Oblivion:Endurance

Endurance is the governing attribute for Block, Armorer, and Heavy Armor. It affects:
Fatigue = Endurance + Agility + Strength + Willpower (NPCs and player)
Base health = Endurance &times; 2 (player only)
Health increase on leveling = Endurance &divide; 10 (rounded down) (player only)
If increasing Endurance on level up: Above + (Increase x 2).
The duration that your character may breathe underwater for before drowning.

In-game Description: Affects how much Fatigue you have, your Health, and how much your Health will increase when you sleep and raise levels. Governs the skills of Block, Armorer, and Heavy Armor.

If your Endurance is increased while leveling, your health will increase both because the base health has increased and because of the health increase on leveling. In other words, base health is recalculated at each level-up after applying any Endurance gains.

 
Character Creation
The Races page provides a table summarizing the initial endurance for each race and gender.
Initial +10 endurance bonuses are possible by selecting either Lady or Warrior as birthsign.
The following standard classes have endurance as a class attribute (initial +5 bonus):
Acrobat, Pilgrim, Scout, Sorcerer, Spellsword, and Warrior
Or any custom class can select endurance as one of its two attributes.

Health Gains
The health gain each time you level is dependent upon the current value of your endurance; this increase is not retroactive. Therefore to get maximum health you need to raise your endurance to 100 as quickly as possible. To illustrate, the following table compares the health for five characters who all reach 100 endurance by level 20.


The minimum Endurance you can start with is 30 and the maximum is 65. Between these two characters, there will be a 37 point difference in maximum health as long as both max out their Endurance as soon as possible. If, however, you neglect to level endurance until as late as possible, a character following the efficient leveling guide, with the maximum level of 46, will have between 384 and 486 health, a deficit of over 100 to a character who started with 30 endurance and maximized it by level 15.

Notes
Any Fortify Endurance effect will also provide a health increase (equal to two times the endurance boost). These effects will not modify the health received when you level.
Conversely, Damage Endurance or Drain Endurance effects cast upon you will decrease your health. In the case of Damage Endurance, this is substantially more expensive than directly casting a Damage Health spell. On the other hand, Drain Endurance is effectively cheaper than Drain Health (although obtaining access to the Drain Endurance effect is very difficult, and draining Endurance only amounts to a temporary decrease in health).
However, using a Damage Endurance or Drain Endurance effect upon NPCs does not decrease their health.
Fortifying endurance to values greater than 100 continues to increase your health and fatigue.
It is possible to permanently increase your base Endurance past 100, allowing you to squeeze out a little bit more health on leveling:
The Knights of the Nine official plug-in confers a permanent bonus to one Attribute upon completing the quest line. Mara's Blessing (obtained by praying at Sir Casimir's tomb) will increase Endurance by +5. Note that an Endurance of 105 will be rounded down to 10 points of health on leveling. Consider taking the bonus early on to benefit from the added Endurance and then switch to a more practical bonus when the extra points are no longer useful.
The Shivering Isles official plug-in has a quest in which the player becomes addicted to a substance called Felldew. As part of this addiction, the player's base Attributes will be lowered by a certain amount depending on the severity of the addiction. Because the base Attribute is lowered, this allows it to be raised back up to 100 and once the addiction is cured, all lowered points will be returned. The maximum Endurance bonus from this method is 10 points, for a total of 110 Endurance (11 health gained per level).
In total, a maximum base Endurance of 115 is possible, although this will be rounded down to a maximum of 11 health gained per level.

See Also
Increasing Attributes: Tips on how to increase endurance.
Magic Items: There are multiple generic items with that fortify the endurance attribute.
Unique Items: A list of unique items, of which several fortify the endurance attribute. These do not include Leveled Items such as those received from quests, or Artifacts.
: Unique items include:
::*Dondoran's Juggernaut is a heavy cuirass that can be obtained from Olfand at the Nord Winds. Among other enchantments the cuirass fortifies your endurance by 10 points.
::*Fists of the Drunkard are a unique pair of heavy gauntlets that can be obtained from Maenlorn at the Flowing Bowl. Among other enchantments, the gauntlets fortify your endurance by 5 points.
::*Ring of Wortcraft is a unique ring that can be obtained from Falanu Hlaalu at the All Things Alchemical. Among other enchantments it fortifies your endurance attribute by 5 points.
::*Circlet of Omnipotence is a unique ring that can be obtained from the non-journal quest The Forgotten Chests of Pale Pass. It fortifies all attributes, except luck, personality and intelligence, by 3 points.