In a current Pathfinder game I'm running the PCs have decided to take multiple wagons full of mundane items to outposts/remote villages/etc., both as bribes and for business purposes. They are frequently asking me questions such as "how many candles can I fit in a standard barrel?" and "if we buy cabbages, apples, walnuts, and pumpkins, how many can we fit in our wagon?"
Since this is apparently the theme they've settled on, I'm going to let them run with it until they devise some other method of… whatever they're doing. My players do genuinely want this kind of detail. In all fairness, I do as well; I like low-magic campaigns, and in those, logistics like this become increasingly important. However, I'm getting stretched trying to ad-hoc reasonable responses to these, and am looking for a sensible approach without a lot of math each time, while keeping to a relative level of consistency.
Is there a ratio relating the listed weights to volume that I can use to help answer these questions? If there's a ratio, then I could take the CRB's given weights for items and multiply by the ratio to obtain a rough idea of the amount of space an item occupies.
Yes, I know everything varies, and a ton of feathers clearly isn't the same as a ton of bricks, etc., etc. I don't want real-world accuracy, I want a reasonably fast, gameable method so I can ensure consistency during play without taking up lots of time. We're mostly dealing with produce, or the standard trade goods listed in most rule sources, so big density differences are not likely to be an issue that needs to intrude on gameability.
What I'm hoping for is a rough decimal/fraction/percentage comparing weight to volume, so I can just plug in "X pounds of item" and then divide into the given container volumes.
I also don't want to keep guesstimating since that has been, from experience, neither fast nor sufficiently consistent. It's a waste of my time as GM.
Best Answer
While Pathfinder is great at letting the player know what's on his character's body and how much all of that weighs, it's not so good at measuring freight or determining weight and value of household goods. These are better off abstracted into just gp values and raw weights instead of individual fruits and vegetables.
That is, if the players want to spend their table time with their characters haggling over every pumpkin and where the pumpkin will go in their cart and how much the pumpkin weighs and how long until the pumpkin spoils and whether the pumpkin's organically or magically grown or whatever—seriously, if the players want to play Pathfinder: Farmers' Market—the game's not really going to support them very well. Pathfinder's a game of heroic magical adventure, and that sort of agronomical detail is better left to other game systems. No one game is supposed to accommodate all interests, after all.
But, if the players are nonetheless trying to make this work, I suggest abstracting the crap out of this to speed play. For instance, here's a really basic system to get you started that you can repurpose for your campaign:
There you go. Medium crate of expensive goods? 2 gp and 100 lbs. Small box of cheap goods? 1 cp and 10 lbs. Colossal crate of heavy expensive goods? 2,000 gp and 1,000 tons. Easy, quick, playable, and you don't have to count cabbages.
Your players may balk at the minuscule sums their characters earn through such efforts, and they should: being a commoner sucks, and they're doing commoner work, so they're earning commoner wages. They want real money? Go kill some monsters and take their stuff.