What really is your Portable Hole's capacity?

[Altair_the_Vexed]

The players' characters in my party have a Portable Hole. As normal, it is listed as having an opening 6 feet wide, and 10 feet deep. I wonfered how much stuff they could fit in there, as they're piling in the armour, weapons, money and other assorted objects that aren't tied down in the dungeon they've been looting.
Consulting this article (http://www.wizards.com/default.asp?x=dnd/rg/20051101a)(link provided by the ever-helpful Lord Silvanos), I find that the Spoooky Wizards figured the volume out as 280 cubic feet (I got 282-ish, but what's 2 cubic feet between friends?).
The article goes on to say that 280 cubic feet can hold about 100,000 coins.

Hang on! 100,000 coins? I had to work this out.

Working backwards from 280 cu ft, we find one coin (assuming 100,000 coins fills the space) is 4.8 cubic inches - that's very large... If it were a quarter inch thick, it'd be 2 and half inches wide, for example. Nothing like the picture in the PHB, which shows a 1 inch diameter coin.

A 4.8 cubic inch coin would have a density of 2.6 kg/L (they're quoted as weighing one fiftieth of a pound each - but excuse me while I switcvh to scientific units for a moment for comparison), which is just 2.6 times the density of water, one seventh of the density of pure gold, less than a third the density of copper, and a lower density than aluminium...

What are they made of? Are they hollow? The only metals I can find of lower density are magnesium and beryllium, which aren't easy to make... Beryllium was first isolated in 1828, and Magnesium was isolated in 1808. The difficulty of getting these metals out of ores (including aluminium) meant that they were far more expensive than gold for a hundred years after their first isolation. Sure, we can get these metals with magic in D&D, but isn't that going to be more expensive than digging up, say, tin?

I reckon the figure quoted in that article is wrong. If the coins are - as shown in the PHB - about an inch in diameter and (let's say) a quarter of an inch thick, then you can fit just less than two-and-a-half-million in the portable hole (if you melted them to take away the empty space between the coins).

We know we have empty space between the coins, so two and a half million is too many. To account for the empty space, imagine they're cuboids with the same dimensions - a quarter inch thick by one inch square. That gives us room for 1.9 million coins. There'd still be some empty space, of course, they'd not be perfectly stacked, so let's call it 1.5 million coins.

That's 15 times more than the figure on the WotC site.

I'll admit my maths may be shaky, and my knowledge of heaping dynamics is only based on some speedy searches on the google academic pages, but a factor of 15 is a really big - and important - difference.

Have I got it all wrong? Is my ability to work out cylinder volumes in error?

[Mr. Friendly]

*begins casting Rule 0*
*finishes casting Rule 0*

The hole can hold an arbitrary volume of items. It contains any amount between some and a lot. It contains this amount until the DM wants to be annoying.

/knows nothing about spacial volumes.

[mostlyharmful]

Yup, WotC got their maths wrong. Gasp of Surprise!:smallwink:

Think of it like a small room, they're expensive enough at 20k and opening them means setting it down on a surface and unfolding it which makes it more awkward than a bag of Holding so just let them cram loads of stuff into it until they start carting around furniture and wagons, then it's full.:smallbiggrin:

[Kurald Galain]

The capacity is precisely one (1) bag of holding.

[Keld Denar]

But....what if the shape inside of the portable hole doesn't follow conventional physics....afterall, a wizard DID do it. So maybe it doesn't follow standard packing rules, which rule that there must be gaps of empty space due to geometry. That would certainly make things a lot easier for computations. I know there are people who EARN A LIVING by calculating the most optimum layout to pack materials of a given geometry into a given space. Why should we do it in a game? (unless thats what you consider fun, then more power to you!) Since it does give us the dimensions, you can't put anything who's dimensions exceed that of the hole, such as a 15' long pole. There is no reason the hole has to conform to other packaging rules though.

[Altair_the_Vexed]

Wow, what a lot of hostility to the idea that the capacity of a carrying device should be consistently defined!

If we're not going to define the inside dimensions (cause yeah, a wizard did it, and we don't have any rules for magic do we? :smallwink:), then it can either be finite, or infinite. If it's infinite, then we have a very different item to the 10 foot deep hole - one that's open to lots of abuse. If it's (as described) finite, and we have a definition of its size and shape (which we do), then how does the 2100 gallons mentioned in the article turn into 140 gallons for coins? What changes the capacity? Is it that they're coins? Is that we added metal? Some explanation is needed - or we could just play Alice In Wonderland and make it all up as we go with little regard to verisimilitude.

Anyway, my point of the post was largely to reason out what the coinage capacity of the Hole was, given that coins are likely to be the most numerous thing thrown in there for long term storage. We know the dimensions when we have to figure out if a boat or a cart will fit, so the coin question seemed most important.

At 15 million coins, I doubt even my greedy players will fill it soon.
And, no, guys, that's not a challenge.