PD2 Hit Chance

You

Attack rating (character screen) Defense (character screen) Character level

Attack

Block chance (character screen) You are

Ignore target's defense

More: −% and −per-hit target defense, bonus AR vs demons and undead

−% target defense +AR vs demons +AR vs undead AR % on your screenneeded only for +AR vs demons / undead −Monster defense per hitthe number on the item, e.g. 25 Hits already landed Blessed Aim hard pointsits passive: −1% target defense per point

Curses and auras on the monster

Skill levels, 0 = not used. The same curse or aura from two people doesn't stack.

Conviction Weaken Battle Cry Cloak of Shadows Attract Curse Mastery hard pointsadds to Attract Inner Sight

More: dodge, avoid, evade, weapon block, defense vs melee / missile

Dodge % (melee) Avoid % (missiles) Evade % (while moving) Weapon block % Weapon +Defense vs melee +Defense vs missile

The monster

Difficulty Game Players in game

Map or area Monster

Type Champion kind Its attack

Extra Strong Stone Skin It shoots a missile

Map modifiers and zones

Map: monsters have +% defense Map: +area levelmaps only Map: monsters have +% attack rating Desecrated zone (Hell, outside maps: level 85)

The numbers

Final values, after every bonus: the attacker's attack rating and level, the defender's defense and level.

Attacker's AR Attacker's level Defender's defense Defender's level

Chance to hit

–

roll 0hits when the roll (0–99) is below the chance99

Attack rating you need

How PD2 decides whether an attack hits

Every melee attack and every missile that can miss goes through one roll in ProjectDiablo.dll (0x10271740), called from PD2's own attack resolver (0x10270EB0) in place of the base game's roll. The steps, in order:

Target defense
The defender's defense (dexterity ÷ 4 plus armor, times the % bonuses), plus defense vs melee or vs missile. Ignore Target's Defense sets it to 0 against normal monsters, champions and minions at any level (there's no level condition); not against uniques, superuniques, bosses (every monster flagged as a boss in the game data: act bosses, ubers, map bosses and more), mercenaries or players. −% target defense is capped at 100 and halved against players, bosses, superuniques and mercenaries; your curses and auras (Conviction, Weaken, Battle Cry, Cloak of Shadows, Attract, Inner Sight) change the monster's defense itself.
Defense lost per hit
"−X to Monster Defense Per Hit" isn't part of the roll. Each hit that lands (at the start of the swing, after the block check) permanently lowers the monster's base defense by X, down to 0 (D2Game 0x6FCFA890, still used by PD2). Later rolls see the lower defense. Enter it with the number of hits already landed.
Attack rating
Your base AR (attack rating + 5 × dexterity − 35 + your class's bonus). +AR vs demons or undead is added here. Then all the % at once: attack rating %, the skill's attack bonus, weapon mastery (melee only) and % vs monster type. The character screen shows your AR with the same % applied, so for most attacks the screen number is the one used.
AR = base × (100 + %) ÷ 100
The ratio
PD2 multiplies by 111 where the base game used 100, so everyone hits a bit more often.
ratio = 111 × AR ÷ (AR + Defense)
Levels
chance = ratio × 2 × attacker level ÷ (attacker level + defender level)
Limits
Below 5 becomes 5. Up to 95 it stays as is. Above 95 the extra ratio only counts at 90/111, and the result stops at 100. So 100% is reachable; the base game stopped at 95.
excess = ratio − 95 × (aLvl + dLvl) ÷ (2 × aLvl) excess = excess × 90 ÷ 111 chance = 95 + excess × 2 × aLvl ÷ (aLvl + dLvl), at most 100
The roll
A number from 0 to 99 from PD2's own random generator; the attack hits when it's below the chance. Every division drops the remainder.
Block, dodge, avoid, evade
Only after a hit. Shield block first (your character-screen block, capped at 75; PD2 has no penalty for moving). Then weapon block (two-handed swords and two claws, capped at 75), then evade if you're walking or running (if you're moving with no evade, dodge and avoid aren't tried), then dodge for melee or avoid for missiles. On PvP maps these three are halved.

