Armor

Armor

Armor reduces the amount of damage you take by a percentage, increasing with the number of armor you have as seen below. Each point of armor increases the amount of damage it effectively takes to kill you by 6.66% per point.

Damage reduction and Effective HP at different Values:

ArmorStat	0	1	2	3	4	5	6	7	8	9	10	15	30	45	60
Dmg Reduction Tooltip (-%)	0	6	12	17	21	25	29	32	35	38	40	50	67	75	80
Effective HP Increase (+%)	0	6.67	13.33	20	26.67	33.33	40	46.67	53.33	60	66.67	100	200	300	400

[For a more complete list of changes per stat point, see Formulas & Values below.]

Effective HP

While the raw amount of % damage reduction goes down with each point of armor, the value of each % point goes up. For example: If you go from 0% reduction to 10%, that 10% reduction means you take 10% less damage. But if you go from 80% damage reduction to 90%, that +10% increase just halved the amount of damage you take.

So while the % Damage Reduction you gain from each armor point goes down, the effect on how much damage you can take before dying from each point remains the same..

Another example: If you have 100 Max HP and 0 armor, it takes 100 damage to kill you. But if you have 5 armor, you reduce the damage by 25%, so now it takes 100/0.75=133 damage to kill you. This amount of theoretical damage it takes to kill you is called 'Effective HP'.

Meaning for every 100 Max HP you have, each 5 points of armor allows you to take an additional 33 damage before dying. Said another way, each point of armor increases your Effective HP by 6.66%.

Negative Armor

If you have negative armor, the damage you take is instead increased by the percentage. Where +15 armor would give 50% damage reduction, -15 armor means you takes 150% damage.

This means that negative armor, unlike positive armor, has strong diminishing returns. Going from 50% damage reduction to 67% (going from 15 to 30 armor) means you take 50% less damage than you were previously. But going from -15 to -30 armor means going from taking 150% to taking 167% damage, which means you just take a relative 11% more damage than before.

As a result, when you play Ghost, who starts with -100 armor (taking 187% damage), it doesn't make a notable difference if you gain +10 or -10 additional armor: it only changes the damage you take between 186% to 188%.

Rounding

The Tooltip for the Damage Reduction from Armor rounds to the nearest whole %. However, the actual damage reduction the game uses does not round, and instead uses the precise number.

Also note that enemy damage is rounded before armor is calculated. So if an enemy would deal 1.6 damage, that is rounded up to 2 damage, then armor is applied to the 2 damage. And then that number is rounded. So you need 6+ armor to reduce 2 damage down to 1, because you need to reduce it to under 1.5 damage for it to round down.

Items

Positive

These items increase your Armor.

Due to Item Tags, the Character(s) Bull, Golem, Knight, Masochist, Pacifist have a higher chance to find these items in the Shop.

Name	Rarity	Effects	Base Price	Limit	Unlocked By	Tags
Barricade	Tier 3	+3 Knockback +8 Armor while standing still. -5% Speed	75			Armor, Stand Still
Duct Tape	Tier 1	+1 Armor +1 Engineering -2 Max HP	20			Armor, Engineering
Exoskeleton	Tier 4	+3 Armor +5% Crit Chance +5 Engineering +5% Speed -2 HP Regeneration -2% Life Steal	90			Armor, Crit Chance, Engineering, Speed
Helmet	Tier 1	+1 Armor -2% Speed	15			Armor
Leather Vest	Tier 2	+2 Armor +6% Dodge -3 Max HP	45			Armor, Dodge
Medal	Tier 2	+3 Max HP +3% Damage +1 Armor +3% Speed -4% Crit Chance	55			Max HP, Damage, Armor, Speed
Metal Plate	Tier 2	+2 Armor -3% Damage	40			Armor
Robot Arm	Tier 4	+3 Melee Damage at the end of a wave +3 Engineering at the end of a wave -1 Max HP at the end of a wave	100		Win a run with Engineer	Melee Damage, Engineering
Triangle of Power	Tier 3	+20% Damage +1 Armor -2% Damage until the end of the wave when you take damage	65			Damage
Warrior Helmet	Tier 3	+3 Armor +5 Max HP -5% Speed	80			Armor, Max HP

Negative

These items decrease your Armor.

