D&D 5E Armor Class Calculator
Calculate your character's Armor Class (AC) for Dungeons & Dragons 5th Edition. This tool helps determine how difficult it is for enemies to hit your character in combat.
D&D 5E Armor Class Calculator
Calculate D&D 5th edition armor class.
What Is Armor Class in D&D 5E?
Armor Class (AC) in D&D 5E represents how difficult a character is to hit with an attack. It is the target number that an enemy must roll on a d20 to successfully land a blow and deal damage.
Why Armor Class Determines Survival
High AC preserves Hit Points (HP), while low AC leads to rapid unconsciousness. When an enemy rolls an attack, they must meet or beat your AC. Due to the Bounded Accuracy design philosophy of 5th Edition, numbers stay relatively flat (usually 10–20), making every +1 to AC a significant 5% increase in survivability.
Important Note
AC does not protect against Saving Throws (like a Fireball) or Grapples; it only applies to weapon attacks and spells that require an attack roll.
Key Components of Armor Class
Calculating AC requires summing several modifiers. Armor Type determines the Base AC and limits how much of your Dexterity modifier you can add.
Armor Types and Limits
| Type | Base AC | Dex Cap | Stealth Disadvantage? |
|---|---|---|---|
| Light Armor | 11 + Dex | None | No |
| Medium Armor | Base + Dex (Max +2) | +2 | Varies |
| Heavy Armor | Set Value | 0 | Yes |
Dexterity and Shield Bonuses
Your Dexterity Modifier represents your ability to dodge. Shields are a separate equipment slot granting a flat +2 AC. Other bonuses include Cover (Half Cover +2, Three-Quarters +5) and class features like the "Defense" Fighting Style (+1).
Pro Tip: The Breakpoint
When your Dexterity modifier reaches +4 or +5, Light Armor (like Studded Leather) often outperforms Medium Armor because Medium Armor ignores stats above +2.
How the Armor Class Calculation Works
The Armor Class Calculation is the sum of Base Armor Value + Dexterity Modifier + Shield Bonus + Magic Bonus + Cover Bonus.
AC = Base Armor + Dex (Capped) + Shield + Magic + Cover
Calculation Steps:
- Identify Base AC (from armor or 10 for unarmored).
- Apply Dex Mod (Check armor type limits like Max +2).
- Add Shield Bonus (+2 if equipped).
- Add Misc Bonuses (Feats, Spells like Shield of Faith).
- Add Situational Cover.
Worked Example
Level 1 Fighter: Wears Chain Mail (Heavy, Base 16). Dex Mod is +2 (Ignored in Heavy). Uses a Shield (+2).
- Total AC = 16 (Base) + 0 (Dex) + 2 (Shield) = 18.
Applying Armor Class Rules Correctly
Calculating AC is easy, but applying Stacking Rules is where errors occur. You cannot wear two sets of armor, but magic items and shields generally do stack.
Unarmored Defense Explained
Unarmored Defense (Monk/Barbarian/Sorcerer) replaces the standard "Base 10 + Dex" calculation. It does not stack with worn armor.
- Monk: 10 + Dex + Wis.
- Barbarian: 10 + Dex + Con.
- Natural Armor (Lizardfolk): 13 + Dex (Cannot wear armor).
Rules Lawyer Callout
Mage Armor + Shield: Mage Armor sets Base AC to 13 + Dex. It does not stack with physical armor. However, it does stack with a shield, making it a powerful combo for Druids or Sorcerers.
Interpreting Your Armor Class Score
Understanding your Armor Class in context of combat probabilities (Hit Chance) helps you gauge your actual risk.
AC Ranges and Combat Effectiveness
Band 1: Extremely Low (AC 8–10)
Meaning: You will be hit by almost every attack. A standard Goblin (+4 to hit) hits you 85%–95% of the time. Action: Rely on cover immediately.
Band 2: Fragile (AC 11–13)
Meaning: Standard for unarmored casters. Common minions hit you 50% of the time. Action: Prioritize defensive spells like Shield or Mage Armor.
