Armor Class in 5e: How to Calculate AC, With Every Formula
Armor Class (AC) is the number an attack roll must meet or beat to hit you. Without armor it is 10 + your Dexterity modifier. Armor replaces that base: light armor adds your full Dex, medium adds up to +2, heavy adds none. A shield adds +2, and cover adds +2 or +5.
How do you calculate Armor Class in 5e?
Your AC is built in two steps. First pick one base formula: no armor, a suit of armor, or a class feature or spell that sets your base AC. Then add every bonus that applies: a shield, magic items, spells and cover. You can't combine two base formulas; a monk in Mage Armor uses one or the other, whichever is higher.
- No armor: 10 + Dexterity modifier.
- Light armor: armor value + full Dexterity modifier.
- Medium armor: armor value + Dexterity modifier, maximum +2.
- Heavy armor: flat armor value, no Dexterity.
- Shield: +2 on top of any of the above.
An attack hits if the d20 roll plus the attack bonus equals or beats your AC. The DnD character sheet keeps your AC next to your hit points so it's ready when the DM asks.
What AC does each type of armor give?
These are the 2024 Player's Handbook values, which match 2014 for AC. Prices, weights and stealth penalties are on the armor page.
| Armor | Type | AC formula | AC with Dex +2 | Strength needed |
|---|---|---|---|---|
| Padded / Leather | Light | 11 + Dex | 13 | – |
| Studded leather | Light | 12 + Dex | 14 | – |
| Hide | Medium | 12 + Dex (max 2) | 14 | – |
| Chain shirt | Medium | 13 + Dex (max 2) | 15 | – |
| Scale mail / Breastplate | Medium | 14 + Dex (max 2) | 16 | – |
| Half plate | Medium | 15 + Dex (max 2) | 17 | – |
| Ring mail | Heavy | 14 | 14 | – |
| Chain mail | Heavy | 16 | 16 | 13 |
| Splint | Heavy | 17 | 17 | 15 |
| Plate | Heavy | 18 | 18 | 15 |
| Shield | Shield | +2 | +2 | – |
If you wear heavy armor without the listed Strength, your Speed drops by 10 feet. Without proficiency in the armor you're wearing, you have disadvantage on Strength and Dexterity checks, saves and attack rolls, and you can't cast spells.
How does Unarmored Defense work?
Two classes get their own base formula, used only while wearing no armor:
- Barbarian: 10 + Dexterity modifier + Constitution modifier. A shield is allowed. With Dex 14, Con 16 and a shield, that's 10 + 2 + 3 + 2 = 17.
- Monk: 10 + Dexterity modifier + Wisdom modifier, with no armor and no shield. Dex 16 and Wis 16 gives 16 at level 1, rising as those scores climb.
Other features and spells set a base the same way: Mage Armor makes it 13 + Dex for 8 hours, and a Draconic Sorcerer's resilience sets 10 + Dex + Charisma in 2024 (13 + Dex in 2014). None of them stack with each other or with worn armor.
What bonuses add to AC?
- Shield (item): +2. You get the bonus from only one shield at a time.
- Shield (spell): +5 until the start of your next turn, cast as a Reaction after you're hit, which can turn that hit into a miss.
- Shield of Faith: +2 for up to 10 minutes, with Concentration.
- Defense fighting style: +1 while wearing armor.
- Magic armor and items: +1 to +3 armor or shields, Ring or Cloak of Protection (+1).
- Barkskin: not a bonus but a floor. In 2024 the target's AC becomes 17 if it was lower, for 1 hour with no Concentration; the 2014 version set a minimum of 16 and needed Concentration.
How does cover affect AC?
Cover is the bonus most players forget. It applies to attacks from the other side of the obstacle and also to Dexterity saving throws.
| Cover | Example | Bonus to AC and Dex saves |
|---|---|---|
| Half | Low wall, another creature, furniture | +2 |
| Three-quarters | Arrow slit, thick tree trunk | +5 |
| Total | Fully behind a solid wall | Can't be targeted directly |
The cover guide covers how to judge which level applies.
What is a good AC in 5e?
Each point of AC removes 5% of hits from a given attacker. This table shows how often an attacker hits different AC values (a natural 1 always misses and a natural 20 always hits).
| Attack bonus | AC 12 | AC 14 | AC 16 | AC 18 | AC 20 |
|---|---|---|---|---|---|
| +4 (goblin) | 65% | 55% | 45% | 35% | 25% |
| +5 (orc) | 70% | 60% | 50% | 40% | 30% |
| +7 | 80% | 70% | 60% | 50% | 40% |
As a rough guide for early levels: 12 to 13 is a squishy caster, 15 to 16 is a sturdy skirmisher, and 18 or more is a front-line tank. A level 1 fighter in chain mail with a shield sits at 18; once they afford plate, it's 20.
FAQ
How is AC calculated in 5e?
Start with one base formula: 10 + Dexterity modifier with no armor, or your armor's formula (for example chain mail is a flat 16). Then add bonuses such as +2 for a shield, magic items, spells and cover.
What is a good AC in 5e?
At level 1, 14 to 16 is solid and 18 is excellent. Plate armor and a shield give 20, which most low-level monsters hit only about 30 to 40% of the time.
Can you stack Unarmored Defense and Mage Armor?
No. Unarmored Defense, Mage Armor and wearing armor are all ways to set your base AC, and you can only use one at a time. Bonuses like a shield or the Shield spell do stack with whichever one you pick.
Does a shield work with Unarmored Defense?
A Barbarian keeps Unarmored Defense with a shield (10 + Dex + Con + 2). A Monk loses Unarmored Defense if they hold a shield, in both 2014 and 2024.
What happens if you wear armor without proficiency?
You have disadvantage on ability checks, saving throws and attack rolls that use Strength or Dexterity, and you can't cast spells. This is the same in 2014 and 2024.
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Contains content from the System Reference Document 5.1 and 5.2 by Wizards of the Coast LLC, used under the Creative Commons Attribution 4.0 International License.