Every number on this page is arithmetic you can check: Torchline budgets 120 XP per character at level 2 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
198
264
330
396
Standard — a real fight, rarely lethal
360
480
600
720
Hard — someone will probably go down
576
768
960
1,152
Brutal — a character can die here
864
1,152
1,440
1,728
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 480 does not mean 480 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 264
A lone threat — about 264 XP each (×1 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Animated Armor
Construct
Medium
1
18
33
200
Brass Dragon Wyrmling
Dragon
Medium
1
16
16
200
Brown Bear
Beast
Large
1
11
34
200
Bugbear
Humanoid
Medium
1
16
27
200
Copper Dragon Wyrmling
Dragon
Medium
1
16
22
200
A pair — about 88 XP each (×1.5 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 group of four — about 33 XP each (×2 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Bandit
Humanoid
Medium
1/8
12
11
25
Blood Hawk
Beast
Small
1/8
12
7
25
Camel
Beast
Large
1/8
9
15
25
Cultist
Humanoid
Medium
1/8
12
9
25
Flying Snake
Beast
Tiny
1/8
14
5
25
A swarm of eight — about 13 XP each (×2.5 crowd multiplier)