B/X D&D TARGET NUMBERS
This summary changes B/X D&D rules to just use a d20 for almost all rolls. Classes are limited to Cleric, Fighter, Magic-User, and Thief. Dwarf and halfling are Fighters by default; Elf are treated as a Fighter/Magic-Users multiclass.
BASIC RULE
* Roll 1d20 and add any and all modifiers.
* If the modified total is equal to or greater than the target number, the character’s effort succeeds.
ABILITIES
* Strength (STR): Physical prowess, melee weapons.
* Dexterity (DEX): Agility, reflexes, ranged weapons.
* Constitution (CON): Health, fortitude, concentration.
* Intelligence (INT): Knowledge, memory, reason.
* Wisdom (WIS): Awareness, empathy, willpower.
* Charisma (CHA): Appeal, communication, leadership.
ABILITY CHECK TARGET NUMBERS
* 19 … Ability Score 1 (or -4 modifier)
* 18 … Ability Score 2 to 3 (or -3 modifier)
* 17 … Ability Score 4 to 5 (or -2 modifier)
* 16 … Ability Score 6 to 8 (or -1 modifier)
* 15 … Ability Score 9 to 12 (no modifier)
* 14 … Ability Score 13 to 15 (or +1 modifier)
* 13 … Ability Score 16 to 17 (or +2 modifier)
* 12 … Ability Score 18 to 19 (or +3 modifier)
* 11 … Ability Score 20 to 21 (or +4 modifier)
* 10 … Ability Score 22 to 23 (or +5 modifier)
OPPOSED CHECK ROLL: Both roll d20 and add modifiers. Highest total wins. Re-roll ties.
SKILL CHECK TARGET NUMBERS
* 17 … 1-in-6 chance
* 13 … 2-in-6 chance
* 10 … 3-in-6 chance
* 7 … 4-in-6 chance
* 3 … 5-in-6 chance
* 1 … 6-in-6 chance
PERCENTAGE SKILL CHECK TARGET NUMBERS
* 20 … 0% to 4%
* 19 … 5% to 9%
* 18 … 10% to 14%
* 17 … 15% to 19%
* 16 … 20% to 24%
* 15 … 25% to 29%
* 14 … 30% to 34%
* 13 … 35% to 39%
* 12 … 40% to 44%
* 11 … 45% to 49%
* 10 … 50% to 54%
* 9 … 55% to 59%
* 8 … 60% to 64%
* 7 … 65% to 69%
* 6 … 70% to 74%
* 5 … 75% to 79%
* 4 … 80% to 84%
* 3 … 85% to 89%
* 2 … 90% to 94%
* 1 … 95% to 100%
HOUSE RULE: ADVANTAGES (+3 modifier each)
Each distinct advantage grants a +3 bonus to the roll.
* Relevant training, experience, or exceptional natural talent.
* Superior tools, equipment, or resources.
* Careful preparation, planning, or useful information.
* Assistance from capable allies.
* Favorable environmental conditions or positioning.
* Familiarity with the task, location, or opposition.
* Surprise, exploited weaknesses, or tactical advantages.
* Adequate time and freedom from distractions.
* Favorable social circumstances, reputation, or authority.
HOUSE RULE: HINDRANCES (-3 modifier each)
Each distinct hindrance imposes a -3 penalty to the roll.
* Inexperience or unfamiliarity with the task.
* Wounds, exhaustion, emotional distress, or other impairments.
* Poor, damaged, or inappropriate equipment.
* Hostile environmental conditions or unfavorable positioning.
* Time pressure, distractions, or divided attention.
* Active opposition, interference, or enemy countermeasures.
* Insufficient resources, assistance, or information.
* Unusual complexity, demanding requirements, or conflicting objectives.
* Unfavorable social circumstances, distrust, or hostility.
Advantages and hindrances are cumulative, but multiple factors arising from the same underlying circumstance count as a single modifier. For example, darkness, heavy fog, and smoke might collectively impose one -2 hindrance for poor visibility, rather than three separate -2 penalties.
