 21 at 22:22

5 Answers 5


About 1,100 vials

The weight given for basic poison it is actually "--", the same as the weight of a vial (PHB, p. 150), so technically, it weighs next to nothing, and the limit by the rules will be based solely on volume, as calculated by you.

How many tubes of vials you can actually stack in is a more complicated packing problem (see e.d. How many barrels can fit in a portable hole?). Based on Math Overflows Packing Cylinders in a volume, the packing density is somewhere between 70% if you just pile them in, and 90% if you neatly stack them, but it of course will also depend on the aspect ratio of the vials. As you already ignored the glass thickness, taking the mid-range of this at about 80% would let you stack in about 2,300 vials. I'd round it, just because it is not going to be that exact anyways, as we do not have aspect ratios.

Another approach would be to ignore the rule that these weigh nothing (because if you have that many, the negilible weight will sum up. Basic poison says:

You can use the poison in this vial to coat one slashing or piercing weapon or up to three pieces of ammunition. Applying the poison takes an action.

So you can expect it to be some kind of liquid, or it would not stick, and you could not easily coat your weapon with it. Most poisonous liquids will be water based so they can mix easily with the water-based blood of the victim, so water is a good approximation. One ounce weighs about 30g, and a chest can hold about 136 kg, which would yield over 4,500 ounces, or about 1,100 vials that weigh 4 ounces each.

As you have to observe the lower of the two limits of a container, this would mean you can put about 1,100 vials in there.

  • \$\begingroup\$ Packing density is exactly what I was missing, and using water for a weight comparison is a great idea! \$\endgroup\$ Commented Jun 21 at 16:58
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    \$\begingroup\$ If you look at actual old timey boxes for holding small vials/glass bottles they tend to have little separate compartments for each vial, so that they don't smash into each other. For example a tray or drawer set up in a grid arrangement with wooden dividers, and then several such trays stacked in a box for carrying. The wooden divisions would substantially reduce the available space (search for wooden grid for holding bottles to find some modern equivalents). Other alternatives also tended to lose a fair bit of space. In short, for very small vials the packing would tend to be very "loose". \$\endgroup\$
    – Glen_b
    Commented Jun 24 at 8:44
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    \$\begingroup\$ As 1100 vials are less than half the number possible with dense packing, there is more than half of the space available for lightweight cloth or straw to protect the vials from damage, so this should not be an issue. Maybe you lower the number to a round 1,000 for extra safety and weight reduction. \$\endgroup\$ Commented Jun 24 at 9:24

Base it on how much needs to be shipped, not the size of the containers in the equipment list

In other words, let the narrative guide you, rather than some numbers in the PHB.

A hundred vials of poison is a lot of poison. But maybe for your purpose, it isn't enough. Or maybe it is.

Either way, whether 100 vials or 100 barrels, decide how much should be shipped and that's how much the PCs should transport.

The items in the Equipment chapter in the Basic Rules or the PHB are just there as representative samples, so that players can easily equip PCs. See this answer for details.

If you want to stick as closely to the rules as possible; don't worry, even if you make up your own container sizes, you are sticking to the rules. The beginning of Chapter 5, Equipment says:

In the largest cities, almost anything imaginable is offered for sale, from exotic spices and luxurious clothing to wicker baskets and practical swords.

In even a modest town, there should be some variety of the sizes of chests available, and in a large town or city almost any size of chest might be realistically available. And it seems much more realistic that chests of many sizes are available, not just the one in the equipment list.

Regardless of the number of vials, shipping with lots of packing such as straw is probably a good idea, since having them break would definitely be bad.


Not a rules answer or a math answer, but a logistics answer.

If you have this much poison, you must have a very high-production facility. With high production comes some standardization, especially when it comes to such a shady and cutthroat market. Anyone involved in making this poison needs to be sure every vial has the same amount of poison and that every shipment has the same number of vials, lest you be on the receiving end of an assassin's complaints...

There's also the issue of packaging. You can't just stick that many glass vials in a wooden box — that's asking for trouble, even if they didn't contain deadly poison. So what are they being packed in or packed with? Straw, wool, or cotton would all be common options for the era, with straw being the cheapest (but bulkiest) option.

So, combining these two factors, you're probably going to have vials tied together into bundles that are easy to count and store logistically, packed between bundles of padding. If we just wing it that about half of your space of that upper bound estimate will have to be padding, then round to a nice even number that's easy for the warehouse guys to count, we've got a good starting point of 1,000 vials, packed as bundles of 10.

If you increase or decrease this number, it should be by increments of 10 or 100 unless there are specific logistical reasons why a different number would be required. Maybe if they pack the vials by the dozen, for instance.


The reasonable limit is dictated by the plausible value of poison that would possibly be transported. At 100gp per vial, even 100 vials is the same price as sailing ship as specified in the DMG. 10,000gp.

A chest with 12 cubic feet capacity may seem quite large for a relatively small number of vials but the merchant may reasonably stipulate this just to make it harder to steal, it's hard for one person to carry off a chest. Even two people would move slowly and struggle to quickly hide it. Also, the volume may be used to pack the space around the vials with straw to reduce the risk of the vials being damaged in transit.

100 vials could make sense if each vial is in a large decorative case, each case is packed into a crate of 10 cases, and 10 crates per chest. All with ample amounts of wooden framing between each crate to prevent them colliding with each other and packed with straw around the crates to reduce the chance to damage to the vials if the case if dropped. This can very quickly fill a 12 cubic foot chest.

The chest should be quite heavy when fully loaded but about half the density of water, if it did end up floating down river (hey that's an idea) the water should come up about half way the side of the chest. But when carried it should be about 300lbs. Too heavy for one person to carry.

Then they would have an incredibly valuable and also controversial cargo. Remember, many places ban poisons, many factions would want such a large amount of poison. It would be quite a challenge to transport it.

Hired to transport valuable goods you make about 50% less than if you took the liability of buying the goods and selling them at a profit. Buying and selling for profit you'd expect a 30% cut so 30% of 10,000gp. 3000 gold pieces. As you're only transporters, it's 1500 gold pieces for this mission. Lesser cut as you're not invested if you lose the chest in transit.

I suggest offering your players a choice, 1.5k for a no risk job or take out a loan to buy the 100 vials up-front for the chance to make 3k if they deliver the chest intact. But the risk of being in debt 7k and the need to pay the interest on the debt either way so the longer they take the more it costs them.


Basing it on weight is the best option.

Although there is no weight listed for the Vial, that doesn't mean we don't have information on the weight of the poison. If we had 300 lbs., 4,800 oz. (mass) of poison, and since most liquids have a density close to water, that would equate to 4,800 fluid ounces (volume) of poison, or 1,200 bottles worth. Since this is much lower than the volume criteria, it would certainly govern the capacity.

However, if we consider the fact that even a negligible weight (not even worth mentioning in an adventuring gear table) could be substantial when multiplied by 1,200, then we get into the weeds of how realistic you want to get. But, since you say you want your numbers to be "Reasonable" we can just use modern weights to augment the game so that the numbers are intuitive. A quick internet search leads us to believe that a glass bottle that has a capacity of 4.0 fluid ounces (volume) would have a weight of about 4 oz.(mass) that effectively cuts the number of vials in half to about 600. This probably matches a players intuition that a small empty vial probably weighs about half as much as one that is full. Maybe you round down to 500 to account for packing materials and other containers, like having 50 boxes with 10 in each. Then you could just wave your hand and say that each box of 10 vials weighs 6 pounds, and 300 lbs. means 50 boxes.


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