How much weight can a backpack carry?

Question

I have been working on my character spreadsheet for carrying capacity and what they are carrying. I keep encountering little issues with this.

Such as a backpack

This leather knapsack has one large pocket that closes with a buckled strap and holds about 2 cubic feet of material. Some may have one or more smaller pockets on the sides.

So it can carry 2 cubic feet of material. I dont see anywhere where a cubic foot of space is given a weight allowance, as most objects you use tend to be listed by weight and not part of a cubic foot. So how can I tell what I can or cant carry?

According to Google, a cubic foot of water weights 62 pounds.

According to Google, a cubic foot of loose dirt is 74 pounds, and densely packed is 100 pounds.

So in the end, what should a cubic foot of space be expected to hold in terms of weight?

Answer 1

Unless the backpack becomes a creature unto itself (via something like animate objects) it does not have a 'maximum' weight. Mostly because going down to that granular a level for random equipment is generally not worth the effort it would take. And, as you, yourself, pointed out, different materials can weigh different amounts, so there is no "standard" definition of how much a cubic foot of material weighs.

Carrying capacity is only affected by magical items, like muleback cords or a bag of holding (which only has an effect in that the things inside it weigh nothing in regards to your carrying capacity), or a masterwork backpack (which raises your effective str score by 1 when calculating carrying capacity). Containers such as barrels, waterskins, backpacks, etc... are more of a convenience for describing how your character is carrying all the random stuff adventurers carry.

As a gm, its far too much work and nowhere near fun enough for me to keep track of the size of everything to make sure it could fit in your various packs as long as it doesn't go over your carrying capacity. Also as a GM, I'd be insane or a giant pain to force my players to keep track of that as well. Saying that, though, its all about what I would deem as reasonable, you could probably throw 1000 coins, some pots and pans, food, and whatnot in a bag and I won't question it, but if you try and fit a 3.5 ft long sword in the bag and not have it be easy to steal, or trying to fit a small cursed item that weighs 1000 lbs in your bag without it ripping I'm gonna question you.

Essentially, its on a GM by GM basis.