Armor Class Calculation 5e

In Dungeons & Dragons 5th Edition, your Armor Class (AC) is a crucial statistic that determines how difficult you are to hit in combat. A higher AC means enemies will have a tougher time landing successful attacks, making you more resilient on the battlefield. Understanding how AC is calculated is fundamental for both new and veteran players, allowing for optimal character building and tactical decision-making.

The Basics of Armor Class

At its core, your Armor Class is a numerical representation of your defensive capabilities. When an enemy attacks you, they roll a d20 and add their attack bonus. If the total equals or exceeds your AC, the attack hits. Otherwise, it misses.

Formula Overview

Unlike previous editions, 5e streamlines AC calculation significantly. You typically choose one primary method for determining your base AC, and then add certain modifiers. You cannot stack multiple base AC calculations (e.g., you can't use both Light Armor AC and Monk's Unarmored Defense simultaneously).

Dexterity Modifier Explained

Your Dexterity (Dex) modifier is a key component for many AC calculations. It represents your agility, reflexes, and ability to dodge or move out of the way. The higher your Dex modifier, the better your chances of avoiding blows, especially when wearing lighter armor or no armor at all.

Armor Types and Their AC

Unarmored AC

Characters without armor rely solely on their natural agility or specialized training.

• Standard Unarmored: 10 + your Dexterity modifier. This is the default for most creatures and characters not wearing armor.
• Monk Unarmored Defense: 10 + your Dexterity modifier + your Wisdom modifier. Monks, through their disciplined training, can channel their inner focus into defense.
• Barbarian Unarmored Defense: 10 + your Dexterity modifier + your Constitution modifier. Barbarians' raw toughness and primal instincts allow them to shrug off blows.

Light Armor

Light armor offers minimal protection but allows for maximum mobility.

• Formula: The armor's base AC + your Dexterity modifier. Since light armor doesn't impede movement, your full Dexterity bonus applies.
• Examples:
  • Padded Armor: 11 + Dex modifier
  • Leather Armor: 11 + Dex modifier
  • Studded Leather Armor: 12 + Dex modifier

Medium Armor

Medium armor provides more protection than light armor but restricts movement slightly.

• Formula: The armor's base AC + your Dexterity modifier (maximum of +2). Even if your Dex modifier is +3 or higher, you can only add +2 to your AC from medium armor.
• Examples:
  • Hide Armor: 12 + Dex modifier (max +2)
  • Chain Shirt: 13 + Dex modifier (max +2)
  • Scale Mail: 14 + Dex modifier (max +2)
  • Breastplate: 14 + Dex modifier (max +2)
  • Half Plate: 15 + Dex modifier (max +2)

Heavy Armor

Heavy armor offers the best physical protection but is cumbersome and requires significant strength.

• Formula: The armor's base AC. Your Dexterity modifier does not apply to heavy armor AC.
• Examples:
  • Ring Mail: 14
  • Chain Mail: 16
  • Splint Armor: 17
  • Plate Armor: 18

Natural Armor

Some creatures and races possess natural armor, such as a dragon's scales or a Tortle's shell.

• Formula: Usually a fixed base AC, sometimes with a Dexterity modifier added. For example, a Tortle has a base AC of 17, and some monsters might have "13 + Dex modifier."

Adding to Your AC

Beyond your primary armor type, several other factors can increase your AC.

Shields

Equipping a shield provides a straightforward bonus.

• Bonus: A shield grants a +2 bonus to your AC.

Magical Bonuses

Magical items are a common way to enhance your defenses.

• Magic Armor/Shields: A +1, +2, or +3 bonus to AC, depending on the item's rarity. This bonus is added to the armor's base AC.
• Rings of Protection/Cloaks of Protection: These items typically grant a +1 bonus to AC (and saving throws) when worn.

Spells and Class Features

Many spells and class abilities offer temporary or permanent AC buffs.

• Shield of Faith (Spell): Grants a +2 AC bonus for up to 10 minutes (concentration).
• Haste (Spell): Grants a +2 AC bonus for up to 1 minute (concentration).
• Defensive Fighting Style (Fighter/Paladin): Grants a +1 bonus to AC when wearing armor.
• Warforged Integrated Protection (Racial Trait): Adds +1 to AC.
• Forge Domain Cleric Blessing of the Forge: Can imbue a weapon or armor with a +1 bonus.

Feats

Some feats can also contribute to your AC.

• Heavy Armor Master: While it doesn't directly increase AC, it reduces damage taken, effectively making you tougher.
• Defensive Duelist: Allows you to use your proficiency bonus as an AC bonus against one melee attack when wielding a finesse weapon.

Important Considerations

• Combining AC Sources: Remember, you typically use only one base AC calculation (e.g., from armor, Unarmored Defense, or Natural Armor). Bonuses from shields, magic items, spells, and other features are then added on top of that base.
• Disadvantage on Stealth: Medium and Heavy armor types often impose disadvantage on Dexterity (Stealth) checks.
• Strength Requirements: Heavy armor can slow you down if you don't meet its minimum Strength score.
• Proficiency: You must be proficient with an armor type to gain its benefits. Wearing armor you aren't proficient in gives you disadvantage on ability checks, saving throws, and attack rolls, and you can't cast spells.

Mastering AC calculation is a key step in becoming a more effective D&D player. Whether you're a nimble rogue, a heavily armored paladin, or a wise monk, understanding your defenses will help you survive the many dangers of the multiverse.