Armor Mechanics

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Armor Mechanics covers everything from damage resistances to physical armor limbs.


Every creature in Barotrauma has specific resistances to damage. These resistances change depending on the limb of the creature, as well as the creature itself. Resistances to damage are applied to any incoming damage, with Internal Damage referring to all types of damage.
Here is an example of how resistances would be applied in a real situation. A Crawler is shot with a Handcannon in the tail. The tail of the Crawler has an Internal Damage resistance of 0.75 (25%), whilst the Handcannon deals 70 Gunshot Wound. The total damage dealt to the Crawler is calculated as follows: 70dmg x 0.75 = 52.5 Gunshot Wound.

Weak Points

Weak points are parts of a creature which receive extra damage from specific sources. They have the same rules as resistances, but the damage outcome is different. The same example used previously will be reapplied to highlight this.
A Crawler is shot with a Handcannon in the head. The head of the Crawler has an Internal Damage resistance of 1.5 (150%), whilst the Handcannon deals 70 Gunshot Wound . The total damage dealt to the Crawler is calculated as follows: 70dmg x 1.5 = 105 Gunshot Wound.


Armor is a feature of three creatures within Barotrauma: the Mudraptor's armor which protects all of its body, the Endworm's armor plates which cover the creature entirely, and the Moloch's shell which protects its brain. In its simplest form, armor is a limb with large resistances to damage that sits on top of another limb, thus protecting it. The resistance values of each creature's armor are identical and shown in the table below.

Burn Bleeding Internal Damage
0.25x 0x 0.1x

Armor can be severed from a living creature to expose the vulnerable flesh beneath it. There are many factors that go into severing a limb, which are expanded upon below.

Limb Severance

Limb severance is the main mechanic used to counter armor. It allows certain damage quantities to remove a limb from a living creature, which can either break armor or disable an attack. There are two key factors that make up limb severance.

Minimum Severance Damage

Minimum severance damage is the minimum damage required in a single shot, after resistances have been factored in, to sever a limb. For example: an armor limb has a minimum severance damage of 15. It has an Damage (affliction type) resistance of 0.1x, reducing all incoming sources of damage by 90%. If this limb takes 28 Gunshot Wound damage from a Revolver Round, it would calculate 28dmg x 0.1 = 2.8 total damage. Because 2.8 is lower than 15, there is no chance for the revolver round to sever this limb.

If the damage source is changed to a Railgun Shell for example, the damage calculation changes. A single railgun shell deals 250 Deep Tissue Injury damage, making the new calculation 250dmg x 0.1 = 25 total damage. Because 25 is higher than 15, the limb moves on to the second factor that determines the chance of a limb being severed: Limb Severance Probability.

Limb Severance Probability

The chance to sever a limb once the minimum damage threshold has been reached is determined by two factors: the item's severance chance, and the limb's severance probability. Despite the name, the limb severance probability is located within the creature's joint of the XML file. These values are multiplied together to create the chance of severing the limb. For example, the Revolver Round has a severance chance of 20% (0.2). The Mudraptor's armor has a limb severance probability of 100% (1.0). Providing the minimum severance damage threshold has been passed, the limb severance chance would therefore be calculated as follows: 0.2 x 1.0 = 0.2 (20%) chance to sever the limb.

Tables of Severance Stats

This section will include tables of stats that show the different probabilities of severing a limb against different creatures. This will take a massive amount of time and effort, so please be patient whilst it is being constructed! Example tables are made public below; feedback is always welcome.


Ranged Weapons


Icon Item Damage Limb Severance
Probability (%)
Armor Total Damage Mudraptor Severance Chance(%) Moloch Severance Chance(%) Endworm Severance Chance (%)
Burn Bleeding Gunshot Wound Burn Bleeding Internal Damage
SMG Magazine 0 12.5 12.5 10 0.25x 0x 0.1x 1.25 0 0 0

NOTE: The table above is an demonstration of what the table will look like once it is moved to Cargo. If you have any feedback, please contact me (Wheatley1001) on Discord in the Undertow Games server. The table will remain public until the move to Cargo; feedback is welcome at any time.

Submarine Weapons

Melee Weapons



Armor Penetration

Piercing Ammunition Types

Projectile Deflection

Human Resistances and Armor

Humans, like all Creatures, have resistances to damage as shown in the table below.


Limb Bleeding Lacerations Blunt Force Trauma Bite Wounds Gunshot WoundNote
Head x 0.75 x 0.5 x 0.5 x 0.75 x 0.5 25% chance to gain 10 Concussion after receiving 5 Internal Damage, Blunt Force Trauma, Bite Wounds, Lacerations or Deep Tissue Injury from a single attack. 
Torso x 0.75 x 0.5 x 0.5 x 0.75 x 0.5   
Arms & Legs x 0.75 x 0.5 x 0.5 x 0.75 x 0.5  

A Human can alter their resistances through different Gear which can be worn. Common examples of this include:

All types of gear can be found on the master page.
Resistances are applied successively, so when shot with a Revolver using Revolver Rounds in the torso, a human wearing a diving suit and a gunner's uniform will receive ~8.8 Gunshot Wound:
28dmg - 50% - 30% - 10% = 8.8

Game Mechanics
Game Modes