Name	Rarity	Effects	Base Price	Limit	Unlocked By	Tags
Big Arms	Tier 4	+12 Melee Damage +6 Ranged Damage +3 Knockback -3% Attack Speed -3% Speed	105		Win a run with Generalist	Melee Damage, Ranged Damage
Community Support	Tier 3	+1% Attack Speed for every current living enemy -2 Armor	75	1	Win a run with Streamer	Attack Speed
Gambling Token	Tier 2	+8% Dodge -1 Armor	50			Dodge
Glass Cannon	Tier 3	+25% Damage -3 Armor	75			Damage
Gummy Berserker	Tier 1	+5% Attack Speed +25 Range -1 Armor	25			Attack Speed, Range
Jet Pack	Tier 4	+15% Speed +10% Dodge -5 Max HP -1 Armor	100			Speed, Dodge
Lucky Coin	Tier 4	+2 Luck for every 1 % Crit Chance you have -2 Armor	105	1		Crit Chance Luck
Night Goggles	Tier 4	+15% Crit Chance +50 Range -3 Max HP -1 Armor	95		Win a run with Ranger	Crit Chance, Range
Stone Skin	Tier 3	+1 Max HP for every 1 permanent Armor you have -6% Attack Speed	80	1	Win a run with Golem	Max HP, Armor
Sunglasses	Tier 2	+10% Crit Chance -1 Armor	50			Crit Chance
Wheelbarrow	Tier 2	-1 Armor +16 Harvesting	40			Harvesting

Mechanics

These Items have Mechanics related to armor.

The Anvil can increase your Armor stat, but is not tagged as an Armor Item.

Name	Rarity	Effects	Base Price	Limit	Unlocked By	Tags
Anvil	Tier 4	A random weapon is upgraded when entering a shop. If you have no weapon to upgrade, you gain +2 Armor instead.	120	1	Win a run with Arms Dealer	None
Stone Skin	Tier 3	+1 Max HP for every 1 permanent Armor you have -6% Attack Speed	80	1	Win a run with Golem	Max HP, Armor

Characters

These Characters start with different Armor, or have mechanics related to their Armor:

Positive Characters

Name	Stats	Unlocked By	Unlocks
Bull	+20 Max HP +15 HP Regeneration +10 Armor HP Regeneration modifications are increased by 50% You explode for 30 (300% 300% 300%) damage when you take damage This explosion has a 1.5x crit multiplier You can't equip weapons	Win a run in Danger 1	Gnome
Masochist	+5% Damage when you take damage until the end of the wave +10 Max HP +20 HP Regeneration +8 Armor -100% Damage	Win a run in Danger 3	Spiky Shield
Knight	+2 Melee Damage for every 1 Armor you have +3 Armor You can't equip ranged weapons You can only equip tier 2 weapons or above % Attack Speed modifications are reduced by 50% Harvesting modifications are reduced by 80%	Win a run in Danger 4	Plasma Sledgehammer
Golem	+20 Max HP Max HP modifications are increased by 33% Armor modifications are increased by 33% +40 % Attack Speed when you have less than 50% health +20 % Speed when you have less than 50% health You can't heal in any way	Finish a wave with 1 HP	Stone Skin

Negative Characters

Name	Stats	Unlocked By	Unlocks
Ghost	+10 Damage with Ethereal weapons +30% Dodge Dodge is capped at 90% -100 Armor	Reach +60% Dodge	Ritual
Speedy	+30% Speed +1 Melee Damage for every 2% Speed you have -100 Armor while standing still -3 Armor	Reach +50% Speed	Fin
Doctor	+200% Attack Speed with Medical weapons +5 HP Regeneration HP Regeneration modifications are increased by 100% +5 Harvesting -100% Attack Speed Armor modifications are reduced by 50%	Heal 200 HP in one wave	Medikit
Artificer	+175% Explosion Damage +4% Explosion Size for every 1 Elemental Damage you have +100% Damage with Tool weapons -100% Damage Armor modifications are reduced by 50%	Kill 15 Enemies with a single explosion	Explosive Shells

