Every number on this page is arithmetic you can check: Torchline budgets 3,300 XP per character at level 16 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
5,445
7,260
9,075
10,890
Standard — a real fight, rarely lethal
9,900
13,200
16,500
19,800
Hard — someone will probably go down
15,840
21,120
26,400
31,680
Brutal — a character can die here
23,760
31,680
39,600
47,520
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 13,200 does not mean 13,200 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 7,260
A lone threat — about 7,260 XP each (×1 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Behir
Monstrosity
Huge
11
17
168
7,200
Chain Devil
Fiend
Medium
11
16
85
7,200
Djinni
Elemental
Large
11
17
161
7,200
Efreeti
Elemental
Large
11
17
200
7,200
Gynosphinx
Monstrosity
Large
11
17
136
7,200
A pair — about 2,420 XP each (×1.5 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Chimera
Monstrosity
Large
6
14
114
2,300
Drider
Monstrosity
Large
6
19
123
2,300
Invisible Stalker
Elemental
Medium
6
14
104
2,300
Mage
Humanoid
Medium
6
12
40
2,300
Mammoth
Beast
Huge
6
13
126
2,300
A group of four — about 908 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 363 XP each (×2.5 crowd multiplier)