DnD Attack Rolls Explained

Attack rolls are the primary mechanical resolution tool for determining whether one combatant successfully strikes another in Dungeons & Dragons 5th Edition. This page covers the complete structure of the attack roll — how modifiers are assembled, how results are evaluated against Armor Class, and where the mechanic intersects with conditions, cover, and special rules. Understanding the attack roll is foundational to navigating the full DnD combat rules system.

Definition and scope

An attack roll is a d20 roll made by a player or Dungeon Master to determine whether an attack attempt hits its target. The result of the roll, plus any applicable modifiers, is compared against the target's Armor Class (AC). If the total meets or exceeds the AC, the attack hits and the attacker proceeds to roll damage. If it falls short, the attack misses and no damage is applied.

The attack roll applies across three primary categories of attacks: melee weapon attacks, ranged weapon attacks, and spell attacks. Each category follows the same core resolution structure — roll d20, add modifiers, compare to AC — but draws on different ability score modifiers and is subject to different situational rules. Spell attacks, for instance, use a spellcasting attack bonus derived from the caster's spellcasting ability modifier plus proficiency bonus, rather than Strength or Dexterity. The full breakdown of how spellcasting modifiers interact with attack rolls is detailed in the DnD spellcasting rules.

The scope of the attack roll mechanic is defined in the Player's Handbook (5th Edition, Chapter 9) and the Basic Rules published by Wizards of the Coast, which are freely available online.

How it works

The attack roll formula has 3 components:

1. d20 roll — A single twenty-sided die is rolled. A natural 20 is a critical hit regardless of modifiers; a natural 1 is an automatic miss regardless of modifiers.
2. Ability modifier — Melee attacks typically use the Strength modifier; ranged attacks typically use Dexterity. Finesse weapons allow either. The DnD ability scores and modifiers page details how these scores are calculated.
3. Proficiency bonus — Added when the attacker is proficient with the weapon or spell being used. Proficiency bonus scales from +2 at level 1 to +6 at level 17 and above, as defined in the Player's Handbook progression table.

The assembled total is compared against the target's AC. AC is determined by armor worn, Dexterity modifier (in most cases), and any active spells or features. Full AC calculation rules are covered under DnD armor rules.

A critical hit — achieved on a natural 20 — doubles the number of damage dice rolled, not the total damage. If a fighter with a longsword normally rolls 1d8 damage, a critical hit produces 2d8 before modifiers are added. Some class features, such as the Champion Fighter's Improved Critical, expand the critical hit range to 19–20.

Advantage and disadvantage directly modify how the d20 is rolled: advantage means rolling 2d20 and taking the higher result; disadvantage means rolling 2d20 and taking the lower. These conditions do not stack — a creature either has advantage, disadvantage, or neither, regardless of how many sources apply.

Common scenarios

Ranged attacks in melee range: A creature making a ranged attack while within 5 feet of a hostile creature rolls with disadvantage. This rule incentivizes positioning and is a frequent tactical consideration in combat.

Two-weapon fighting: When a character makes an attack with a light melee weapon in one hand and uses their bonus action to attack with a light melee weapon in the other, the second attack does not add the ability modifier to damage unless the character has the Two-Weapon Fighting style. Both attacks still require separate attack rolls. See DnD action types explained for how bonus actions interact with the attack sequence.

Attacks against hidden or unseen targets: Attacking a creature the attacker cannot see is made with disadvantage. Attacking while the attacker is hidden grants advantage. If both conditions apply simultaneously, they cancel out. The DnD stealth and hiding rules govern when a creature qualifies as hidden.

Cover: Targets behind half cover receive a +2 bonus to AC; those behind three-quarters cover receive a +5 bonus. Total cover renders a target untargetable by direct attacks. The DnD cover rules define how cover is assessed geometrically on a grid.

Grapple and shove: These are special melee attack actions that replace a standard attack with a contested ability check rather than a d20 attack roll against AC. DnD grappling rules cover the full resolution process, which uses Athletics versus Athletics or Acrobatics.

Decision boundaries

Several conditional rules determine when an attack roll is made versus when an alternative resolution applies:

• Saving throw vs. attack roll: Spells and effects either require an attack roll (the caster rolls against the target's AC) or impose a saving throw (the target rolls against a fixed DC). A fireball requires a Dexterity saving throw; an inflict wounds spell requires a melee spell attack roll. The DnD saving throws rules and DnD difficulty class rules cover the saving throw side of this boundary.
• Automatic hits and misses: Natural 1 always misses; natural 20 always hits. No modifier can override this. A +15 attack bonus does not convert a natural 1 into a hit.
• Immunity and resistance: A successful attack roll that deals damage is still subject to resistance (half damage) or immunity (no damage) based on damage type. These apply after the roll resolves, not before. Damage resolution mechanics are covered in DnD damage and hit points rules.
• Opportunity attacks: Moving out of a hostile creature's reach triggers an opportunity attack — a single melee attack using a reaction. DnD opportunity attacks rules define exactly when this reaction is triggered and when it can be avoided.

For a broader orientation to how attack rolls fit within the full structure of play, the how DnD works conceptual overview and the full rules index provide structured entry points to the complete ruleset.

References

• Wizards of the Coast — D&D Basic Rules, Chapter 9: Combat
• D&D Beyond — Player's Handbook, Chapter 9 (Attack Rolls)
• Wizards of the Coast — Official D&D 5th Edition Resources