Endurance

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“Stamina and physical toughness. A character with a high Endurance will survive where others may not.”— Fallout In-game description

Endurance is one of the seven primary statistics in the SPECIAL system.

Fallout, Fallout 2, Fallout Tactics

Modifies: Hit Points, Poison & Radiation Resistance, Healing Rate, and the additional Hit Points per level.

Ways to increase Endurance

In Fallout, the Brotherhood of Steel in Lost Hills can perform an operation to permanently increase Endurance by 1, assuming the Vault Dweller can afford it.
Endurance can be permanently raised in Fallout 2 and Fallout Tactics via the Gain perk.
Endurance can be temporarily raised by 3 in Fallout and Fallout 2 by using Buffout.
The Elixir of Life from Fallout Tactics gives +1 EN and +15 HP.

Fallout 3

Modifies: Hit Points, Poison & Radiation resistance (but not damage resistance) and the Big Guns and Unarmed Skills. Endurance also determines the speed the character's oxygen counter counts down when they are holding their breath underwater.

Bobblehead Endurance — *"Always be ready to take one for the team."*

Value	Resistance	Starting Health	Skill Modifiers
1	0%	120	Big Guns +2, Unarmed +2
2	2%	140	Big Guns +4, Unarmed +4
3	4%	160	Big Guns +6, Unarmed +6
4	6%	180	Big Guns +8, Unarmed +8
5	8%	200	Big Guns +10, Unarmed +10
6	10%	220	Big Guns +12, Unarmed +12
7	12%	240	Big Guns +14, Unarmed +14
8	14%	260	Big Guns +16, Unarmed +16
9	16%	280	Big Guns +18, Unarmed +18
10	18%	300	Big Guns +20, Unarmed +20

Endurance-based perks

Perk	Requirement	Level	Additional Requirements
Lead Belly	5	6
Toughness	5	6
Rad Resistance	5	8
Size Matters	5	8
Strong Back	5	8	Strength 5
Life Giver	6	12
Solar Powered	7	20
Rad Tolerance	7	26
Rad Absorption	7	28

Ways to increase Endurance

Permanent

Bobblehead - Endurance (+1)
Intense Training perk (+1)
No Weaknesses perk (will raise base to 5 if below 5.)
Almost Perfect perk (will raise base to 9 if below 9.)

Temporary

Armor and clothing
- Brahmin-skin outfit, Mechanist's costume, wasteland settler outfit, wasteland wanderer outfit (+1)
- Laborer outfit, tattered slave outfit, worn slave outfit (+1)
- All-nighter nightwear (+1)
Buffout (+3)

Fallout: New Vegas

Endurance determines a character's environmental resistances (poison, radiation), Hit Points, and Healing Rate, as well as the starting levels of the Unarmed and Survival skills. It also determines the number of implants allowed.

Endurance-based perks

Perk	Requirement	Level	Additional Requirements
Old World Gourmet	6	2	Survival 45
Lead Belly	5	6	—
Toughness	5	6	—
Rad Resistance	5	8	Survival 40
Stonewall	6	8	Strength 6
Strong Back	5	8	Strength 5
Life Giver	6	12	—
Long Haul	6	12	Barter 70
Atomic!	6	20	—
Solar Powered	7	20	—
Irradiated Beauty	8	22	—
Rad Absorption	7	28	—
Burden to Bear	6	30	Strength 6
Implant GRX	8	30	—

Level names and statistics

Value	Name	Starting HP	Poison/Rad Resist	Skill Modifiers
1	Basically Dead	120	0%/0%	Survival/Unarmed +2
2	Crumbly	140	5%/2%	Survival/Unarmed +4
3	Do Not Bend	160	10%/4%	Survival/Unarmed +6
4	Handle with Care	180	15%/6%	Survival/Unarmed +8
5	Stain-resistant	200	20%/8%	Survival/Unarmed +10
6	Hardy	220	25%/10%	Survival/Unarmed +12
7	Tough-as-nails	240	30%/12%	Survival/Unarmed +14
8	Flame Retardant	260	35%/14%	Survival/Unarmed +16
9	Bulletproof	280	40%/16%	Survival/Unarmed +18
10	Unstoppable	300	45%/18%	Survival/Unarmed +20

Ways to increase Endurance

Permanent

Endurance Implant available at the New Vegas medical clinic (+1)
Intense Training perk (+1)
Completing the quest The Apocalypse or The End will allow raising any one primary statistic by 1.

