How do I calculate a suitable combat encounter under 5e based on the CR values in the Monster Manual?

Question

In my 3rd ed book, there is a table of CR against the number of monsters a party can fight based on their level. In 5e I cannot find this table. There is some mention of encounters being based on the total exp of the stuff they are fighting but it is just a couple of sentences. However this would make the CR stat in the MM redundant.

Can I re-use the table from 3rd ed or is there a new formula for using the CR in 5e? Or am I missing something completely?

Also, what is the range of CR that they can fight, for example, if the party are found to be able to kill a monster of CR 5 by whatever calculations are used, can they kill a monster of CR 6 or 7 with great difficulty? I seem to recall 3rd ed said you'd expend a certain percentage of resources but I cannot find this in the DMG for 5th edition.

Edit: Page 82 of the Dungeon Master's Guide talks about designing an encounter, but it says nothing about CR, it only talks about creating encounters based on experience.

Answer 1

The sidebar on DMG 82 explains one important aspect of CR: a monster of higher CR than the party's average level is likely to have special features or damage output that is too much for the party to handle.

A monster's CR is equivalent to its XP reward, which is used to build encounters. As MM 9 says, one monster of CR equal to the party's level is a moderate challenge for a party of four characters. If you compare the table on MM 9 to the table on DMG 82, you can see that this is roughly consistent with the encounter building rules.

The DMG does not provide the sort of easy, shortcut rules of thumb that the 4e DMG provides for tossing together an encounter just by eyeballing the CR of the monsters involved. I find the Kobold Fight Club tool invaluable for generating encounters in my campaign.

Answer 2

1. "is there a formula for using the CR?"

No. As @Gregory and @Albert have pointed out, you've got to do the XP-math to evaluate the encounter against the guidelines. Luckily, tools like Kobold Fight Club, spreadsheets, and a head for numbers make it not too onerous to do this until you feel you don't need to any more.

2. "what is the range of CR that they can fight?"

Recall that CR is meant to be a statement that 4 equipped and rested adventurers of the same level as the CR should find the monster a "worthy" challenge (MM p.8, paraphrasing). So let's assume for the moment a party of 4 and a single monster, do the XP-math, and classify each encounter:

• CR=Average Party Level (APL) usually yields a Medium encounter. (Recall the encounter descriptors in "Combat Encounter Difficulty" on DMG p.82.) The exceptions are at levels 5-7, where the "CR-appropriate" monster actually yields an Easy encounter.

• CR=APL-1 usually yields an Easy encounter. The exceptions are at levels 10, 14-16, 18, and 19 where the monster one CR lower than APL still yields a Medium encounter.

• CR=APL+1 starts Deadly, then scales back. At level 1 a CR2 monster is Deadly. During levels 2-4 bumping up the CR by 1 yields a Hard encounter. After that, CR+1 yields Medium encounters.

• CR=APL+2 is... unpredictable. At level 1 a CR3 monster is Super-Deadly^TM. At levels 2-4 CR+2 monsters are Deadly. Level 5: CR+2 is Medium. Levels 6-11: CR+2 is Hard. Levels 12-14: CR+2 is Medium. Levels 15-16: CR+2 is Hard. Levels 17-18: CR+2 is Medium. Levels 19-20: CR+2 is Hard.

Just remember that we assumed both "well-rested" and "single monster." Once you relax either of those assumptions all of this math's out the window, and you need to re-evaluate.

Answer 3

CR is only used for quickly compare monsters, which seems faster than comparing xp. Basically, then, is like a classification of how strong the monster is.

What you need to use is the amount of xp the monster gives (which is directly related to the CR). Therefore, for designing combat encounters, ignore CR and take the amount of xp the encounter gives to check if it's suitable or not (remember to multiply it for the appropiate factor depending the number of monsters).

The XP value of each CR can be found at page 9 of the Monster Manual. – Yotus