For the perk, see Rad Resistance. 
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 antiradiation chems.
”— Fallout Ingame descriptionRadiation Resistance is a derived statistic in Fallout, Fallout 2, Fallout 3, Fallout: New Vegas, Fallout 4, and Fallout Tactics.
It reduces radiation damage by a percentage.
RadX temporarily increases Radiation Resistance.
Fallout, Fallout 2, Fallout: New Vegas, Fallout TacticsEdit
Temporarily increasing Radiation ResistanceEdit
 space suit increases Radiation Resistance by +40% while worn. The
NotesEdit
 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%.
 RadX 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, Radiation 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 3Edit
Example: A starting Endurance of 5.
Permanently increasing Radiation ResistanceEdit
 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 ResistanceEdit
 The RadX drug gives up to +75% Radiation Resistance with the Medicine skill at 100.
 The advanced radiation suit, the environment suit, Lesko's lab coat, Filtration helmet, radiation suit and the modified utility jumpsuit will all increase Radiation Resistance while worn.
 All power armor (other than tribal power armor) has some Radiation Resistance, some more than others.
NotesEdit
 In Fallout 3, Radiation Resistance is capped at 85%.
Fallout 4Edit
Radiation resistance works similar to the other games, but is more crucial because radiation damage itself is much more dangerous than previous titles, lowering your maximum health by 1 percent for every 10 Rads absorbed. Resistance is not gained from Endurance any longer, but now appears on much more equipment, such as vault jumpsuits and gas masks.
Notable resistance effects are still present on radiation suits, now called a Hazmat suit, as well as all forms of Power Armor, which can be modified to offer even more protection, wearing either of these essentially renders the wearer immune to background radiation.
One dose of RadX is no longer an incredibly potent, easytouse form of protection, only offering 100 Rad Resistance. However, multiple doses can be taken, each one stacking for the duration.
Rad Resistance does not work in percentage terms as in earlier games. Power armor can provide over 1000 rad resist; this helps significantly but still does not make one completely immune to radiation. The basic principle is that if your rads/second is exactly equal to your rad resistance, you will take half damage. If you go swimming (10 rads/s in water) with a rad resistance of 10, you will only take 5 rads/s. Higher or lower resistance relative to the radiation level modifies the percent of damage you take, but the effects diminish on both sides; even 5 rad resist will significantly mitigate lowlevel radiation, but rads will still seep through the toughest of power armor.
Permanently increasing Radiation ResistanceEdit
 Rad Resistant perk grants +10 Radiation Resistance per level, up to a maximum of +30 (or +40 with the extra level added in Far Harbor).
 Astoundingly Awesome Tales #10: Grants +5 Radiation Resistance.
Temporarily increasing Radiation ResistanceEdit
 Baked bloatfly: +20 Radiation Resistance for ? minutes.
 Glowing blood pack: +75 Radiation Resistance for 10 minutes.
 RadX: +100 Radiation Resistance for ? minutes.
 Vegetable soup: +25 Radiation Resistance for 1 hour.
Notable apparelEdit
 Hazmat suit: +1000 Radiation Resistance.
 A full set of any Power armor: +1050 Radiation Resistance.
