 For the Warframe Cosmetic, see Armor (Cosmetic).
Armor is an attribute that reduces damage taken to health, but not shields. Not all enemies possess armor: Warframes, most bosses, and all Grineer do, but normal Corpus and Infested enemies do not have any. For your Warframe, its armor value is listed in the Arsenal. Armored enemies have their base armor values listed in the Codex but this value increases when they spawn with higher levels. Enemies with more than zero armor have their health bars displayed yellow instead of red; it is possible to strip away armor value through certain abilities or damage procs, turning those enemies' health bars back to red.
In the Damage 2.0 system, health bars always have a health type (flesh, cloned flesh, etc.) which decrease or increase incoming damage depending on damage type ( Toxin, Slash, etc.); armored entities have an additional type on their health called their armor type (either ferrite or alloy) that further decreases or increases incoming damage. This additional type is removed if the armor is stripped.
Effects
Ferrite Armor is one of two armor classes which reduce damage taken to health. Indicated by a yellow hit point bar, it is relatively common with low and midtier Grineer troops such as Lancers and has generally weaker resistances than the more advanced Alloy Armor. As a result of the combination, the best damage to use against these enemies is generally Puncture with Corrosive damage, but resists Slash and Blast damage. Armor has an effectiveness value based on their level, which always reduces damage regardless of type. The full damage calculation then combines this armor value, as well as both the Cloned Flesh and Ferrite Armor's damage modifiers. Note that damage types effective against Ferrite Armor ignore a corresponding percentage of armor in addition to increasing the base damage against enemies with Ferrite Armor. List of Enemies with Ferrite Armor
Trivia
 
Alloy Armor is a health class commonly used by heavy units and bosses. This is one of the two types of armored health classes that provide a damage reduction from the Armor attribute; the other armored health class is Ferrite Armor. Alloy Armor is typically found on the heavyarmament Grineer troops, such as the Napalm and the Bombard, and Corpus Bursas. It is vulnerable to Puncture, Cold, and Radiation damage, and can be reduced through Corrosive status procs, but is resistant to Slash, Electricity, and Magnetic damage. Armor has an effectiveness value based on their level, which always reduces damage regardless of type. The full damage calculation then combines this armor value, as well as both the Cloned Flesh/Flesh/Robotic and Alloy Armor's damage modifiers. Note that damage types effective against Alloy Armor ignore a corresponding percentage of armor in addition to increasing the base damage against enemies with Alloy Armor. List of Alloy Armor EnemiesTrivia

When damage is inflicted to an armored target, there are two related calculations made.
 The working armor value of the target is increased or decreased based off the damage type, armor type, and health type of the weapons and entities involved.
 Incoming damage is reduced by the typemodified armor value according to a damage reduction formula.
Armor Type Modifiers
 See also: Damage 2.0#Damage Calculation
There are two types of armor, Ferrite and Alloy. Both are strong against Slash damage and weak against Puncture. The main difference is in the elemental weaknesses, which are completely different. Ferrite armor is relatively common with low and midlevel enemies such as Lancers and Troopers, and has generally weaker resistances than the more advanced Alloy Armor, which is used by Bombards, Napalm, and other bosses. Ferrite Armor is the armor type of Tenno.
Damage type modifiers inherently affect armor's effectiveness. They are given by the following equation:
Net Armor = Armor × (1 − Armor Type Modifier)
 Armor is your armor value before considering damage types.
 Armor Type Modifier can be found on the nearby charts.
Apart from this armor value modification, type damage modifiers against the armor and health type of the target also plainly multiply the damage. There is a more accurate total damage calculation further down the page, but this section covers the armor value modification.
Damage Reduction Formula
The damage reduction from armor is as follows:
Damage Reduction =  Net Armor 
300 + Net Armor 
A net armor value of 300 will reduce incoming damage by 300 ÷ 600 = 0.5 = 50%, so only half of the weapon's damage is inflicted in total. At 600, you receive only 33% (600 ÷ 900 = 0.67) of a weapon's outgoing damage. At 900 armor, damage is divided by 4 (900 ÷ 1200 = 0.75), and so on.
