Every number on this page is arithmetic you can check: Torchline budgets 450 XP per character at level 5 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
743
990
1,238
1,485
Standard — a real fight, rarely lethal
1,350
1,800
2,250
2,700
Hard — someone will probably go down
2,160
2,880
3,600
4,320
Brutal — a character can die here
3,240
4,320
5,400
6,480
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 1,800 does not mean 1,800 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 990
A lone threat — about 990 XP each (×1 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 pair — about 330 XP each (×1.5 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Ankheg
Monstrosity
Large
2
14
39
450
Awakened Tree
Plant
Huge
2
13
59
450
Azer
Elemental
Medium
2
17
39
450
Bandit Captain
Humanoid
Medium
2
15
65
450
Berserker
Humanoid
Medium
2
13
67
450
A group of four — about 124 XP each (×2 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Ape
Beast
Medium
1/2
12
19
100
Black Bear
Beast
Medium
1/2
11
19
100
Cockatrice
Monstrosity
Small
1/2
11
27
100
Crocodile
Beast
Large
1/2
12
19
100
Darkmantle
Monstrosity
Small
1/2
11
22
100
A swarm of eight — about 50 XP each (×2.5 crowd multiplier)