Fire Resistance

Fire Resistance allows you to resist fire. The higher your Fire Resistance, the less damage you incur from fire-based attacks, such as from fire ants, or from enemies using fire-based weapons like the flamer, heavy incinerator, and the Shishkebab.

Fallout 3

 * The Ant Might or Ant Sight perk can be acquired from Doctor Lesko during the course of the Fallout 3 quest Those!. Either perk grants +25% Fire Resistance.
 * Enclave Hellfire armor grants a +30% Fire Resistance and the Enclave Hellfire helmet a +5%.
 * Applying fire ant nectar will increase Fire Resistance by 25%.

If one has all three of the aforementioned flame-retardant abilities, the total will be 85% fire resistance, making enemies such as Enclave Hellfire troopers or fire ants little to no problem.

Fallout: New Vegas

 * Applying fire ant nectar will increase Fire Resistance by 25%.
 * Using gecko-backed armors from Honest Hearts  will increase by 15%.
 * The scorched Sierra power armor from Lonesome Road increases fire resistance by 25%.
 * Drinking an atomic cocktail will give you fire resistance as well as Energy Resistance.

Fallout 76
the Fireproof perk increases you'r fire resisance by 20 at rank 1 and 40 at rank 2 and 60 at rank 3

Feuerresistenz Résistance au Feu Сопротивляемость огню