Critical Hit Chance Formula

Critical Hit Chance = PerkModifiers(ConditionPenalty * CritChanceActorValue * WeaponMultiplier) + VATSBonus

PerkModifiers is a function that modifies the input value using any perks active on the actor that have a "Calculate My Critical Hit Chance" Entry Point and returns the result.

ConditionPenalty = fWeaponConditionCriticalChanceMult * WeaponCondition

CritChanceActorValue is an ActorValue. The base value = fAVDCritLuckBase + fAVDCritLuckMult * ActorLuckValue

The value of the CritChance actor value can be increased or decreased by certain abilities, effects, perks, enchanted armors, and consumables. For example, the Finesse perk is implemented by granting the player an ability which increases critical chance by 5. With this perk, the base value calculated from luck is further increased by 5 when calculating the CritChance actor value.

WeaponMultiplier is the "Crit % Mult" specified on the weapon form. For automatic weapons, this value is divided by the "Fire Rate", also specified on the weapon form. For example, an Assault Rifle has a "Crit % Mult" of 1.0, and a "Fire Rate" of 8, so the WeaponMultiplier will be 0.125.

VATSBonus = fVATSCriticalChanceBonus * IsUsingVATS

ActorLuckValue is the actor's luck value.

WeaponCondition is 10 at 100% condition, 5 at 50% condition, and etc.

IsUsingVATS is 1 if the attack is being made with VATS, 0 otherwise.

Game settings used by this formula

Setting	Default	Description
fWeaponConditionCriticalChanceMult	0.1	Used when calculating ConditionPenalty
fAVDCritLuckBase	0	Used when calculating the CritChanceActorValue
fAVDCritLuckMult	1	Used when calculating the CritChanceActorValue
fVATSCriticalChanceBonus	15	Applied as a bonus chance to critically hit when attacking with VATS. A value of 100 adds 100% chance to crit, 15 is 15% chance to crit, etc.