HOW MUCH IS TOO LITTLE? Calculating Treasure in Dungeons

A common problem quickly encountered when designing your own dungeon or stocking a map drawn by another is the optimal amount of treasure to add. A cousin to that problem could be the "treasure" restocking, again, how much do you add? More distantly related might be if a particular module you picked up is going to contain enough treasure to level a party or at least make the risk worth it?

But it is difficult to understand at a glance because of the alphabet treasure tables (one of my loathes because of complexity), variation due to lairs, if the treasure is trapped or unguarded in which case you employ a different treasure formula (one of my favorites because of simplicity), and even variations in gem quality or type. It is also sometimes difficult to understand how rolling magic items changes treasure distribution.

If you have one or two years of DMing experience under your belt, you have a feel treasure amounts, but you might be like me and think, "Shouldn't someone have already calculated all of this out?"

Well the OSR blogosphere provides! An author by the name of Lungfungus who blogs at Melancholies and Mirth wrote a document brought to my attention on bluskey by blark about just this topic.

While the document contains a lot of good advice about dungeon design, I was particularly enamored with the section on dungeon stocking which synthesizes a lot of different methods of stocking into one table AND answers the question of "how much is enough" when it comes to treasure.

Summary of Actual Dungeon Mastering: How to Design Dungeons

First, on average, 1-in-5 dungeon rooms contain treasure

Lungfungus begins by examining a variety of random stocking methods spanning known editions of D&D from TSR and several popular retroclones. When it comes to treasure-containing rooms, from a TSR edition perspective, they occur roughly every ~4-in-20 rooms (BX methods 10-in-36 and AD&D roughly 4-in-20). A lot of retro-clones, being derived from these two editions, conform to the same distribution.

Second, the average value of a TSR treasure room on Level 1 is 586.5gp

Using the various treasure tables from Appendix A of the AD&D DMG, Lungfungus calculates the average amount of treasure a treasure room might contain and arrives at an average value of 586.5 gold pieces. Fantastic! Let's just round it off to ~600gp for ease.

But each treasure room could instead have a 1-in-6 change of being a magic item instead of coin/gem/goods-based treasure. We can also convert 1-in-6 to ~3-in-20 to keep all our rolls on a d20.

Third, 2000xp is the average need to advance a PC from level 1 to 2

Lungfungus uses a very familiar method of calculating the average total XP needed to level up by taking the average XP needed by a single PC to advance from level 1 to level 2 which is 2000xp. So, a party of 6 PCs needs on average 12,000xp in total to advance from level 1 to level 2.

Now there are a couple of additional calculations I am leaving out such a reducing treasure given that some XP is awarded for monsters and adding 50% more treasure than the required amount given that PCs will often overlook hidden treasure or not explore every single room in a given dungeon.

In that regard, it might be better to use "magic-user" instead of "fighter" when calculating the XP need to advance above given that a MU requires 2500xp vs a fighter's 2000xp.

Fourth, the total size of the dungeon can be determined from the number of treasure rooms required for a given party size to advance from level 1 to level 2

Therefore, since the average value of a treasure room is 586.5gp and the total amount of XP needed is 12,000, then a level 1 dungeon will need at least 20.4 treasure rooms. And so, since 1-in-5 rooms are treasure rooms in the average dungeon, we do a little algebra and solve for X to get the total size of the dungeon:

Total dungeon rooms: (1/5) = (20/X) 

Total dungeon rooms: 1X = 100

Total dungeon rooms: X = 100

Finally, the Lungfungus synthesized stocking method

Roll 1d20 per room and consult the table below:

1-12        Empty Rooms 13            Room with a Dynamic Element

14            Room that is Trapped

15            Room containing an Obstacle 16-20     Monster Treasure Containing Rooms: For any given room, there is 4-in-20 chance it contains treasure and a 3-in-20 chance that treasure is a magic item (6-in-20 if it is trapped); treasure value is ~600gp x dungeon level

The final thing that might be important to realize is that PC XP requirements increase linearly, so all you need to do is multiply the above amounts by the dungeon level to have everything scale properly. So the treasure room amount for Level 7 of the dungeon is ~600gp x 7 = 4,200gp. This seems like a lot however to get a fighter from level 7 to level 8 it takes 64,000 additional xp.