D&D Armor Class (AC) Calculator
Calculate your D&D 5e Armor Class based on armor type, Dexterity modifier, shield, and magic bonuses.
Includes DEX cap rules for all armor types.
How Armor Class Works
Armor Class (AC) determines how hard your character is to hit. When an enemy attacks, they must roll equal to or higher than your AC on a d20 (plus their attack bonus).
DEX Modifier and Armor
Light armor lets you add your full DEX modifier. Medium armor caps your DEX bonus at +2. Heavy armor ignores your DEX modifier entirely.
Armor Types and Base AC
| Armor | Base AC | DEX Bonus | Category | Cost |
|---|---|---|---|---|
| No Armor | 10 | Full DEX | Unarmored | free |
| Padded | 11 | Full DEX | Light | 5 gp |
| Leather | 11 | Full DEX | Light | 10 gp |
| Studded Leather | 12 | Full DEX | Light | 45 gp |
| Hide | 12 | Max +2 | Medium | 10 gp |
| Chain Shirt | 13 | Max +2 | Medium | 50 gp |
| Scale Mail | 14 | Max +2 | Medium | 50 gp |
| Breastplate | 14 | Max +2 | Medium | 400 gp |
| Half Plate | 15 | Max +2 | Medium | 750 gp |
| Ring Mail | 14 | None | Heavy | 30 gp |
| Chain Mail | 16 | None | Heavy | 75 gp |
| Splint | 17 | None | Heavy | 200 gp |
| Plate | 18 | None | Heavy | 1,500 gp |
Shield
A shield grants +2 AC regardless of armor type. You must have one free hand to use a shield.
Magic Armor Bonus
A +1, +2, or +3 armor adds its bonus directly to the final AC value. A +1 Shield adds +1 on top of the normal shield +2 (total +3).
The two things a raw AC number will not tell you
First, proficiency. Wearing armor you are not proficient with gives you disadvantage on every attack roll, every ability check and every saving throw that uses Strength or Dexterity, and you cannot cast spells at all. A Wizard in Plate has AC 18 and is functionally useless. This calculator compares armors on AC alone, so read any “higher AC available” suggestion as “if your class can wear it.”
Second, Strength. Chain Mail needs Strength 13; Splint and Plate need Strength 15. Fall short and your speed drops by 10 feet, which in practice means you arrive at the fight a round late.
Unarmored Defense
Two classes replace the base 10 entirely. A Barbarian uses 10 + DEX + CON, a Monk uses 10 + DEX + WIS, and both can climb past Plate at high levels without ever buying armor. A Monk with DEX +5 and WIS +5 sits at AC 20. Neither can be modelled by picking an armor from the list above, so use the No Armor option and add your CON or WIS modifier by hand.
Draconic Sorcerers get 13 + DEX from Draconic Resilience, and a Bladesinging Wizard adds INT while the song is up. Mage Armor, the level 1 spell, sets the base to 13 + DEX for eight hours.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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