SAVING THROW TARGET NUMBERS
Save vs. Death Ray or Poison
* 14 … Normal Human
* 13 … Magic-User 1 to 5, Thief 1 to 4
* 12 … Fighter 1 to 3, Thief 5 to 8
* 11 … Cleric 1 to 4, Magic-User 6 to 10
* 10 … Fighter 4 to 6, Thief 9 to 12
* 9 … Cleric 5 to 8
* 8 … Fighter 7 to 9, Magic-User 11 to 15, Thief 13 to 16
* 6 … Cleric 9 to 12, Fighter 10 to 12
* 4 … Fighter 13 to 15
* 3 … Cleric 13 to 16
Save vs. Magic Wands
* 15 … Normal Human
* 14 … Magic-User 1 to 5, Thief 1 to 4
* 13 … Fighter 1 to 3, Thief 5 to 8
* 12 … Cleric 1 to 4, Magic-User 6 to 10
* 11 … Fighter 4 to 6, Thief 9 to 12
* 10 … Cleric 5 to 8
* 9 … Fighter 7 to 9, Magic-User 11 to 15, Thief 13 to 16
* 7 … Cleric 9 to 12, Fighter 10 to 12
* 5 … Cleric 13 to 16, Fighter 13 to 15
Save vs. Paralysis or Turn to Stone
* 16 … Normal Human
* 14 … Cleric 1 to 4, Fighter 1 to 3
* 13 … Magic-User 1 to 5, Thief 1 to 4
* 12 … Cleric 5 to 8, Fighter 4 to 6
* 11 … Magic-User 6 to 10, Thief 5 to 8
* 10 … Fighter 7 to 9, Cleric 9 to 12
* 9 … Thief 9 to 12, Fighter 10 to 12
* 8 … Magic-User 11 to 15
* 7 … Cleric 13 to 16, Thief 13 to 16
* 6 … Fighter 13 to 15
Save vs. Dragon Breath
* 17 … Normal Human
* 16 … Cleric 1 to 4, Magic-User 1 to 5, Thief 1 to 4
* 15 … Fighter 1 to 3
* 14 … Cleric 5 to 8, Magic-User 6 to 10, Thief 5 to 8
* 13 … Fighter 4 to 6
* 12 … Thief 9 to 12
* 11 … Cleric 9 to 12, Magic-User 11 to 15
* 10 … Fighter 7 to 9, Thief 13 to 16
* 8 … Cleric 13 to 16, Fighter 10 to 12
* 5 … Fighter 13 to 15
Save vs. Staves or Spells
* 18 … Normal Human
* 16 … Fighter 1 to 3
* 15 … Cleric 1 to 4, Magic-User 1 to 5, Thief 1 to 4
* 14 … Fighter 4 to 6
* 13 … Thief 5 to 8
* 12 … Cleric 5 to 8, Fighter 7 to 9
* 12 … Magic-User 6 to 10
* 10 … Fighter 10 to 12, Thief 9 to 12
* 9 … Cleric 9 to 12
* 8 … Fighter 13 to 15, Magic-User 11 to 15, Thief 13 to 16
* 7 … Cleric 13 to 16
SAVING THROW MODIFIERS
Versus any magical effects:
* -4: Wisdom score 1
* -3: Wisdom score 2 to 3
* -2: Wisdom score 4 to 5
* -1: Wisdom score 6 to 8
* +0: Wisdom score 9 to 12
* +1: Wisdom score 13 to 15
* +2: Wisdom score 16 to 17
* +3: Wisdom score 18 to 19
* +4: Wisdom score 20 to 21
* +5: Wisdom score 22 to 23
Species/Racial Bonuses:
* +4: Dwarf or halfling vs. death ray, poison, magic wands, paralysis, turn to stone, staves, and spells.
* +2: Dwarf or halfling vs. dragon breath.
* +1: Elf vs. paralysis, turn to stone, staves, and spells.
SURPRISE (d20)
* 1 to 6: Surprised, cannot act during the first round of the encounter.
* 7 to 20: Not surprised.
INITIATIVE
* Each side rolls a d20 (not each individual character).
* Highest roll acts first that round; if tied, both act simultaneously.
* Individuals may act in any order in each combat sequence step.
* Side with the lower roll acts next.
* Initiative is rolled again each round.
COMBAT SEQUENCE
* 1. Morale: Check monster morale when required.
* 2. Movement: Move characters and creatures.
* 3. Missile attacks: Resolve ranged attacks and damage.
* 4. Spellcasting: Cast spells and resolve their effects.
* 5. Melee attacks: Resolve hand-to-hand attacks and damage.
* Other side repeats sequence on their turn.
ATTACK “TO-HIT” TARGET NUMBERS
* 10 … None (AC 9)
* 11 … Shield (AC 8)
* 12 … Light Armor (AC 7)
* 13 … Light Armor and Shield (AC 6)
* 14 … Medium Armor (AC 5)
* 15 … Medium Armor and Shield (AC 4)
* 16 … Heavy Armor (AC 3)
* 17 … Heavy Armor and Shield (AC 2)
* 18 … Extra Heavy Armor (AC 1)
* 19 … Extra Heavy Armor and Shield (AC 0)
ATTACK MODIFIERS TO d20 TOTAL
(Note: Natural 20 always hits, natural 1 always fails.)
Class Attack Bonus
* +0: Normal Human, Cleric or Thief 1 to 4, Magic-User 1 to 5
* +1: Fighter 1 to 3, Cleric or Thief 5 to 8, Magic-User 6 to 10
* +3: Fighter 4 to 6, Cleric or Thief 9 to 12, Magic-User 11 to 15
* +6: Fighter 7 to 9, Cleric or Thief 13 to 16
* +8: Fighter 10 to 12
* +9: Fighter 13 to 15
* +Hit Dice: Monsters
Ability Modifiers
* +Strength modifier (melee)
* +Dexterity modifier (missile/ranged)
Situation Modifiers
* +1: Missile/ranged short range.