Weapons

These Weapons affect Armor:

Name	Class	Damage	Attack Speed	DPS	Crit Damage/Chance	Range	Knockback	Lifesteal	Special Effects	Base price	Unlocked by
Rock	Primitive, Blunt	20(100%) 35(100%) 50(100%) 70(100%)	1.68s 1.61s 1.53s 1.46s	11.9(59%)/s 21.7(62%)/s 32.7(65%)/s 47.9(68%)/s	x1.5 (10%) x1.5 (15%) x1.5 (20%) x1.5 (25%)	150 150 150 150	5 5 5 5	0 0 0 0	-/+1 Armor/+1 Armor, +2 Max HP/+2 Armor, +2 Max HP	10 22 45 91	Default

These Weapons use your Armor stat to deal more damage:

Name	Class	Damage	Attack Speed	DPS	Crit Damage/Chance	Range	Knockback	Lifesteal	Special Effects	Base price	Unlocked by
Spiky Shield	Medieval, Blunt	10(100%) 15(125%) 20(150%) 30(200%)	1.16s 1.16s 1.16s 1.01s	8.6(86%)/s 12.9(107%)/s 17.2(129%)/s 29.7(198%)/s	x2 (3%) x2 (3%) x2 (3%) x2 (3%)	150 150 150 150	20 20 20 20	0 0 0 0		15 31 61 122	Win a run with Masochist

Weapon Classes

These Weapon Classes affect Armor:

Class	Bonuses	Weapons
Blunt	(2)+1 Armor -2% Speed (3)+1 Armor +3 Max HP -4% Speed (4)+2 Armor +3 Max HP -6% Speed (5)+2 Armor +6 Max HP -8% Speed (6)+3 Armor +6 Max HP -10% Speed	Rock   Spiky Shield   Hammer
Ethereal	(2)+6% Dodge Chance -1 Armor (3)+12% Dodge Chance -2 Armor (4)+18% Dodge Chance -3 Armor (5)+24% Dodge Chance -4 Armor (6)+30% Dodge Chance -5 Armor	Ghost Axe   Ghost Flint   Ghost Scepter   Scythe
Medieval	(2)+1 Armor (3)+1 Armor, +3% Dodge (4)+2 Armor, +3% Dodge (5)+2 Armor, +6% Dodge (6)+3 Armor, +6% Dodge	Quarterstaff   Jousting Lance   Spiky Shield   Crossbow   Sword

Formulas & Values

The formula used by the game for calculating Armor's damage reduction value is:

 % Damage taken after armor  = 1 / ( 1 + ( ARMOR / 15 ) )
Tooltip for Damage Reduction % = ROUND( ( 1 - ( DmgReceived% ) ) * 100 )

It can be clearly seen here that it takes 15 armor to doubles your HP. And that the Tooltip rounds the number to the nearest %

This table shows various damage reduction values with different Armor stats. The Dmg Reduction is the one shown by the tooltip. Below is the actual EHP granted by that amount of armor.

For every 1 :

ArmorStat	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Dmg Reduction (-%)	0	6	12	17	21	25	29	32	35	38	40	42	44	46	48	50	52	53	55	56	57	58	59	61	62	63	63	64	65	66	67
Effective HP Increase (+%)	0	6.6	13	20	27	33	40	47	53	60	67	73	80	87	93	100	107	113	120	127	133	140	147	153	160	167	173	180	187	193	200

For every 10 :

ArmorStat	10	20	30	40	50	60	70	80	90	100
Dmg Reduction (-%)	40	57	67	73	77	80	82	84	86	87
Effective HP Increase (+%)	67	133	200	267	333	400	467	533	600	667

For every 100 :

ArmorStat	100	200	300	400	500	...	1000
Dmg Reduction (-%)	87	93	95	96	97	...	99
Effective HP Increase (+%)	666	1333	2000	2666	3333	...	6666

Stats
Max HP	Melee Damage	Crit Chance	Dodge
HP Regeneration	Ranged Damage	Engineering	Speed
Life Steal	Elemental Damage	Range	Luck
Damage	Attack Speed	Armor	Harvesting