Armor Rules and Types in D&D

Armor class (AC) is one of the central defensive statistics in Dungeons & Dragons, determining how difficult a character or creature is to hit in combat. The armor system divides protective equipment into three categories — light, medium, and heavy — each with distinct mechanical properties, proficiency requirements, and interactions with ability scores. Understanding how armor type selection affects both AC calculation and character mobility is foundational to D&D character creation and combat viability.

Definition and scope

In D&D 5th Edition, armor is a category of equipment that sets or modifies a character's armor class, the numerical threshold an attacker must meet or exceed on an attack roll to deal damage. The core rules, published by Wizards of the Coast in the Player's Handbook, define armor class as the baseline defensive rating derived from the type of armor worn, relevant ability score modifiers, and any applicable bonuses from shields, spells, or class features.

Armor operates within the broader equipment and weapons rules framework. A character without armor still has an AC — typically 10 plus their Dexterity modifier — but armored characters replace that baseline with the formula specific to the armor type worn. Shields provide a flat +2 AC bonus and stack with any armor category.

Proficiency is the gating mechanism. Characters lacking proficiency in a worn armor type suffer disadvantage on all ability checks, saving throws, and attack rolls, and cannot cast spells. Proficiency is granted by character class, and in some cases by backgrounds and feats such as the Moderately Armored feat, which grants proficiency in medium armor and shields.

How it works

The three armor categories function as follows:

1. Light Armor — AC equals the armor's base value plus the wearer's full Dexterity modifier. The three light armors in the standard rules are:
2. Padded (11 + Dex modifier, disadvantage on Stealth)
3. Leather (11 + Dex modifier)

4. Studded Leather (12 + Dex modifier)

5. Medium Armor — AC equals the armor's base value plus the wearer's Dexterity modifier, capped at +2. Medium armors include:

6. Hide (12 + Dex, max +2)
7. Chain Shirt (13 + Dex, max +2)
8. Scale Mail (14 + Dex, max +2; disadvantage on Stealth)
9. Breastplate (14 + Dex, max +2)

10. Half Plate (15 + Dex, max +2; disadvantage on Stealth)

11. Heavy Armor — AC is a fixed value with no Dexterity modifier applied. Heavy armors include:

12. Ring Mail (14)
13. Chain Mail (16; requires Strength 13)
14. Splint (17; requires Strength 15)
15. Plate (18; requires Strength 15; disadvantage on Stealth)

Heavy armor wearers with a Dexterity modifier below 0 do not subtract that penalty from AC, but also gain nothing from a high modifier — the value is fixed.

The Strength requirement on heavy armor imposes a movement speed penalty of 10 feet if the wearer's Strength score falls below the listed threshold. This interacts directly with movement and positioning rules and is a critical consideration when building characters around heavy armor.

The Natural Armor and Unarmored Defense features represent a separate category. The Barbarian's Unarmored Defense calculates AC as 10 + Dexterity modifier + Constitution modifier. The Monk's version uses 10 + Dexterity modifier + Wisdom modifier. These features do not stack with worn armor but do stack with shields (Barbarian only, per the Player's Handbook).

Common scenarios

Rogues and Dexterity-focused builds consistently choose Studded Leather, achieving a maximum AC of 17 with a +5 Dexterity modifier, while preserving full stealth and hiding capability and avoiding proficiency requirements for heavier categories.

Clerics and Druids navigate the medium-versus-heavy distinction based on subclass. Life Clerics and War Clerics gain heavy armor proficiency from their subclass, pushing them toward Plate for a flat AC of 18. Moon Druids are restricted by the Druid class rule that prohibits metal armor regardless of proficiency source.

Multiclass combinations create armor proficiency interactions that require careful attention. A Fighter 1 / Wizard X multiclass gains proficiency in all armor and shields from the Fighter level. The multiclassing rules in the Player's Handbook specify that multiclass characters gain the armor proficiencies listed in the multiclassing proficiency table — not the full class proficiencies — which is a common source of rules confusion.

Magic armor modifies the base AC of the underlying armor type. A +1 Chain Mail, for example, has AC 17 rather than 16. Magic armor interactions are detailed within the magic items rules.

Decision boundaries

The central tradeoff between medium and heavy armor is AC ceiling versus Dexterity dependency. A character with a Dexterity modifier of +2 wearing Half Plate reaches AC 17 — identical to the ceiling achievable with Studded Leather for a Dexterity-maxed character. Plate armor's fixed AC 18 surpasses any unenchanted light or medium option, but requires Strength 15 and 1,500 gold pieces (per the Player's Handbook equipment table).

The light versus medium decision for Dexterity builds pivots on the +2 cap. Characters with a Dexterity modifier of +3 or higher lose advantage from medium armor — their Dexterity exceeds what medium armor permits, making light armor superior unless the medium option provides a higher base AC that compensates (e.g., Half Plate at 15 base versus Studded Leather at 12 base).

For a full structural overview of how defense mechanics integrate with the D&D ruleset, see the D&D core rules overview. Armor interacts heavily with saving throws, conditions, and broader combat rules — particularly in scenarios involving flanking and cover, where positional bonuses can modify effective AC without changing the armor itself. The recreational context for these mechanics is addressed at how recreation works: conceptual overview, situating tabletop play within its broader social and game-design context. The full site index is accessible at dndrules.com.

References

• Wizards of the Coast — Player's Handbook (5th Edition) — Primary source for armor categories, AC formulas, proficiency rules, Strength requirements, and equipment costs.
• Wizards of the Coast — Dungeon Master's Guide (5th Edition) — Covers magic armor variants and their AC modifications.
• D&D Beyond — Equipment Rules Reference — Official digital index of armor types, costs, weights, and properties as published by Wizards of the Coast.
• Wizards of the Coast — Systems Reference Document 5.1 — Open-license publication of core armor rules, including AC calculation formulas and proficiency mechanics.