What's different from the base game

Ratio 111 instead of 100, and a soft cap from 95 up to a hard 100 instead of a flat 95.
Running players are rolled against like everyone else; the base game hit them automatically.
Missiles: most never roll at all. Only missiles whose data says they can miss (108 of 1,057) roll, using the skill's attack bonus plus throwing mastery, not the missile's own attack rating.
Weapon mastery: throwing mastery counts only when both the weapon and the skill are throwable; otherwise the melee mastery.
Smite and splash damage always hit. Leap Attack and Blade Sentinel count your AR% twice. Blade Shield rolls but can't be blocked.
Monsters: champions get +2 levels and +67 / 56 / 49% AR (Normal / Nightmare / Hell); uniques, superuniques and minions +3 levels; Extra Strong and Berserker add AR%; Fanatic is −70% defense. Monster AR also grows by 8/128 per player beyond the first in Nightmare and Hell.

Every mechanic, one by one

Open any of these to see exactly what it does, when it applies and its limits.

Developer reference

Addresses are virtual addresses in the shipped DLLs: D2Game.dll at 0x6FC20000, D2Common.dll at 0x6FD50000, ProjectDiablo.dll (PD) at 0x10000000. VERIFIED means the real code was run natively on generated inputs and matched this page's code exactly; READ means read from the disassembly; DATA means taken from PD2's .txt tables.

Call chain for a player's melee attack on a monster

Melee start (srvstfunc)	D2Game 0x6FC64BE5	calls the stock resolver 0x6FCFE5A0, which PD2 redirects (31 of 34 call sites, via wrapper PD 0x102EEDA0)
Resolver	PD 0x10270EB0	(defender, attacker, …): melee range PD 0x10270FF0 → hit roll → block chain; returns the hit flags
Hit roll	PD 0x10271740	levels (stat 12), defense (#10672 + stat 33/32), player AR (#10621), target adjustments, AR %, chance, roll
Target adjustments	PD 0x10271620	stat 115 ITD, stat 116 −% target defense; boss test D2Common #10064 (PD 0x10278580), hireling test #11104 (PD 0x102784F0)
Weapon mastery	PD 0x102727D0	stat 342 melee, 345 throwing
AR vs monster type	PD 0x10279790 / 0x102EFB10	stat 179 entries matched against MonType
AR %	PD 0x102CE840	double: bonus = AR × pct ÷ 100, truncated, clamped to int32
Chance	PD 0x10271470	111 ratio, level factor, 5 floor, soft cap above 95, 100 cap
Random roll	PD 0x102C5D10	PD2's own generator on the attacker's seed; hit if value % 100 < chance
Block / dodge / avoid / evade	PD 0x1026FB60 → 0x1026FCF0	defender's seed; any success clears the hit bit (PD 0x10270FB9)
Damage store	D2Game 0x6FCFDDE0	runs only with the hit bit set; applies −defense per hit (0x6FCFD450 → 0x6FCFA890)

Every factor

How this was checked

The whole hit roll (PD 0x10271740 with its helpers) ran natively in a 32-bit harness that loads the real DLL images at their base addresses: 30,000 random cases, 0 mismatches against this page's code. The chance function alone: 8,180 cases, 0 mismatches.
The block / dodge / avoid / evade chain: 8,000 cases, 0 mismatches. Ignore Target Defense: 106 cases incl. higher-level monsters, champions and minions.
Monster defense and AR scaling come from D2Common #11089 (verified earlier) with MonStats / MonLvl; champion and unique modifiers are read from the MonUMod handlers.

Data: PD2 data.zip (MonStats, MonStats2, MonLvl, Levels, MonUMod, MonType, SuperUniques, Skills, Missiles, ItemStatCost). The calculator's code is the same module the tests run (window.PD2Hit).

Attack rating you need

How PD2 decides whether an attack hits

Target defense

Defense lost per hit

Attack rating

The ratio

Levels

Limits

The roll

Block, dodge, avoid, evade

What's different from the base game

Every mechanic, one by one

Developer reference

Call chain for a player's melee attack on a monster

Every factor

How this was checked