Binding of Isaac: Rebirth Wiki
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Stage HP is a feature of some enemies, granting them extra health the higher the stage number they're encountered in is.

Calculation[ | ]

The formula for an enemy's total health HP is

where Base HP and Stage HP are the defined HP values for the given enemy and displayed in the enemies' pages, Stage is the current stage number as defined internally by the game and min and bound are functions that take the smaller of two values or bound the middle value between the two others respectively.

In practice, this means the enemy gains Stage HP extra health for the first 4 stages, gains nothing for stage 5, and then 4/5ths of Stage HP up to stage 10 after which their health stops increasing.

Chapters map to stage numbers as follows:

Stage number Normal Mode (except in Rebirth)Greed Mode
1 BasementBasement / CellarCellar / (except in Rebirth)Burning BasementBurning Basement / (in Repentance)DownpourDownpour / (in Repentance)DrossDross I BasementBasement / (in Repentance)CellarCellar / (in Repentance)Burning BasementBurning Basement
2 BasementBasement / CellarCellar / (except in Rebirth)Burning BasementBurning Basement / (in Repentance)DownpourDownpour / (in Repentance)DrossDross II CavesCaves / (in Repentance)CatacombsCatacombs / (in Repentance)Flooded CavesFlooded Caves
3 CavesCaves / CatacombsCatacombs / (except in Rebirth)Flooded CavesFlooded Caves / (in Repentance)MinesMines / (in Repentance)AshpitAshpit I DepthsDepths / (in Repentance)NecropolisNecropolis / (in Repentance)Dank DepthsDank Depths
4 CavesCaves / CatacombsCatacombs / (except in Rebirth)Flooded CavesFlooded Caves / (in Repentance)MinesMines / (in Repentance)AshpitAshpit II WombWomb / (in Repentance)UteroUtero / (in Repentance)Scarred WombScarred Womb
5 DepthsDepths / NecropolisNecropolis / (except in Rebirth)Dank DepthsDank Depths / (in Repentance)MausoleumMausoleum / (in Repentance)GehennaGehenna I SheolSheol
6 DepthsDepths / NecropolisNecropolis / (except in Rebirth)Dank DepthsDank Depths / (in Repentance)MausoleumMausoleum / (in Repentance)GehennaGehenna II (except in Rebirth)The ShopThe Shop
7 WombWomb / UteroUtero / (except in Rebirth)Scarred WombScarred Womb / (in Repentance)CorpseCorpse I (except in Rebirth)Ultra GreedUltra Greed
8 WombWomb / UteroUtero / (except in Rebirth)Scarred WombScarred Womb / (in Repentance)CorpseCorpse II -
9 (except in Rebirth)?????? -
10 CathedralCathedral / SheolSheol -
11 ChestChest / Dark RoomDark Room -
12 (in Afterbirth † and Repentance)The VoidThe Void -
13 (in Repentance)HomeHome -

Example[ | ]

Consider a DipDip with 3 base HP and 1 stage HP.

  • Basement I, i.e. stage 1: HP = 3 + (min(4, 1) + 0.8 * bound(0, 1 - 5, 5)) * 1 = 3 + (1 + 0.8 * 0) * 1 = 4
  • Womb II, i.e. stage 8: HP = 3 + (min(4, 8) + 0.8 * bound(0, 8 - 5, 5)) * 1 = 3 + (4 + 0.8 * 3) * 1 = 9.4
  • The Void, i.e. stage 12: HP = 3 + (min(4, 12) + 0.8 * bound(0, 12 - 5, 5)) * 1 = 3 + (4 + 0.8 * 5) * 1 = 11

Monsters and Bosses that use Stage HP[ | ]

A total of 52 Monsters and 18 Bosses use this mechanic, with the Sins counted among the latter group.

