Fallout Wiki
Fallout Wiki

General information[]

Weight calculations[]

Every ammunition type has a specific stack size which is used by the game to determine how much the player character's ammunition supply and how much a weapon loaded with ammo weighs.

The engine only looks at the number of stacks in inventory and calculates the total weight based on that amount, rounding up regardless of the actual amount of bullets in a stack. It will also not display the sum weight of an ammunition type, but just a single stack's weight.

E.g. a 10mm SMG has a magazine capacity of 30 bullets, but 10mm ammo has a stack size of 24. As such, the game considers the 10mm SMG loaded with two stacks of 10mm ammo, for a total of 2 pounds.

Ammunition is also traded in stacks, rather than individual bullets, but the price is calculated proportionately.

Unused modifiers[]

A major bug in the Fallout executable (not fixed in the latest patches) prevents any of the ammunition modifiers (Damage modifier, Armor Class modifier, Damage Resistance modifier) from working.

This table lists the intended values in the last columns, but Armor Class and Damage Resistance modifiers are actually 0% and the Damage modifier is 1/1. As such, only the weapon base damage and Critical Hit modifier are used.

List of Fallout ammunition[]

Image Name Type Magazine size Stack Magazine value Value Magazine weight Weight Round value Value to WT Weapons using this ammo Intended values (not used)
AC mod DR mod Damage mod
223fmj .223 FMJ FMJ 50 200 2 100 -20% -20% 1/1
44fmj .44 Magnum FMJ FMJ 20 50 1 50 0% -20% 1/1
44jhp .44 Magnum JHP JHP 20 50 1 50 0% 20% 2/1
10mmap 10mm AP AP 24 100 1 100 0% -25% 1/2
10mmjhp 10mm JHP JHP 24 75 1 75 0% 25% 2/1
12ga 12 gauge shotgun shell shotgun shells 20 225 1 225 -10% 0% 1/1
14mmap 14mm AP AP 30 150 1 150 0% -50% 1/2
5mmap 5mm AP AP 50 120 1 120 0% -35% 1/2
5mmjhp 5mm JHP JHP 50 100 1 100 0% 35% 2/1
9mmBall 9mm ball 9mm 20 100 2 50 0% 0% 1/1
BBS BBs BBs 20 20 2 10 0% 0% 1/1
Explosiverocket Explosive rocket Explosive 1 200 3 66.67 0% -25% 1/1
Flamethrowerfuel Flamethrower fuel Flamethrower fuel 10 250 10 25 -20% 25% 1
DCELLS Microfusion cell Energy Weapons 50 1000 5 200 0% 0% 1
Rocketap Rocket AP AP 1 400 3 133.33 -15% -50% 1/1
CCELLS Small energy cell Energy Weapons 40 400 3 133.33 0% 0% 1

Behind the scenes[]

  • The aforementioned bug in the executable that prevents the modifiers from being applied also likely prevented the developers from realizing that the ammo modifiers did not work with SPECIAL: The absence of any Damage Threshold modifiers suggests they were carried over from GURPS, which only uses Damage Resistance for the purpose of determining damage effects (Passive Defense was abstracted as Armor Class).
  • In GURPS, the damage is determined by rolling d6 for incoming damage (e.g. the Desert Eagle was supposed to deal 3d6 or 3-18 damage), then deducting the Damage Resistance (which is a flat modifier, not a proportional one), and then applying any damage modifiers from ammunition to the resulting value, called penetrating damage. As such, hollow points potentially deal greater damage, but only against unarmored or lightly armored targets; GURPS DR greatly reduces the penetrating damage and the multiplier quickly loses value. Armor piercing ammunition can punch through armor with much more ease, but the effective damage is lower.
  • In SPECIAL, the damage is determined by multiplying incoming damage by the ammo modifier, then applying Damage Threshold effects, and finally reducing the value through Damage Resistance. While evidently intended to simulate the effects of the GURPS calculation, it accidentally rendered armor piercing ammo useless, as the incoming damage is greatly reduced before DT and DR come into play, and ammo modifiers were not updated with DT modifiers.


Ammunition in Fallout