The Vault - Fallout Wiki

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The Vault - Fallout Wiki
Radiation resistance
Radiation Resistance.png
Fallout, Fallout 2, Fallout Tactics, Fallout: New Vegas
ModifiesReduction of radiation exposure
Governed ByEndurance, armor, Rad-X
Initial ValueEndurance * 2
Related PerksRad Resistance, Vault City Inoculations
Related TraitsFast Metabolism
Fallout 3, Fallout 4
ModifiesReduction of radiation exposure
Governed ByEndurance, armor, Rad-X
Initial Value(Endurance - 1) * 2
Related PerksCyborg, Rad Resistance, Survival Expert, Booster Shot, Pitt Fighter
Fallout 76
ModifiesAmount of radiation your character is exposed to is reduced by this amount.
Initial Value0

The amount of radiation you are exposed to is reduced by this percentage. Radiation Resistance can be modified by the type of armor worn, and anti-radiation chems.

— Fallout In-game description

Radiation resistance is a derived statistic in Fallout, Fallout 2, Fallout 3, Fallout Tactics, Fallout: New Vegas, Fallout 4, and Fallout 76.

It reduces radiation damage by a percentage.

Rad-X temporarily increases Radiation Resistance.

Fallout, Fallout 2, Fallout Tactics, Fallout: New Vegas


  • Average characters will have a 10% radiation resistance.
  • The Fast Metabolism trait sets initial radiation resistance to 0.
  • The Rad Resistance perk increases radiation resistance by 15% per rank. (10% per rank in FO1)
  • The Vault City Inoculations perk increases radiation resistance by 10%.
  • Rad-X temporarily increases radiation resistance by 50%. Half of it is lost after 24 hours, with resistance returning to its original value after another 24 hours.
  • In Fallout, rad resistance can go as high as 100% (Which is needed to survive The Glow). In Fallout 2, it is capped at 95%, in Fallout: New Vegas, however, it is capped at 85%.

Fallout 3

Example: A starting Endurance of 5.

Permanently increasing Radiation Resistance

Temporarily increasing Radiation Resistance


  • In Fallout 3 rad resistance is capped at 85%.

Fallout 4 and Fallout 76

Damage resistance in both of the Creation Engine games is essentially the same and uses three separate armor types for the three available damage types:

  • DamageResist, used to determine resistance against ballistic or normal weapons - most conventional firearms, melee, and unarmed weapons, as well as creature attacks,
  • EnergyResist, used against weapons dealing energy damage,
  • RadiationResist, used against - what else? - radiation-based weapons.

To determine the damage reduction, the game first checks the following:

  • If target has 0 Armor = 0% DamageReduction
  • If Armor < 15% AttackDamage = 1% Damage Reduction
  • If Armor > 550x Attack Damage = 95% Damage Reduction

Otherwise, it performs the following calculation: [1]

DamageReduction = 1-0.5*(AttackDamage / DamageResist)^0.3653

At extreme values, Energy damage can be nullified, but Ballistic or Normal damage will only be reduced by a max of 95%.