Effective Health
 Main article: Health#Effective Health
Effective health is the concept that each single point of health you have actually absorbs more than one point of damage, so you effectively have more hit points than indicated. Therefore, there are two ways that armor functionality can be imagined: either as a reduction to damage, or as an increase of effective health and incoming heals. An alternative way to think of armor transforms the above equation to the following:
(  Armor  )  
Effective Health = Nominal Health ×  1 +  
300  
 Nominal Health means "health in name", referring to the Health points in your screen's upper right corner.
 Effective Health becomes your "health in effect", reflecting a "truer" measurement of survivability.
An armor value of 300 will multiply the nominal health with 2, so the effective health will be double the nominal health. At 600 armor, it’s three times the nominal health, and so on. The effective health of a target against a certain damage type is:
(  Nominal Health × (1 +  Armor × (1 − Armor Modifier)  )  )  
Effective Health =  300  
(1 + Health Modifier) × (1 + Armor Modifier)  
The reason it is so important to understand effective health is because it allows you to compare the benefit armor provides to your survivability compared to the benefit that health provides, and it shows you that each additional point of armor increases your time to live by the same amount. While it is common for people to remark that "each point of armor gives you less damage reduction than the previous point", it is not an accurate sentiment—each point of armor confers linear, not diminishing, returns.
Increasing Armor
Mods
Steel Fiber and Armored Agility increase armor value when equipped. As a percentage modifier, Warframes with higher base armor values have a higher benefit from it. Like with most other stats, armor gains from mods stack additively together before being multiplied with the Warframe's base armor:
Total Armor = Base Armor × (1 + Mod Multiplier)
 Mod Multiplier refers to the value on the mods equipped. It is 1.1 at max rank Steel Fiber, 0.45 at max rank Armored Agility, and 1.55 with both equipped.
Neglecting damage type modifiers, the relative increase in effective health from this mod is exactly proportional to the armor increase:
Effective Health Increase = Mod Multiplier × (1 −  1  )  
1 +  Armor  
300 
For example, for Warframes with the common base armor value of 65, a maxed Steel Fiber increases effective health by only about +19.6%, whereas the benefit of a maxed Vitality at level 30 is +246.7%. Valkyr, at 600 base armor, still only gets +73.3% out of a maxed Steel Fiber. However, the effective health increases from Steel Fiber apply as gains from sources of healing—that is to say, increasing armor increases the effective healing received, whereas simply increasing max nominal health does not.
Steel Fiber exists as a mod for sentinels too, while Kubrows can increase armor via Link Armor, as well as via the Kavasa Prime Collar. Link Armor increases their armor by a percentage of the Warframe's total armor, which means that equipping Steel Fiber or Armored Agility on a Warframe directly increases the armor of its Kubrow companion; the Kavasa Prime Collar gives a +100 armor bonus.
Abilities
ENERGY 75 KEY 2  Warcry Valkyr lets out a rallying cry that bolsters her allies melee speed while slowing down nearby enemies.  Strength:15% / 20% / 25% / 50% (speed buff) 25% / 35% / 45% / 50% (armor buff) 15% / 20% / 25% / 30% (slow)  
Duration:7 / 10 / 12 / 15 s  
Range:15 / 20 / 22 / 25 m 
 Armor = Base Armor × (1 + Mod Multiplier + Warcry Modifier)
 Armor = 600 × (1 + 1.1 + 0.5)
 Armor = 1560
ENERGY 50 KEY 2  Hallowed Ground Sanctifies the ground before Oberon with righteous fire, inflicting damage to any enemy that stands in the flames.  Strength:25 / 50 / 75 / 100 (damage) 5% / 10% / 15% / 20% (armor buff)  
Duration:10 / 15 / 17 / 20 s  
Range:5 / 6 / 7 / 7.5 m (length) 2 / 2 / 2.5 / 2.5 m (width) 
 Armor = Base Armor × (1 + Mod Multiplier + Hallowed Ground Modifier)
 Armor = 150 × (1 + 1.1 + 0.2)
 Armor = 345
ENERGY 50 KEY 2  Elemental Ward Depending on Chroma's elemental alignment, an offensive areaofeffect is created. Chroma and his nearby allies are imbued with defensive energy.  Strength:1.5x / 2x / 2.5x / 3x (damage multiplier) 25% / 75% / 100% / 150% (armor boost)  
Duration:10 / 15 / 20 / 25 s  
Range:6 / 8 / 10 / 12 m 
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ENERGY 75 KEY 3  Vex Armor When shields are hit, Chroma's armor grows stronger, when health takes a hit, weapon damage increases. Active for a limited time, maximum increases correspond to rank.  Strength:2x / 2.5x / 3x / 3.5x (max armor multiplier) 100% / 125% / 150% / 175% (max damage bonus)  
Duration:10 / 15 / 20 / 25 s  
Range:N/A 
“It's taking longer than I calculated.” This page is actively being worked on and may not be completely correct. Please assist in making this page accurate.