Band 3: Average (AC 14–16)
Meaning: Baseline survivability for frontline martial classes. Enemies need average rolls to hit. Action: Safe for skirmishes, but watch for Advantage.
Band 4: Resilient (AC 17–19)
Meaning: High-level tank territory. Weak enemies (low CR) cannot hit you without a Natural 20 (5% chance). Action: Absorb aggro to protect allies.
Band 5: Fortress (AC 20–25)
Meaning: Nearly untouchable by standard monsters. Requires optimized heavy armor or high-level Monks. Boss monsters still need a 12+ to hit. Action: You are immune to fodder; focus on battlefield control.
Armor Class Comparisons
Comparing Armor Types helps decide where to invest gold and Ability Score Improvements (ASIs).
Cost vs. Benefit Analysis
| Item | Base AC | At Dex +0 | At Dex +2 | At Dex +5 |
|---|---|---|---|---|
| Studded Leather (Light) | 12 | 12 | 14 | 17 |
| Scale Mail (Medium) | 14 | 14 | 16 | 16 (Capped) |
| Chain Mail (Heavy) | 16 | 16 | 16 | 16 |
Conclusion: If you plan to max out Dexterity (+5), Light Armor eventually surpasses Medium Armor. Heavy Armor is consistent but expensive and slow.
Shield Value
A shield provides a flat +2 AC to any armor type. This is equivalent to a 10% increase in survivability against average monsters, making it the single best defensive investment for most classes.
Factors Affecting Armor Class
Your AC fluctuates during combat due to Temporary Bonuses and Conditions.
Temporary Bonuses and Penalties
- Shield of Faith / Haste: +2 AC (Stacks with armor).
- Dodge Action: Attackers have Disadvantage (Statistically better than -2 AC).
- Prone Condition: -2 AC vs ranged, +2 AC vs melee. However, melee attackers get Advantage, so you take more hits overall.
- Reckless Attack (Barbarian): Grants Advantage to enemies, effectively negating your AC boost from Rage (+2 AC) for the sake of offense.
Character Build Scenarios
Optimizing Armor Class depends on your Class and role.
The Heavy Armor Tank (Level 1 Paladin)
Build: Chain Mail (16) + Shield (+2) + Fighting Style (+1) = 19 AC. Extremely hard to hit at low levels.
The Agile Rogue (Level 4 Wood Elf)
Build: Studded Leather (12) + Dex (+5) = 17 AC. Matches heavy armor without movement penalties.
The Unarmored Monk (Level 6)
Build: 10 + Dex (+3) + Wis (+3) = 16 AC. Can reach 20 AC with magic items, keeping hands free for Stunning Strike.
Armor Class Calculation Limits
Avoid Common Mistakes that result in illegal or overpowered AC values.
Common Mistakes
- Double Dipping: Adding Dex to AC when using a spell that sets AC (e.g., Barkskin).
- Stacking Armor: Wearing a Breastplate *and* Ring of Protection is fine, but wearing Plate *and* Leather is not allowed.
- Ignoring Caps: Adding +3 Dex to Medium Armor (Max is +2).
Limitation: AC does not stop Magic Missiles, which hit automatically. Always have a contingency plan for auto-hit spells.
Frequently Asked Questions About Armor Class
Official Rules & References
Content derived from Official Rules published by Wizards of the Coast.
- Player’s Handbook (5th Edition): Chapter 1 (Step-by-Step Characters) and Chapter 5 (Equipment). Primary source for Armor tables and class features.
- System Reference Document 5.1 (SRD): Open-source reference for core rules available online.
- Sage Advice Compendium: Official clarifications on rules interactions (e.g., Shield + Mage Armor stacking).
Disclaimer: D&D is a game of imagination. While this calculator follows RAW (Rules As Written), specific campaigns may have unique items or house rules. Always verify with your Dungeon Master.
About the Author
Kumaravel Madhavan
Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.