D&D 5e Armor Class Calculator
Choose your armor or defense formula, add modifiers, and calculate your total AC instantly.
What Is Armor Class?
Armor Class (AC) is the number an attacker must meet or exceed on an attack roll to hit your character in Dungeons & Dragons 5e. A higher AC generally means you are harder to hit. AC comes from armor, Dexterity, shields, class features, spells, and situational bonuses like cover.
How This Armor Class Calculator Works
This calculator applies the most common 5e AC formulas and combines them with your modifiers. It is designed to be fast during character creation and useful during play when conditions change.
- Select an armor type or defense formula.
- Enter your Dexterity modifier.
- Add a secondary modifier for Barbarian (Con) or Monk (Wis), if needed.
- Apply shield, cover, and miscellaneous bonuses.
- Click Calculate AC to get your final total and a breakdown.
AC Rules by Armor Category
Light Armor
Light armor uses your full Dexterity modifier. This is ideal for high-Dex characters such as Rogues and many Rangers.
Medium Armor
Medium armor limits Dexterity contribution to a maximum of +2. If your Dex modifier is +4, only +2 is counted for AC in medium armor.
Heavy Armor
Heavy armor does not add Dexterity to AC at all. It provides a fixed base AC and is typically best for Strength-based frontliners.
Special Class and Racial Formulas
Some builds do not rely on normal armor. Barbarian and Monk use unarmored defense formulas, and some ancestries or subclasses provide alternate base AC calculations.
Common Sources of Extra AC
- Shield: Usually +2 AC.
- Defense Fighting Style: +1 AC while wearing armor.
- Magic gear: +1/+2/+3 armor or shields.
- Spells: Shield, Mage Armor, Haste, and others depending on class.
- Cover: +2 (half cover) or +5 (three-quarters cover).
Example Calculations
Example 1: Rogue in Studded Leather
Studded Leather is 12 + Dex. With a +4 Dexterity modifier and no other bonuses, AC is 16.
Example 2: Fighter in Plate with Shield
Plate is fixed at 18 AC. Add shield +2 for a total of 20. If the fighter also has half cover, AC becomes 22.
Example 3: Monk with Unarmored Defense
Monk AC is 10 + Dex + Wis. A monk with Dex +3 and Wis +4 has AC 17 before other bonuses.
Frequent AC Mistakes to Avoid
- Adding full Dex to medium armor instead of capping at +2.
- Adding Dex to heavy armor (it should not be included).
- Stacking formulas that do not stack (for example, using two different base AC formulas together).
- Forgetting temporary bonuses like cover or spell effects.
Build Smarter, Not Just Tankier
Armor Class matters a lot, but survivability also includes hit points, saving throws, resistances, movement, control, and positioning. A balanced character often performs better than one focused on AC alone. Use this calculator to compare gear and build choices quickly, then choose what fits your role and play style.
Final Thoughts
If you are planning a new character or optimizing an existing one, this armor class calculator gives you a reliable baseline in seconds. Keep it bookmarked for level-ups, new magic items, and tactical decisions at the table.