Oblivion:The Complete Damage Formula

Weapon Damage

The complete formula for Blades, Blunts and Bows is:

 Damage = WeaponRating * ( Fatigue / MaxFatigue + 1 ) / 2 * max( SneakMultiplier, PowerAttackMultiplier ) *
          OpponentArmorRating * OpponentWeaponResistance

The WeaponRating (WR) for Bows is the WR for the Bow + the WR for the Arrow.

Where WeaponRating is (both forms are equivalent):

 WeaponRating = BaseWeaponDamage * ( 0.75 + Attribute / 200 ) * 
                ( 0.2 + ModifiedSkill * 0.015 ) * ( WeaponHealth / BaseWeaponHealth + 1 ) / 4
 WeaponRating = BaseWeaponDamage * ( 150 + Attribute ) * 
                ( 40 + ModifiedSkill * 3 ) * ( WeaponHealth / BaseWeaponHealth + 1 ) / 160000

  is the damage value provided on this site for the weapon.
  is the damage shown for the weapon in your character's inventory.
  and   are constrained between 0 and 100.
  is Strength for melee weapons; Agility for bows
  is your skill (Blade, Blunt, or Marksman) modified according to Luck.  The equation is  .    includes any skill-altering magical effects (Fortify, Damage, Absorb, etc; in the form of spells, potions, enchantments, abilities, etc).   also takes into account any magical effects.

Replacing ModifiedSkill directly into the formula yields:

 WeaponRating = BaseWeaponDamage * ( 0.75 + Attribute / 200 ) * 
                ( 0.2 + (Skill + 0.4 * (Luck - 50)) * 0.015 ) * ( WeaponHealth / BaseWeaponHealth + 1 ) / 4
 WeaponRating = BaseWeaponDamage * ( 150 + Attribute ) * 
                ( 3*Skill + 1.2*Luck - 56 ) * ( WeaponHealth / BaseWeaponHealth + 1 ) / 16000

SneakMultiplier is 1 unless your character is sneaking and undetected by the target in which case it is taken from the following table:



Note that only the SneakMultiplier value or the PowerAttackMultiplier will be applied in the final damage calculation. A sneaking power attack attack will not combine the damage multipliers. Assuming optimized skills, the multiplier will either become: 6x from a sneak attack or 3x from a power attack. A sneaking power attack will provide only the 6x multiplier to the final damage calculation.   

PowerAttackMultiplier is the additional damage possible if the attacker chooses to do a power attack instead of a normal attack.
Normally the power attack multiplier is 2.5
If the attacker does a standing power attack and is at least apprentice level, then the power attack multiplier is 3

OpponentArmorRating is 1 if your character is successfully sneaking and has the Master Sneak perk, otherwise it is:
  (100 - CombinedArmorRating) / 100
CombinedArmorRating may not exceed 85.

CombinedArmorRating is the sum of all pieces of armor the opponent is wearing and any boosting effects like Shield.  The rating for each individual piece is:

 BaseArmorRating * ( 0.35 + 0.0065 * OpponentArmorSkill) * ArmorHealth / MaxArmorHealth

OpponentWeaponResistance is the opponent's resistance to normal weapons; if using Silver/Daedric/Enchanted weapons it is always 1.  Otherwise it is:

 (100 - NormalWeaponResistance) / 100


Enchantments on the weapon are handled as a spell hitting the target.  The SneakMultiplier is not applied to either Enchantments or Poisons.

Hand to Hand Damage

The health damage done by Hand to Hand attacks is:
 Health_Damage = 1 + 10.5 * (Strength / 100) * (ModifiedSkill / 100)
The Hand to Hand Skill level is modified by Luck by  .
Hand to hand damage will be increased by the same PowerAttackMultiplier values as weapon attacks.  The damage is also presumably modified by the same Fatigue modifier and OpponentArmorRating as are used for weapon damage.

In addition to health damage, the opponent's fatigue is damaged by the amount:
 Fatigue_Damage = 1 + 0.5 * Health_Damage

Spell Damage

The magnitude of spell damage effects is given by:

 OriginalEffectMagnitude * (100 - MagicResistance + MagicWeakness) / 100

Additionally all Elemental Damage effects are multiplied by

 (100 - ElementalResistance + ElementalWeakness) / 100

:Note: if this multiplier is less than or equal to 0 you will get a message about that effect being resisted.

Modifiable Settings
The equations in the previous sections are applicable when playing vanilla Oblivion.  However, the calculations actually use a large number of modifiable settings, all of which can be altered by mods.  For reference, this section provides the full versions of the equations, including all of the variables that can be altered.

 WeaponDamage = BaseWeaponDamage * fDamageWeaponMult *
    ( fDamageStrengthBase + Attribute / 100 * fDamageStrengthMult ) * 
    ( fDamageSkillBase + ModifiedSkill / 100 * fDamageSkillMult ) *
    ( fDamageWeaponConditionBase + WeaponHealth / BaseWeaponHealth * fDamageWeaponConditionMult )

where the default values for the variables are:
fDamageWeaponMult = 0.5
fDamageStrengthBase = 0.75
fDamageStrengthMult = 0.5
fDamageSkillBase = 0.2
fDamageSkillMult = 1.5
fDamageWeaponConditionBase = 0.5
fDamageWeaponConditionMult = 0.5

The full range of possible SneakMultiplier values are:


The full range of possible PowerAttackMultiplier values are:
Basic power attack multiplier (without any mastery perks): fDamagePowerAttackBonus = 2.5
Standing power attack (Apprentice level perk): fDamagePowerAttackStandBonus = 3
Left and right power attacks (Journeyman level perk): fDamagePowerAttackSideBonus = 2.5
Backwards power attack (Expert level perk): fDamagePowerAttackBackBonus = 2.5
Forward power attack (Master level perk): DamagePowerAttackForwardBonus = 2.5

For Hand to Hand attacks, the full equation for damage is (see also  ):

 Health_Damage = fHandHealthMin + (fHandHealthMax - fHandHealthMin) *
                 (fHandDamageStrengthBase + Strength / 100 * fHandDamageStrengthMult) *
                 (fHandDamageSkillBase + HandToHandModified / 100 * fHandDamageSkillMult)

 Fatigue_Damage = fHandFatigueDamageBase + Health_Damage * fHandFatigueDamageMult

where the default values for the variables are:
fHandHealthMin = 1
fHandHealthMax = 15
fHandDamageStrengthBase = 0
fHandDamageStrengthMult = 0.75
fHandDamageSkillBase = 0
fHandDamageSkillMult = 1
fHandFatigueDamageBase = 1
fHandFatigueDamageMult = 0.5


Other variables that appear to be related to weapon damage:
fMaxArmorRating = 85
fDifficultyDamageMultiplier = 5
fDamageToWeaponPercentage = 0.06 
fDamageToArmorPercentage = 9
fKnockdownDamageMult = 0.3
fHandReachMult = 0.6

See Also
Weapon Damage
Fatigue Modifier
Armor Absorption
Reflect Damage, Reflect Spell