As shields are depleted while Vex Armor is active, Chroma's armor is increased by 350%. This is a total of 1250 before considering the effect of mods.
 Main article: Hallowed Reckoning
 Main article: Ironclad Charge
Rhino's Rhino Charge (1 ) can be modified with the Ironclad Charge ability augment, which increases his armor by 50%, or 142% with maximized Power Strength, for each enemy hit. This bonus is calculated multiplicatively with other armor modifiers, such as Steel Fiber. A Rhino with a max rank Steel Fiber and unmodified Power Strength that has charged through 5 enemies increases the armor according to the following equation:
 Armor = Base Armor × (1 + Ironclad Modifier × Enemies Struck) × (1 + Mod Multiplier)
 Armor = 190 × (1 + 0.5 × 5 ) × (1 + 1.1)
 Armor = 190 × 3.5 × 2.2
 Armor = 190 × 7.7
 Armor = 1463
In the above example, using Ironclad Charge against 5 enemies increases Rhino's damage reduction from 57.08% at 399 armor to 82.98% at 1463 armor.
Warframe Armor and Effective Health
Unlike health and shield, a Warframe's armor doesn't change as it advances from Rank 0 to Rank 30. Warframe armor is Ferrite and their health class is Flesh. Their armor also never permanently depletes as there are no such effects that remove Warframe armor.
Armor  Damage Reduction  Warframe 

700  70%  Valkyr Prime 
600  66.67%  Valkyr 
475  61.29%  Atlas Prime 
450  60%  Atlas, Nidus (Max Rank) 
425  58.62%  Chroma Prime 
350  53.85%  Chroma, Grendel 
300  50%  Excalibur Prime, Excalibur Umbra, Frost, Frost Prime, Garuda, Hildryn, Nidus (Unranked), Saryn Prime 
275  47.83%  Hydroid Prime, Khora, Rhino Prime, Wukong Prime 
225  42.86%  Excalibur, Hydroid, Inaros, Oberon Prime, Rhino, Saryn, Wukong 
200  40%  Vauban Prime 
190  38.78%  Nezha 
175  36.84%  Ash Prime, Baruuk, Gauss, Harrow, Mirage Prime, Oberon, Wisp 
150  33.33%  Ember Prime, Equinox Prime, Gara, Octavia, Vauban 
125  29.41%  Banshee Prime, Ember, Equinox, Ivara Prime, Limbo Prime, Loki Prime, Mag Prime, Mesa Prime, Nekros Prime, Nova Prime, Nyx Prime, Revenant, Trinity Prime, Volt Prime, Zephyr Prime 
100  25%  Ash, Banshee, Ivara, Limbo, Loki, Mag, Mesa, Mirage, Nekros, Nova, Nyx, Titania, Trinity, Volt, Zephyr 
While there is no such thing as a general effective health value, since effective health depends on the damage type the health is subjected to, a reasonable benchmark to compare the durability of Warframes is their effective health against equally distributed physical damage, i.e. equal portions of Impact, Puncture and Slash, since the vast majority of enemy damage against players is comprised of these types. Inserting these assumptions into the previous formula, we get:
Effective Health_{IPS} = Nominal Health × 60 ÷ 53 × (1 + 67 ÷ 60 × Armor ÷ 300)
As a meaningful PvE benchmark. For actual values, see the figure below.
Enemy Armor
Enemy armor values are displayed under the codex and infobox, but scale to the enemy's level. Generally, only Grineer and boss enemies have armor, while the Corpus and Infested factions do not have any. When the enemy health bars is yellow, armor is in effect and damage will be reduced and cause it to flicker red.
Scaling of enemy armor values uses the following formula:
Armor = Base Armor × (1 + ((Current Level − Base Level)^{1.75} ÷ 200))
 Base Armor: Base armor value for the enemy.
 Current Level: The level of your target enemy.
 Base Level: This is the initial level an enemy can spawn. This is important because certain enemy types, such as Heavy Grineer, will not spawn until certain levels (like level 8 for Heavy Gunners), so while they may be level 30, their armor has only scaled up 22 times.
