From The Vault

Derived statistic Radiation Resistance Fallout, Fallout 2, Fallout Tactics modifies: Reduction of radiation exposure modified by: Endurance, armor, Rad-X initial level: Endurance * 2 related perks: Rad Resistance, Vault City Inoculations related traits: Fast Metabolism Fallout 3 modifies: Reduction of radiation exposure modified by: Endurance, armor, Rad-X initial level: (Endurance - 1) * 2 related perks: Cyborg, Rad Resistance, Survival Expert, Booster Shot, Pitt Fighter Van Buren modifies: Amount of radiation your character is exposed to is reduced by this amount. initial level:  ? related perks:  ? related traits:  ?

Radiation Resistance is a derived statistic in Fallout, Fallout 2, Fallout 3 and Fallout Tactics.

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. Rad-X temporarily increases Radiation Resistance.

Fallout, Fallout 2, Fallout Tactics

Initial Level: Starting radiation resistance is equal to EN x 2. 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 it's original value after another 24 hours.
• In Fallout, rad resistance can go as high as 100% (needed to survive the Glow). In Fallout 2, it is capped at 95%.

Fallout 3

The maximum amount of resistance you can gain from perks and Endurance in Fallout 3 is 72% in total. You can increase this up to a maximum of 85% with items or drugs.

Permanently increasing Radiation Resistance

• The formula for radiation Resistance is (Endurance-1)*2. Each point of Endurance increases your Radiation Resistance up to a maximum of +18% at 10 Endurance.
• The Cyborg perk gives +10% Radiation Resistance.
• The Rad Resistance perk gives +25% Radiation resistance.
• The Survival Expert perk gives between +2% and +6% Radiation resistance.
• The Pitt Fighter perk from The Pitt gives +3% Radiation Resistance.
• The Booster Shot perk from The Pitt gives +10% Radiation Resistance.

Temporarily increasing Radiation Resistance

• The Rad-X drug gives up to +75% Radiation resistance with the Medicine skill at 100.
• An Advanced Radiation Suit, the Environment Suit, Lesko's Lab Coat, and a Radiation Suit will all increase Radiation Resistance while worn.