Every number on this page is arithmetic you can check: Torchline budgets 2,900 XP per character at level 15 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
4,785
6,380
7,975
9,570
Standard — a real fight, rarely lethal
8,700
11,600
14,500
17,400
Hard — someone will probably go down
13,920
18,560
23,200
27,840
Brutal — a character can die here
20,880
27,840
34,800
41,760
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 11,600 does not mean 11,600 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 6,380
A lone threat — about 6,380 XP each (×1 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Aboleth
Aberration
Large
10
17
135
5,900
Deva
Celestial
Medium
10
17
136
5,900
Guardian Naga
Monstrosity
Large
10
18
127
5,900
Stone Golem
Construct
Large
10
17
178
5,900
Young Gold Dragon
Dragon
Large
10
18
178
5,900
A pair — about 2,127 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 798 XP each (×2 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Basilisk
Monstrosity
Medium
3
12
52
700
Bearded Devil
Fiend
Medium
3
13
52
700
Blue Dragon Wyrmling
Dragon
Medium
3
17
52
700
Doppelganger
Monstrosity
Medium
3
14
52
700
Giant Scorpion
Beast
Large
3
15
52
700
A swarm of eight — about 319 XP each (×2.5 crowd multiplier)