Name ID Base HP Stage HP
Baby Begotten
Baby Begotten
(in Repentance)
883.0 18 3
Baby Long Legs
Baby Long Legs
206.0 16 4
Big Corn
Big Corn
(in Repentance)
217.3 6 2
Black Bony
Black Bony
(except in Rebirth)
277.0 8 2
Black Maw
Black Maw
225.0 20 6
Blister
Blister
(in Afterbirth † and Repentance)
303.0 16 8
Bloodfly
Bloodfly
(in Repentance)
61.6 6 1
Blue Gaper
Blue Gaper
(except in Rebirth)
297.0 (in Afterbirth) 30
(in Afterbirth † and Repentance) 16
(in Afterbirth) 0
(in Afterbirth † and Repentance) 2
Bone Fly
Bone Fly
(in Repentance)
25.4 8 3
Bony
Bony
227.0 8 2
Boom Fly
Boom Fly
25.0 (except in Repentance) 20
(in Repentance) 8
(except in Repentance) 0
(in Repentance) 3
Bulb
Bulb
(in Repentance)
61.5 10 2
Butt Slicker
Butt Slicker
(in Repentance)
878.0 16 3
Clickety Clack
Clickety Clack
(in Repentance)
889.0 20 3
Cloggy
Cloggy
(in Repentance)
872.0 15 2
Crazy Long Legs
Crazy Long Legs
207.0 16 4
Crispy
Crispy
(in Afterbirth † and Repentance)
226.2 12 4
Dank Squirt
Dank Squirt
(except in Rebirth)
220.1 15 6
Dip
Dip
217.0 3 1
Dragon Fly
Dragon Fly
(in Repentance)
25.3.0 8 3
Dragon Fly X
Dragon Fly X
(in Repentance)
25.3.1 8 3
Drip
Drip
(in Repentance)
870.0 3 1
Drowned Boom Fly
Drowned Boom Fly
(except in Rebirth)
25.2 (except in Repentance) 20
(in Repentance) 8
(except in Repentance) 0
(in Repentance) 3
Dump
Dump
(in Repentance)
876.0 10 1
Dump Head
Dump Head
(in Repentance)
876.1 10 1
Eggy
Eggy
(in Repentance)
29.2 20 2
Fetal Demon
Fetal Demon
(in Repentance)
886.1 40 3
Flesh Maiden
Flesh Maiden
(in Repentance)
880.0 24 4
Fly Trap
Fly Trap
(in Repentance)
873.0 16 6
Grub
Grub
239.0 10 2.5
Gurgling
Gurgling
237.0 24 4
Hardy
Hardy
(in Repentance)
826.0 15 6
Holy Bony
Holy Bony
(in Repentance)
227.1 60 14
Holy Eye
Holy Eye
(in Repentance)
60.2 20 5
Holy Mulligan
Holy Mulligan
(in Repentance)
22.2 40 3
Leper Flesh
Leper Flesh
(in Afterbirth † and Repentance)
310.1 5 1.5
Ministro
Ministro
(in Afterbirth † and Repentance)
305.0 9 2
Planetoid
Planetoid
(in Repentance)
229.1 28 4
Polty
Polty
(in Repentance)
816.0 14 2.5
Portal
Portal
(in Afterbirth † and Repentance)
306.0 9 5
Red Boom Fly
Red Boom Fly
25.1 (except in Repentance) 20
(in Repentance) 8
(except in Repentance) 0
(in Repentance) 3
Red Ghost
Red Ghost
(except in Rebirth)
285.0 (except in Repentance) 25
(in Repentance) 20
(except in Repentance) 5
(in Repentance) 4
Rotty
Rotty
226.1 16 5
Sick Boom Fly
Sick Boom Fly
(in Repentance)
25.5 8 3
Skinny
Skinny
226.0 10 4
Small Baby Long Legs
Small Baby Long Legs
206.1 12 4
Small Crazy Long Legs
Small Crazy Long Legs
207.1 12 4
Splasher
Splasher
238.0 10 2
Splurt
Splurt
(in Repentance)
871.0 15 6
Squirt
Squirt
220.0 15 6
Swarm Spider
Swarm Spider
(in Repentance)
884.0 4.5 0.2
Tainted Mulligan
Tainted Mulligan
(in Repentance)
22.3 120 8
Tainted Sucker
Tainted Sucker
(in Repentance)
61.7 14 1
Vis Fatty
Vis Fatty
(in Repentance)
886.0 40 4
Wizoob
Wizoob
219.0 (except in Repentance) 25
(in Repentance) 20
(except in Repentance) 5
(in Repentance) 4
Headless Horseman
Headless Horseman
82.0 160 30
The Fallen
The Fallen
81.0 60 45
Krampus
Krampus
81.1 60 45
Envy
Envy
51.0 (in Rebirth) 60
(except in Rebirth) 40
7.5
Gluttony
Gluttony
49.0 60 (except in Repentance) 15
(in Repentance) 20
Greed
Greed
50.0 60 (except in Repentance) 15
(in Repentance) 20
Lust
Lust
47.0 60 (except in Repentance) 15
(in Repentance) 20
Pride
Pride
52.0 60 (except in Repentance) 15
(in Repentance) 20
Sloth
Sloth
46.0 60 (except in Repentance) 15
(in Repentance) 20
Wrath
Wrath
48.0 60 24
Super Envy
Super Envy
51.1 (in Rebirth) 60
(except in Rebirth) 40
7.5
Super Gluttony
Super Gluttony
49.1 60 (except in Repentance) 15
(in Repentance) 25
Super Greed
Super Greed
50.1 60 (except in Repentance) 15
(in Repentance) 25
Super Lust
Super Lust
47.1 60 (except in Repentance) 15
(in Repentance) 25
Super Pride
Super Pride
52.1 60 (except in Repentance) 15
(in Repentance) 25
Super Sloth
Super Sloth
46.1 60 (except in Repentance) 15
(in Repentance) 25
Super Wrath
Super Wrath
48.1 60 (except in Repentance) 24
(in Repentance) 30
Ultra Pride
Ultra Pride
46.2 85 (except in Repentance) 15
(in Repentance) 25

Trivia[ | ]

  • (in Repentance) The WizoobWizoob and Red GhostRed Ghost are the only entities whose Stage HP were reduced in Repentance, both from 5 to 4.
  • (in Repentance) The Monster with the lowest Stage HP (and with the lowest amount among all entities) is the Swarm SpiderSwarm Spider at 0.2, while the Monster with the highest is the Holy BonyHoly Bony with a staggering 14, nearly twice the amount of 2nd place. All other Monsters have an amount between 1 and 8.
  • The Boss with the highest Stage HP (and with the highest amount among all entities) is a tie between Boss Krampus ingameKrampus and Boss The Fallen ingameThe Fallen at 45. All other Bosses have an amount between 7.5 and 30.


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