Temporary

Armor and clothing
Traits
- Claustrophobia (+1 while outdoors, but -1 indoors)
- Early Bird (+2 between 6am and 12pm, but -1 between 6pm and 6am)
Buffout (+3)
Sierra Madre martini (+4)

Notes

If the Courier's Endurance stat is the most extreme (highest or lowest), Doc Mitchell will either say it explains how the Courier is still alive: being "built solid as an oak." (for highest) or that a stiff breeze would tear them in two but a couple of bullets making them "right as rain." (For lowest)
An Endurance of 9 will guarantee the ability to get every implant in the game, the 9 implants by Dr. Usanagi as well as those offered as Perks. This level of Endurance can be reached by initial S.P.E.C.I.A.L. allocation or raising it by the Intense Training Perk or the raise awarded by finishing the Lonesome Road add-on.
The Endurance Implant by Dr. Usanagi *WILL NOT* raise the number of possible implants, although it counts as a permanent raise of the base Endurance score for all other practical purposes, no matter if chosen first.

Fallout 4

“Endurance is the measure of overall physical fitness. It affects your total health and the action point drain from sprinting”

Modifies: Hit Points and the rate that Action Points deplete by while sprinting.

HitPoints = 80 + Endurance \times 5

HitPointsPerLevel=2.5+(Endurance\times .5)

TotalHitPoints=HitPoints+(HitPointsPerLevel\times (CurrentCharacterLevel-1))

rounded down, i.e.:

TotalHitPoints=77.5+(4.5\times E)+(2.5\times L)+(0.5\times E\times L)

rounded down, where E = Endurance and L = Current Character Level.

Leveling Up: In Fallout 4 Endurance is retroactive; increasing it later on in the game will still reward you all the hit points you would have gained with a higher initial statistic. An endurance of 10 will grant you 7.5 HP per level (or 7 and 8 every other level, since health is rounded down). It is possible to increase endurance beyond 10 permanently (e.g. picking up the Endurance bobblehead or using You're SPECIAL! book after reaching maximum Endurance), which will allow the player to gain even more hp per level. There is no Hit Point Cap.

Sprinting

Action Point drain while sprinting:

ActionPointsPerSecond=(1.05-0.05\times Endurance)\times 12.0

Moving Target adds an additional 0.5 multiplier

Game Settings for sprinting:

fSprintActionPointsDrainMult = 12.0
fSprintActionPointsEndBase = 1.05
fSprintActionPointsEndMult = -0.05

In layman's terms, 1 Endurance is equal to a default Action Point drain rate of 12 AP per second, with a reduction of 0.6 AP per second for every additional rank of Endurance, reducing the drain rate to 6.6 AP per second at 10 Endurance.

Note that with 1 Agility, the player has a maximum of 70 AP. This translates to 5.83 seconds of potential full sprinting time at 1 END, 6.14 at 2 END (+0.31 seconds of full sprint), 6.48 at 3 END (+0.34), up to 10.61 seconds at 10 END. However, each point in Agility raises the player's maximum AP by 10 points, which translates to 2 AGL granting 6.67 seconds at 1 END (+0.83), 3 AGL granting 7.5 seconds at 1 END (+0.83), and 10 Agility (160 AP) grants 13.33 seconds at 1 END (+0.83).

Mathematically-speaking, raising Agility is the better way to increase the total time you can sprint, at least until reaching a full sprint time threshold of 16.67 seconds, after which putting points into Endurance becomes more profitable. This threshold is reached at any allocation of 13 additional points into both END and AGL (i.e. END + AGL = 15, an 8:7, 9:6, or 10:5 distribution).

Since SPECIAL is by no means capped, it is possible to affect non-permanent stat increases beyond 10 (11 with bobbleheads obtained after reaching 10 through perk allocation) using equipment and consumables. Under this course of action, the multiplicative AP drain rate at END 14 and AGL 1 equals 200 max AP at END 1 and AGL 14 (16.67 secs of sprint either way) and at 16+ END increases sprint time by full seconds.

These calculations do not include the multiplier added by Moving Target 3, which in turn has a prerequisite of 6 AGL, Level 44, and three ranks).