It's come to the point in our game where the party is going to enter the first major dungeon. They started higher level, around level 8, and we have a variable of 5-8 players. The last 3 coming depend on their circumstances that day so please format your answers as if we only have 5 players. (If you've read my other question on power player you'll know one character is so perfectionist built he can kill a CR 14 dragon in 2-3 rounds by himself with a potion.)

I find myself with a problem.

After reading all the core books plus the Dungeonomicon, I have no idea on the right number of monsters to put into the dungeon.

Things I already know

  • How to determine a parties ECL
  • How to determine a single encounters CR
  • How many encounters a 4 man party takes to level based on these two numbers.

I'm expecting the group to level up by the end of this dungeon, possibly twice, and for it to last around 4 sessions, though it might last longer since they've been taking their time.

Things I can do

  • I can build the dungeon layout.
  • I know what types of monsters to include (Aberrations, Kobolds and Lizard Folk, Rock Golems and more).
  • I've even decided a boss monster.

(The campaign is based on the ongoing war between Tiamut and Bahamut, and this dungeon is technically a cave.)

Things I am looking for:

  • How do I decide the number of encounters (fights) inside a single dungeon?

  • How do I adjust that number to accommodate for larger/smaller dungeons?

  • How do I determine an entire dungeons ECL? (Should that number be a range?)

These three things are all I am looking to learn.

(I'm not sure the Encounter Calculator is what I need as it seems to be set up for individual fights inside a dungeon. Not for the entire dungeon itself. )

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    \$\begingroup\$ What does the dungeon need to do? Do you have a party of level X, and need a party of level X+2 after Y sessions in the future. Do you have a party of level X who need Y sessions of engaging dungeon crawl, finishing with a boss of CR X+3? Are you running a world-simulating game, where the dread caves of dragonment are of interest to the party at the moment? \$\endgroup\$ – Caleth Jul 21 '15 at 12:36
  • \$\begingroup\$ @Zakier: By "starting at higher level" I recommend you specify their level(s) when they enter your dungeon/cave. This gives answers the correct context. \$\endgroup\$ – KorvinStarmast Jul 21 '15 at 12:39
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    \$\begingroup\$ I'm not sure this is answerable. With 5 to 8 PCs, the precise math varies wildly (although I'm pretty sure most wing it). Of greater concern, however, is that a lot of this is dealt with in sections of the Dungeon Master's Guide that aren't open content, dealing as they do with character advancement (but apparently utilities are okay). \$\endgroup\$ – Hey I Can Chan Jul 21 '15 at 14:31
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    \$\begingroup\$ I've found that a lot of dungeon building comes down to getting a feel for your players and the kind of challenges they want to face. It's much more subjective than a mathematical formula, just like building encounters themselves. \$\endgroup\$ – David Reeve Jul 21 '15 at 14:48
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    \$\begingroup\$ @Wyrmwood It takes five reopen votes from users with 3k+ reputation to reopen a question. \$\endgroup\$ – SevenSidedDie Jul 22 '15 at 0:01