Every number on this page is arithmetic you can check: Torchline budgets 5,500 XP per character at level 19 for a standard fight, scales it by party size, then by the difficulty band. Below each table are the SRD 5.1 creatures that actually land in that budget.
Budgets by party size and difficulty
Difficulty
Party of 3
Party of 4
Party of 5
Party of 6
Skirmish — resources barely dented
9,075
12,100
15,125
18,150
Standard — a real fight, rarely lethal
16,500
22,000
27,500
33,000
Hard — someone will probably go down
26,400
35,200
44,000
52,800
Brutal — a character can die here
39,600
52,800
66,000
79,200
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 22,000 does not mean 22,000 XP of monsters.
What actually fits, for a party of four
The crowd multiplier is the part that catches people out. Two creatures count for 1.5× their XP, three to six count double, seven to ten count 2.5×, eleven or more count triple. So the XP you can spend per creature falls fast as the group grows.
Skirmish — budget 12,100
A lone threat — about 12,100 XP each (×1 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Adult Black Dragon
Dragon
Huge
14
19
195
11,500
Adult Copper Dragon
Dragon
Huge
14
18
184
11,500
Ice Devil
Fiend
Large
14
18
180
11,500
Adult Bronze Dragon
Dragon
Huge
15
19
212
13,000
Adult Green Dragon
Dragon
Huge
15
19
207
13,000
A pair — about 4,033 XP each (×1.5 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Assassin
Humanoid
Medium
8
15
78
3,900
Cloaker
Aberration
Large
8
14
78
3,900
Frost Giant
Giant
Huge
8
15
138
3,900
Hezrou
Fiend
Large
8
16
136
3,900
Hydra
Monstrosity
Huge
8
15
172
3,900
A group of four — about 1,513 XP each (×2 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Air Elemental
Elemental
Large
5
15
90
1,800
Barbed Devil
Fiend
Medium
5
15
110
1,800
Bulette
Monstrosity
Large
5
17
94
1,800
Earth Elemental
Elemental
Large
5
17
126
1,800
Fire Elemental
Elemental
Large
5
13
102
1,800
A swarm of eight — about 605 XP each (×2.5 crowd multiplier)