Every number on this page is arithmetic you can check: Torchline budgets 4,700 XP per character at level 18 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
7,755
10,340
12,925
15,510
Standard — a real fight, rarely lethal
14,100
18,800
23,500
28,200
Hard — someone will probably go down
22,560
30,080
37,600
45,120
Brutal — a character can die here
33,840
45,120
56,400
67,680
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 18,800 does not mean 18,800 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 10,340
A lone threat — about 10,340 XP each (×1 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Adult Brass Dragon
Dragon
Huge
13
18
172
10,000
Adult White Dragon
Dragon
Huge
13
18
200
10,000
Nalfeshnee
Fiend
Large
13
18
184
10,000
Rakshasa
Fiend
Medium
13
16
110
10,000
Storm Giant
Giant
Huge
13
16
230
10,000
A pair — about 3,447 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 1,293 XP each (×2 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Black Pudding
Ooze
Large
4
7
85
1,100
Chuul
Aberration
Large
4
16
93
1,100
Couatl
Celestial
Medium
4
19
97
1,100
Elephant
Beast
Huge
4
12
76
1,100
Ettin
Giant
Large
4
12
85
1,100
A swarm of eight — about 517 XP each (×2.5 crowd multiplier)