* +0: Missile/ranged medium range.
* -1: Missile/ranged long range.
* -1 to -4: Target partially behind cover.
* Cannot hit: Target completely behind cover.
* +2: Opponent retreating, exhausted, or attacked from behind.
* +4: Thief attacking with backstab.
* +1 to +3: Attacking with magic weapon.
* +1: Halfling using a missile weapon.
* +1: Attacker subject of Bless spell.
* +1: Attacker subject of Blight spell.
* -1: Attacking target protected by Protection from Evil spell (when applicable).
* -4: Attacking without looking directly at an opponent (such as a medusa).
* +2: Opponent attacking someone who deliberately avoids looking at them.
* -2: Attacker nauseated or confused by a monster’s special ability
* Automatic hit: Attacking a paralyzed target
DAMAGE PER HIT
* 1: Unarmed Strike
* 1d4: Club, dagger, sling stone, torch.
* 1d6: Arrow, crossbow bolt, hand axe, mace, short sword, spear, war hammer.
* 1d8: Battle axe (two-handed), sword; also, flask or burning oil.
* 1d10: Greatsword (two-handed), Pole arm (two-handed).
DAMAGE MODIFIERS
* +Strength modifier (melee)
* +1 to +3: Damage from magic weapon.
MORALE CHECKS
* 20 … Morale 2
* 19 … Morale 3
* 18 … Morale 4
* 17 … Morale 5
* 14 … Morale 6
* 12 … Morale 7
* 8 … Morale 8
* 6 … Morale 9
* 3 … Morale 10
* 2 … Morale 11
* 1 … Morale 12
When to check morale:
* First casualty: When the first member of a group is killed.
* Half defeated: When half the group has been killed or otherwise incapacitated.
* On failure, side flees or surrenders.
* Retainers and hirelings: May make morale checks, influenced by loyalty and leader’s Charisma modifier.
TURNING UNDEAD (approximate)
* 9 … HD 1 undead (skeleton) turned
* 16 … HD 2 undead (zombie) turned
* 19 … HD 2 undead (ghoul) turned
* 22 … HD 3 undead (wight) turned, HD 1 undead (skeleton) destroyed
* 25 … HD 4 undead (wraith), HD 2 undead (zombie) destroyed
* 28 … HD 5 undead (mummy), HD 2 undead (ghoul) destroyed
* 31 … HD 6 undead (spectre), HD 3 undead (wight) destroyed
* 34 … HD 7 to 9 undead (vampire), HD 4 undead (wraith) destroyed
* 37 … HD 7 to 9 undead (vampire), HD 5 undead (mummy) destroyed
* 40 … HD 7 to 9 undead (vampire), HD 6 undead (spectre) destroyed
* 43 … HD 7 to 9 undead (vampire) destroyed
TURNING MODIFIERS
* +0: Cleric 1
* +4: Cleric 2
* +8: Cleric 3
* +12: Cleric 4
* +16: Cleric 5
* +20: Cleric 6
* +24: Cleric 7
* +28: Cleric 8
* +32: Cleric 9
* +36: Cleric 10
* +40: Cleric 11 or higher
On success, roll for total Hit Dice affected (d20):
* 1 … 2 HD turned or destroyed
* 2 … 3 HD turned or destroyed
* 3 … 4 HD turned or destroyed
* 6 … 5 HD turned or destroyed
* 8 … 6 HD turned or destroyed
* 12 … 7 HD turned or destroyed
* 14 … 8 HD turned or destroyed
* 17 … 9 HD turned or destroyed
* 18 … 10 HD turned or destroyed
* 19 … 11 HD turned or destroyed
* 20 … 12 HD turned or destroyed
Turning Notes:
* Undead with fewer Hit Dice are affected first.
* Turned undead leave the area if possible and avoid the cleric for a day.
* A failed turning attempt cannot be repeated against the same group during that encounter.
MONSTER REACTIONS (d20)
* 1 … Immediate attack
* 2 to 5 … Hostile, possible attack
* 6 to 16 … Uncertain, monster confused
* 17 to 19 … No attack, monster leaves or considers offers
* 20 … Enthusiastic friendship
Reaction Modifiers:
* +Charisma modifier
CREATURE INTELLIGENCE SCALE
* INT 0 or 1: Non-intelligent or intelligence not ratable
* INT 2 to 3: Animal intelligence
* INT 4 to 5: Semi-intelligent
* INT 6 to 8: Low intelligence
* INT 9 to 12: Average (human) intelligence
* INT 13 to 15: Very intelligent
* INT 16 to 17: Highly intelligent
* INT 18 to 19: Exceptionally intelligent
* INT 20 to 21: Genius-level intelligence
* INT 22 to 23: Supra-genius
* INT 24 or more: Godlike intelligence