I have a very limited understanding of D&D concepts. How does weapon damage work in Baldur's gate?

  • @Raven good information. I have attempted to look this up before and hit a stone wall of D&D jargon :S
    – Aardvark
    Jan 19 '11 at 20:04
  • @Taboo -- I was mistaken, it actually used a variant of the 2nd edition rules, so even earlier than the current 4th edition. Jan 19 '11 at 20:12

Baldur's gate I & II use a modified AD&D 2nd edition, if I'm not mistaken.

The damage itself is expressed in dice, so e.g. 1D6 means you throw one six-sided die and count the sum of it. 2D8 means you throw two eight-sided dice and count the sum of the two dice. The damage gets subtracted from the hitpoints of your enemy.

Armor class (AC) defines the probability of getting hit. The attacker throws a D20 and if the value is lower than your AC you are hit, else the attacker misses. Certain bonuses apply to attacker and defender. You have to pay attention to your THAC0, which tells you what you have to throw to hit an enemy with an AC of 0.

Damage type also matters with certain armors having more or less protection vs certain types or are immune to some types of damage outright. This will normally be listed in the weapon description. Extra armor penalties/bonuses are listed in the character sheet near the bottom, or in the armor's description if you're playing in one of the Enhanced Edition games.

  • damages and THAC0 also gets modified by the strength modifier of the character, which is a bonus to the aforementioned die. exemple: 2d6+3 would range between 5 to 15. so the die depends on the weapon, and the modifier on the character.
    – Fractal
    Jan 19 '11 at 20:55
  • If I remember correctly, the already modified THAC0 is displayed in Baldur's gate. Jan 19 '11 at 20:56
  • approved, in your character section. what games those were!
    – Fractal
    Jan 19 '11 at 21:03
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    @Fabian so if I have a 2D18 +2 weapon for example, It does a RNG calculation on both dice (say 12 and 6) adds them together (18) and then adds 2 (20 overall damage)?
    – Aardvark
    Jan 19 '11 at 22:06
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    @Fabian I meant that the values of each D18 (18 sided dice) rolled to 12 and 6... But I think I get the idea
    – Aardvark
    Jan 19 '11 at 22:15

Damage is expressed in terms of thrown dice.


  • Battle Axe ( 1d8, 1-8 dmg, 4.5 average )
  • Dagger ( 1d4, 1-4 dmg, 2.5 average )
  • Club ( 1d6, 1-6 dmg, 3.5 average )
  • Flail ( 1d6+1, 2-7 dmg, 4.5 average )
  • +5 Two Handed Sword ( 1d12+5, 6-17 dmg, 11.5 average )

Formula for attacking:

  • Attack Roll = Attacker THAC0 - Victim AC

A d20 die is thrown, and the value must be greater than or equal to the attacker's attack roll value. The roll auto fails on 1, and criticals on 20. Let's say, for example, I'm the Slayer, and I have a THAC0 of 1; I attack a creature with an armour class of -10; My attack roll would now be 11 (50% chance to hit).

  • By far the best explanations for dummies like me. Thanks!
    – klewis
    Aug 8 '19 at 2:45

Here are some details. To damage, you must hit. To hit, you must understand THAC0 (To Hit Armor Class 0).

THAC0 is a value defined by your class (fighters have a lower THAC0 than mages).

When you attack, you throw a d20 and you subtract the value from your THAC0 to find the minimum AC value you hit.

Example: my fighter has a THAC0 of 16. If I throw a 16 on my d20, I would hit anything from AC 0 going up (remember, in AD&D 2nd Edition the lower the AC the better).

If I roll a 20, then I could hit an AC of -4.

After this, the damages work as answered in Fabian's post, with dice and strength modifiers. Also, some magic weapons have damage and THAC0 bonuses.

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    Thac0 is one reason I will stay far far away from 2nd ed. It's just a really rather unintuitive concept. Jan 19 '11 at 22:23
  • @aurevoir interesting! (a propos of the edit summary). To be honest, it's the other way I had never heard of. Not sure what I think of it, I guess I'll have to try to see how I like it!
    – Fractal
    Apr 24 '17 at 22:02

All factors that can effect the melee damage you see in the console:

  • Weapon base damage (additional damages like +2 acid will get their own line in the console)
  • Strength ability bonus
  • Weapon prociency
  • Resistances of the enemy being hit (native or spell effects)
  • Spell effects that improve damage (like Luck or Tenser's Transformation)
  • Critical hit
  • Backstab multiplier
  • Racial bonuses (with some race fix mod; vanilla does not implement these)

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