Armor Class

Player's Handbook, D&D Basic Rules, D&D Player's Basic Rules, Essentials Kit Rulebook

Your Armor Class (AC) represents how well your character avoids being wounded in battle. Things that contribute to your AC include the armor you wear, the shield you carry, and your Dexterity modifier. Not all characters wear armor or carry shields, however.

Without armor or a shield, your character’s AC equals 10 + his or her Dexterity modifier. If your character wears armor, carries a shield, or both, calculate your AC using the rules in chapter 5. Record your AC on your character sheet.

Your character needs to be proficient with armor and shields to wear and use them effectively, and your armor and shield proficiencies are determined by your class. There are drawbacks to wearing armor or carrying a shield if you lack the required proficiency, as explained in chapter 5.

Some spells and class features give you a different way to calculate your AC. If you have multiple features that give you different ways to calculate your AC, you choose which one to use.