Am I correctly calculating the difficulty/XP for this encounter for a 15th-level party of 5 PCs?

Question

I am putting together a campaign and have been experimenting with the guidelines for creating encounters and managing difficulty. I've done the math for quite a few encounters at each of the "tier" levels (5th, 11th, 15th) just to get a feel for how it works. One example is below. Does my method look correct?

15th level party, medium difficulty, 5 PCs

XP Threshold: 5(2800) = 14,000 xp
4 monsters so 2x Encounter Multiplier:

1 fire giant 1(2)(5000 xp) = 10000 xp
1 ogre       1(2)( 450 xp) =   900 xp
2 ettins     2(2)(1100 xp) =  4400 xp
                             --------
                             15300 xp

So a wee bit more than the medium difficulty threshold but still less than the hard difficulty threshold. There are a lot of other factors to take into account when designing encounters and this is just back of the cocktail napkin math. A fire giant figures prominently in the campaign and I'm trying to figure out "when" to bring him in should it come to blows.

Answer 1

You calculation is correct.

15th level party, medium difficulty, 5 PCs

XP Threshold: 5(2800) = 14,000 xp  
4 monsters so 2x Encounter Multiplier:  
  
1 fire giant 1(2)(5000 xp) = 10000 xp  
1 ogre       1(2)( 450 xp) =   900 xp  
2 ettins     2(2)(1100 xp) =  4400 xp  
                             --------  
                             15300 xp  

1. Determine XP Thresholds. First, determine the experience point (XP) thresholds for each character in the party. The XP Thresholds by Character Level table below has four XP thresholds for each character level, one for each category of encounter difficulty. Use a character’s level to determine his or her XP thresholds. Repeat this process for every character in the party.

2. Determine the Party’s XP Threshold. For each category of encounter difficulty, add up the characters’ XP thresholds. This determines the party’s XP threshold. You’ll end up with four totals, one for each category of encounter difficulty.

Consulting the XP threshholds table, Medium for a 15th level character is 2,800, so with 5 characters that's 14,000 for a medium encounter, and 21,500 for a hard encounter.

3. Total the Monsters’ XP. Add up the XP for all of the monsters in the encounter. Every monster has an XP value in its stat block.

A fire giant, an ogre, and two ettins is 5,000+450+1,100+1,100 = 7,650 XP.

4. Modify Total XP for Multiple Monsters. If the encounter includes more than one monster, apply a multiplier to the monsters’ total XP. The more monsters there are, the more attack rolls you’re making against the characters in a given round, and the more dangerous the encounter becomes. To correctly gauge an encounter’s difficulty, multiply the total XP of all the monsters in the encounter by the value given in the Encounter Multipliers table.

Consulting the table:

Number of Monsters	Multilpier
3-6	x2

We double 7,650 to 15,300.