Every number on this page is arithmetic you can check: Torchline budgets 60 XP per character at level 1 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
99
132
165
198
Standard — a real fight, rarely lethal
180
240
300
360
Hard — someone will probably go down
288
384
480
576
Brutal — a character can die here
432
576
720
864
These are effective-XP budgets: a group of monsters is multiplied up before it is compared against them, so a budget of 240 does not mean 240 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 132
A lone threat — about 132 XP each (×1 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 pair — about 44 XP each (×1.5 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Acolyte
Humanoid
Medium
1/4
10
9
50
Axe Beak
Beast
Large
1/4
11
19
50
Blink Dog
Fey
Medium
1/4
13
22
50
Boar
Beast
Medium
1/4
11
11
50
Constrictor Snake
Beast
Large
1/4
12
13
50
A group of four — about 17 XP each (×2 crowd multiplier)
Creature
Type
Size
CR
AC
HP
XP
Awakened Shrub
Plant
Small
0
9
10
10
Baboon
Beast
Small
0
12
3
10
Badger
Beast
Tiny
0
10
3
10
Bat
Beast
Tiny
0
12
1
10
Cat
Beast
Tiny
0
12
2
10
A swarm of eight — about 7 XP each (×2.5 crowd multiplier)