As mentioned before, this formula causes high level Grineer (lets say up from level 50) to be very hard to kill, as you can see in the example of a level 108 Heavy Gunner:
 500 × (1 + (((108 − 8)^{1.75}) / 200))
 = 500 × (1 + (3162 / 200))
 = 500 × 16.81
 = 8405
Damage Received = Attack Damage ÷ (1 + (8405 / 300)) =
Damage Received = Attack Damage × 0.0345
The resulting damage received by the Heavy Gunner is dramatically reduced to ~3.45% of original damage.
Removing Enemy Armor
There are several effects which reduce enemy armor. If a target's armor is reduced to 0, it loses its armor type. As such, Corrosive damage inflicts significantly more damage to a weakly Ferritearmored enemy than against one whose armor has ultimately been nullified, since apart from the armor mitigation, the +75% damage bonus is lost.
Corrosive Status Procs
 Main article: Corrosive Damage
Corrosive status effects remove 25% of a target's current armor amount, permanently (except in Duels and Conclave, where it only lasts 8 seconds against other Tenno). As a result, each successive proc on the target removes less armor than the previous hit. Even though the armor value should theoretically never hit 0 like this, it does get removed when armor is reduced to below 1, due to rounding.
Mods
 Main article: Corrosive Projection
Corrosive Projection is an aura mod of polarity that persistently reduces the armor of all enemies in the mission by 30%. If multiple cell members equip Corrosive Projection, their effects stack additively: 2 auras reduce enemy armor by 60%, 3 auras reduce enemy armor by 90%, and 4 auras completely eliminate armor from every enemy spawned in the mission entirely. There is no benefit beyond redundancy to having more than 4 auras, in the case of Trial missions with more than 4 cell members.
 Main article: Shattering Impact
Abilities
ENERGY 75 KEY 2  Terrify Casts fear into the hearts of nearby enemies, causing them to run away in terror.  Strength:7 / 12 / 15 / 20 (affected enemies) 5% / 10% / 15% / 20% (armor reduction)  
Duration:10 / 15 / 20 / 25 s  
Range:5 / 10 / 12 / 15 m 
This ability causes affected enemies to flee and reduces their armor by 20% for the duration of the effect. The armor reduction is multiplicative on the target's total armor. Power Strength increases this armor reduction percentage; at maximized strength, Terrify can remove 56.8% of armor from foes.
 Net Armor = Total Armor × (1 − 0.20)
 Main article: Seeking Shuriken
This ability augment makes Shuriken find weaknesses in the target's armor, temporarily reducing its armor values by 70% for 8 seconds at max rank. The armor reduction is multiplicative on the target's total armor. Power Strength increases this armor reduction percentage; at 43%, a Seeking Shuriken removes all armor from a foe.
 Net Armor = Total Armor × (1 − 0.7)
 Main article: Abating Link
This ability augment makes Link drain the targets' armor, temporarily reducing their armor values by 45% for the ability's duration. The armor reduction is multiplicative on the target's total armor. Power Strength increases this armor reduction percentage; at 223%, Abating Link can remove all armor from a foe.
 Net Armor = Total Armor × (1 − 0.45)
 Main article: Fracturing Crush
This ability augment makes Crush strain the targets' armor, temporarily reducing their armor values by 50% for 7 seconds. The armor reduction is multiplicative on the target's total armor. Power Strength does not increase this armor reduction percentage.
 Net Armor = Total Armor × (1 − 0.50)
 Main article: Sonic Fracture
This ability augment makes Sonic Boom strain the targets' armor, temporarily reducing their armor values by 70% for 8 seconds.The armor reduction is multiplicative on the target's total armor. Power Strength can increase this armor reduction percentage and this augment can strip all the armor off of an affected enemy if the power strength is increased above 43%.
 Net Armor = Total Armor × (1 − 0.70)
See also
Damage Mechanics  

Offense  Critical Hit • Damage • Enemy Body Parts • Multishot • Punch Through 
Defense  Armor • Health • Shield 
Damage Types  
Physical  Impact • Puncture • Slash 
Elemental  Cold • Electricity • Heat • Toxin 
Combined  Blast • Corrosive • Gas • Magnetic • Radiation • Viral 
Unique  Tau • True • Void 