Armor Class (AC) is the protective rating of a type of armor. Armor provides protection by reducing the chance that a character is attacked successfully (and thus suffers damage). Armor does not absorb damage, it prevents it. A Fighter in full plate mail may be a slow-moving target, but penetrating the armor to cause any damage is no small task. Armor Class is measured on a scale from 10, the worst (no armor), to less than zero. The lower the number, the better (armor classes less than –10 occur only with very powerful magical armors). Shields can also improve the AC of a character, as well as certain magic items.

Abilities and situations can also affect a character’s Armor Class. High Dexterity gives a bonus to Armor Class, for example.

When an attack is made, the AC of the opponent being attacked is subtracted from the THAC0 of the attacker. The resulting number is what the attacker must “roll” in order to hit the opponent. This “roll of the die” is done with a d20, or twenty-sided die, resulting in a number between 1 and 20. If the attacker rolls a number equal to or greater than the value necessary, then the attack is successful and damage is done. If the attack is unsuccessful, then the attacker missed completely or was unable to penetrate the opponent’s armor.
For example, a 3rd-level Fighter has a THAC0 of 18. He is attacking a hobgoblin with an AC of 5. The AC of the hobgoblin is subtracted from the THAC0, giving a “to hit” number of 13. If the Fighter rolls a 13 or higher in the twenty-sided die, he hits successfully and does damage.

Body armor and shields armor class. Heavier armors provides better armor class, but the heavier and more protective armors can only be worn by members of the warrior group. Items of duplicate effect may not be worn together.

Armor class in the game files of Baldur's Gate and Baldur's Gate IIEdit

If you look in the games, you have column Parameter 1, which is the number and parameter 2 which determine the type of armor class. There are six types of armor class.

Param 2 value Type armor class Param 2 value Type armor class
16 Basic armor class. 2 Missiles attack armor class bonus.
8 Slashing attacks armor class bonus. 1 Blunt attacks armor class bonus.
4 Piercing attacks armor class bonus. 0 Armor class bonus.

Affecting Base Armor ClassEdit

These will not stack with each other:

All body armor (many body armors have AC bonus enchantment too) and Bracers of Defense.


Ghost Armor

Spirit Armor

Monks' inherent ability

Big Metal Unit *Spoiler*

Bonuses Affecting Armor ClassEdit

These will stack with each other to the AC cap of -26 for warrior classes and -24 for other classes in BG:EE and BGII:EE:

All shields give a bonus to AC = 1 + shield's enchantment value(if any).

Rings and Amulets of Protection (will not stack if AC bonus enchantment is already on body armor).

Dexterity bonuses

Defender of Eastheaven +2


Dak'kon's Zerth Blade

Cloak of the Sewers

Cloak of Balduran

Helm of Balduran

Ring of Gaxx

Ring of Earth Control

Boots of Phasing

Tzu-Zan's Bracers

Wondrous Gloves

Tear of Bhaal (evil path *spoilers*)

Evasion and Greater Evasion

Bard song of Skald Bard Kit and Bards with Enhanced Bard Song

Defensive Spin (Blade Bard Kit)

Kensai kit

Swashbuckler kit

Items Affecting Only Armor Class ModifiersEdit

These will always offer protection (even if at AC -26) as armor class modification is applied against attacking enemy's THAC0 based on the type of damage they would deal upon a successful hit:

Boots of Avoidance

Sword and Shield Style Weapon proficiency

Monks' inherent ability

See also Edit

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