Every number on this page is arithmetic you can check: Torchline budgets 2,100 XP per character at level 13 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
3,465
4,620
5,775
6,930
Standard — a real fight, rarely lethal
6,300
8,400
10,500
12,600
Hard — someone will probably go down
10,080
13,440
16,800
20,160
Brutal — a character can die here
15,120
20,160
25,200
30,240
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 8,400 does not mean 8,400 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 4,620
A lone threat — about 4,620 XP each (×1 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Bone Devil
Fiend
Large
9
19
142
5,000
Clay Golem
Construct
Large
9
14
133
5,000
Cloud Giant
Giant
Huge
9
14
200
5,000
Fire Giant
Giant
Huge
9
18
162
5,000
Glabrezu
Fiend
Large
9
17
157
5,000
A pair — about 1,540 XP each (×1.5 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 group of four — about 578 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 231 XP each (×2.5 crowd multiplier)