There are five main damage types: Physical, Incendiary, Corrosive, Shock, Slag and Explosive.
Conventional (Non-elemental) weapons simply inflict the base damage listed on the weapon's item card. An elemental gun will first inflict the listed base damage of the gun, modifying that damage by the element's effectiveness against the target type, then possibly damage the target again with a separate burst of Elemental Damage. Most elemental weapons have lower listed physical damage.
- Main article: Shield
Armor reduces damage taken by a multiplicative factor. The degree of damage reduction depends on the body part hit and the degree of armor at that part.
Some armored enemies, such as Lance Defenders, can eliminate 100% of damage taken against areas such as their shields. Other enemies, such as Spiderants, have carapaces that offer only partial damage reduction, typically on the order of 75%. All armored enemies have some vulnerable point, and most can be stunned or goaded into revealing that vulnerable point in some fashion.
- Main article: Elemental Damage
- Main article: Critical hit
Critical hits further increase the damage inflicted on the enemy. Different enemies will offer different targets (e.g. head, mouth, eye, abdomen) for criticals, and may suffer different degrees of critical damage, Zombies and Larva Crab Worms being notoriously fragile to criticals. The bonus can be further enhanced by weapon properties (e.g. Jakobs Unforgiven or Jakobs Bessie) and skills (e.g. Lilith's Slayer or Mordecai's Deadly).
- The maximum damage number that is able to be displayed is 99,999 even though the actual damage dealt may be higher.
- Characters will always take 100% of a weapon's listed damage and cannot sustain critical hits, regardless of whether the weapon is wielded by an enemy AI or another player.
- In Borderlands 2, any damage dealt which exceeds 99,999 will be displayed in thousands, with a corresponding red "K" shown with the damage dealt. For instance, if 150,000 damage is dealt, 150K will be displayed.
- In Borderlands 2, as a gimmick, miniscule damage (1-3) is dealt each time the player bounces on an enemy.
All damage taken is modified by the difference in level between the attacker and the target.
|Attacker level − defender level||Damage multiplier|
|6 or more||2|
|−6 or less||0.05|
Weapon damage scales exponentially with weapon level, and player character melee attack and ability damage scale with player level.
Enemies three or more levels above the player take less damage. This is approximately given by