Damage Resistance Damage Resistance ( DR ) is a derived statistic in the SPECIAL character system . Any damage taken is reduced by a percentage based either completely or in part in this number , depending on the game . Damage Resistance can be increased by wearing armor , or by taking certain chem s or perk s , depending on the game . " Fallout " , " Fallout 2 " , " Fallout Tactics " . In the original Fallout games , DR ( Damage Resistance ) is one of three stats by which a character can reduce or avoid damage . The other stats are AC ( Armor Class ) and DT ( Damage Threshold ) . DR occupies the " final step " for combat and simulates the effect of how armor can help diffuse the energy of a bullet and reduce its lethality ( like real - life Kevlar armor ) . More specifically , after AC is checked for a successful hit and after DT is checked to reduce the damage , if there is any incoming damage , DR applies : While DT can completely negate damage done , DR cannot . As the equation suggests , DR is capped at 90 % , and any damage that goes past DT has a minimum of 1 . Initial level : 0 " Fallout 3 " . The maximum Damage Resistance is 85 % , regardless whether this value is obtained by armor , perks , drugs or a combination of these . This makes the effects of Nerd Rage ! and Med - X somewhat less useful , as even without chems , the Lone Wanderer can permanently gain up to 94 % Damage Resistance through equipment and perks ( with " The Pitt " additional content ) . The T - 51b power armor and the Enclave Hellfire power armor plus their respective helmets have a max DR of 60 . Combined with the five permanent perks ( 34 % ) gives the maximum DR without drugs or having less than 20 percent of your hitpoints . Without the additional content you would still be able to obtain a maximum DR of 91 % with power armor . Note that these numbers assume a fully repaired suit of armor , which , when the T - 51b armor is actually being worn , is only possible if the player boosts Crazy Wolfgang ' s repair skill to 100 by reverse pickpocketing workman ' s coveralls from " Point Lookout " onto him because there is only one copy of this armor and it can only be repaired by non - player characters . Enclave Hellfire armor can be found , but it is rare ( only obtainable with Broken Steel loaded ) . For players who prefer non - power armor , you can still obtain a permanent DR of 82 % ( 79 % without " The Pitt " add - on ) with ranger battle armor , ghoul mask , the ranger battle helmet and the perks listed below . " Fallout : New Vegas " . In " " , DR is mostly replaced by DT ( Damage Threshold ) . and the new Slasher and battle brew provide bonuses to DR , which functions identically to the DR from " Fallout 3 " . If all 3 consumables are taken together , they provide the maximum 85 % damage resistance allowed by the game engine . Damage Resistance is applied before damage threshold , contrary to the original Fallout games . So , for a character with 30 DR and 20 DT ( i . e . a NCR Veteran Ranger ) , an attack that deals 80 damage is first reduced by 30 % ( leaving 56 damage ) , then the damage threshold is subtracted from that number , leaving a final damage of 36 . As a result of this , a high damage resistance has a very large effect on a character ' s ability to withstand damage . For full damage formula see . The only pieces of equipment in the game that raise DR instead of DT are : In addition , DR can be conferred via the console by entering player . forceAV DamageResist xx where xx is between 0 and 85 . Values beyond 85 are ignored by the game ; 85 is the maximum DR , a likely holdover in the game engine from Fallout 3 . A rare few non - player character characters have perk s which grant them DR in addition to the DT from their armor . These include : " Fallout 4 " . Damage resistance returns in " Fallout 4 " . However , the stat is no longer a 1 - 1 relationship with actual % damage reduced , as its value can be in excess of 1 , 000 on certain models of power armor . Instead , the amount of damage reduction the Sole Survivor gets out of the damage resistance is actually based on how much potential weapon damage is coming in ; unlike previous games , net damage reduction is based on a ratio between the potential weapon damage done and the damage resistance , with diminishing returns for high damage resistance . The amount of damage reduced by damage resistance climbs very quickly until damage resistance is about half of the potential weapon damage , after which diminishing returns means one gets less and less damage reduction per point of damage resistance . If damage resistance is exactly equal to the potential weapon damage done , then exactly half of the damage is negated . In other words , if one has 50 ballistic damage resistance and is shot by an enemy doing 50 ballistic damage , then they will receive 25 damage . The most important factor is the ratio between damage resistance and potential weapon damage : The upshot is that unlike previous games , it is very hard to get to the point where enemy damage is reduced to the range of ~ 20 % or less . In addition , because the " ratio " between damage resistance and weapon damage is so important and because damage reduction grows very quickly at first for low values of the ratio , a higher damage resistance pays off mostly because it gives the player character better damage reduction against more - damaging attacks , not necessarily because it gives them better damage reduction against the same , weaker attack as before . In other words , going from 20 to 40 damage resistance will only further reduce the damage done from a 10 - damage shot by about ~ 12 % ( ~ 61 % to ~ 69 % damage reduction ) , but it will dramatically boost the player character ' s damage reduction against a 100 - damage grenade by about 23 % ( ~ 10 % to ~ 30 % damage reduction ) . However , significant mitigation against such high damage is harder to achieve , since it is harder to get enough damage resistance to generate an appreciably high resistance - to - damage ratio . In otherwords , getting a 5 - 1 ratio is easy against a 20 damage shot , but very difficult ( essentially limited to power armor ) against a 100 damage grenade . Damage Reduction formula . All final values below are adjusted by difficulty : This is applied after the ratio and exponent are calculated , so damage resistance is applied on the base potential weapon damage , before difficulty - based multipliers are included in . This means that damage resistance is the same level of effectiveness ( or ineffectiveness ) on every difficulty level . Companions are unmodified . On all difficulty levels they do 1x damage and take 1x damage from enemies . This means that companions generally become a bit more effective at higher difficulty levels since they will generally be taking less damage and doing more damage than the player character . Regardless of where one hits an enemy / are hit by an enemy , the total damage resistance of all currently equipped pieces of armor is used for the formula . The actual damage reduction formula is : There are variations on this " DamageCoeff " calculation based on weapon used : For Poison Damage . Poison deals damage each second , as a distinctly inflicted hit , typically for 10 seconds ; for example , if the player character has a poison resistance of 5 and suffers a poison 3 hit , then once per second for 10 seconds , they will suffer a 3 damage hit , resisted with a resistance of 5 , which otherwise follows the rules for projectile damage . For Bleeding Damage . Bleeding works like poison , except that there is no such thing as bleeding resistance . Even robots such as 2nd generation synths and sentry bots will take bleeding damage , as it is a general damage over time effect . For Radiation Damage . Radiation damage has two subtypes . Almost all of it in the game is poisoning ; each point of radiation poisoning from a radiation " hit " is resisted by radiation resistance ( as per the energy damage resistance formula ) , and resolves as a . 1 % loss of maximum HP for each point that gets through . The only perk that raises radiation poisoning damage inflicted by a weapon is Nuclear Physicist , and radiation immunity makes a target ignore radiation poisoning entirely . Non - poisoning radiation damage follows the normal rules for energy damage , including modification by perks ; it ignores radiation immunity , and creatures with radiation immunity typically have no radiation resistance . For Explosive Damage . Explosive modifies other damage types - for example , something can inflict explosive energy damage . Explosive damage uses the same formula as the underlying type , but is affected by additional perks and effects that interact with explosives . Padded and dense armor mods reduce the damage taken by 25 % for padded and 50 % for dense from explosion base damage . E . g . a dense armor mod reduces the damage taken from a frag grenade by 75 ( 150 * 0 . 5 ) in addition to normal physical resistance . Combined Damage Types . When something has multiple resistible damage types ( ballistic , energy , radiation and poison are the currently resistible types , with any of them capable of being explosive or not , and radiation can be poisoning or not - almost all radiation sources are poisoning ) , one " hit " resolves as a hit for each damage type applied . Likewise , when something deals both direct and area of effect damage , a target is hit by each one individually . For example , if one removes the Lorenzo ' s Artifact gun mod from the original gun and attaches it to an Irradiated Gamma gun with an Electric signal carrier antennae , a charged shot from the weapon will inflict 5 distinct " hits " : radiation poisoning , radiation damage , explosive radiation poisoning , explosive radiation damage and explosive projectile damage . Damage Reduction formula for VATS Critical Attack . CriticalDamage = [ PaperDamage x CloseCombatMulti ] + [ WeaponBaseDamage x CriticalMulti ] Armor Piercing . Due to the way the damage formula works , the 40 % armor piercing of some weapons mods actually result in a flat + 20 % effective damage done , on any foe , regardless of the weapon base damage or the DR of the target .