Decoding Armor Class (AC) in Dungeons & Dragons 5th Edition: A Comprehensive Guide
Fast answer first. Then use the tabs or video for more detail.
- Watch the video explanation below for a faster overview.
- Game mechanics may change with updates or patches.
- Use this block to get the short answer without scrolling the whole page.
- Read the FAQ section if the article has one.
- Use the table of contents to jump straight to the detailed section you need.
- Watch the video first, then skim the article for specifics.
In Dungeons & Dragons 5th Edition (5e), your Armor Class (AC) represents how difficult you are to hit in combat. It’s a single number that encapsulates your defenses, encompassing armor, agility, and other protective measures. To determine your AC, you primarily rely on one of several base calculations determined by whether or not you’re wearing armor, and if so, what kind. Then, you may add bonuses from shields, magic items, class features, and other effects. This final number is what your enemies must meet or exceed on their attack rolls to successfully strike you. Let’s dive into the specifics.
Understanding Base AC Calculations
The foundation of your AC is determined by the armor you (or don’t) wear. Here’s a breakdown of the most common base AC calculations:
-
Unarmored: 10 + your Dexterity modifier. This is the default for characters not wearing armor, often used by classes like monks and barbarians who have features that enhance their unarmored defense.
-
Light Armor: The armor’s AC value + your Dexterity modifier. For example, leather armor has an AC of 11. Thus, in leather armor, your AC is 11 + your Dexterity modifier. Light armors are usually preferred by Rogues, Rangers, and other agile combatants.
-
Medium Armor: The armor’s AC value + your Dexterity modifier (maximum of +2). This is a crucial distinction. While you still benefit from Dexterity, the bonus is capped. For example, a breastplate has an AC of 14. Thus, with breastplate, your AC is 14 + your Dexterity modifier (to a maximum of +2).
-
Heavy Armor: The armor’s AC value. No Dexterity modifier is added. Heavy armor provides the highest base AC but sacrifices agility. For example, plate armor has an AC of 18.
-
Shield: A shield adds +2 to your AC, regardless of the armor you’re wearing (or not wearing). This is a straightforward and effective way to improve your defenses.
Adding Bonuses to Your Base AC
Once you’ve determined your base AC, you can add other bonuses to further enhance your defenses:
-
Shields: As mentioned, a shield provides a flat +2 bonus to your AC.
-
Magic Items: Many magic items provide bonuses to AC, either directly or indirectly. Magical armor might grant a +1, +2, or +3 bonus to your existing AC. Rings or cloaks of protection also grant AC and saving throw bonuses.
-
Class Features: Certain classes have features that improve AC. Barbarians can add their Constitution modifier to their AC when unarmored (in addition to Dexterity). Monks can add their Wisdom modifier to their AC when unarmored (in addition to Dexterity).
-
Racial Traits: Some races offer natural armor or other defensive benefits that impact AC.
-
Spells: Spells like Shield of Faith or Barkskin can temporarily increase your AC.
-
Fighting Styles: Fighters can choose the Defense fighting style, which grants a +1 bonus to AC while wearing armor.
-
Cover: Being behind cover (half, three-quarters, or full) grants bonuses to AC and Dexterity saving throws.
An Example of AC Calculation
Let’s consider a 5th-level Fighter wearing plate armor (AC 18) and wielding a shield (+2 AC). They also have a Defense fighting style (+1 AC). Their total AC would be:
18 (Plate Armor) + 2 (Shield) + 1 (Defense Fighting Style) = 21
AC Beyond the Basics
It’s crucial to remember that AC is a static value. It doesn’t change unless an effect specifically modifies it. When an attacker makes an attack roll, they roll a d20, add their attack bonus (proficiency bonus + relevant ability score modifier), and compare the total to your AC. If the result meets or exceeds your AC, the attack hits.
Games Learning Society emphasizes the importance of understanding these mechanics for effective gameplay and strategic decision-making. Visit GamesLearningSociety.org to learn more.
Frequently Asked Questions (FAQs) About AC in 5e
1. What happens if I’m proficient in heavy armor but my Dexterity modifier is negative? Does heavy armor still prevent me from adding it?
Heavy armor prevents you from adding your Dexterity modifier. It does not prevent you from subtracting a negative Dexterity modifier. So, if your Dexterity modifier is -1, your AC is still just the base AC of the armor.
2. Can I stack multiple sources of AC calculation, such as wearing armor and using the Unarmored Defense feature?
No. You choose one base AC calculation method. You can’t stack them. You choose between using the armor’s AC or the unarmored AC calculation. However, you can still benefit from bonuses that apply on top of your chosen base AC.
3. If I have a magical bonus to AC from armor and a separate magical bonus to AC from a ring of protection, do those stack?
Yes, generally, bonuses from different sources stack unless they are explicitly stated not to. The magical bonus from armor and a ring of protection are from different sources and stack.
4. How does cover affect AC?
Half cover grants a +2 bonus to AC and Dexterity saving throws. Three-quarters cover grants a +5 bonus to AC and Dexterity saving throws. Full cover means you can’t be targeted directly.
5. Does proficiency affect AC?
No, proficiency itself does not directly add to AC. Proficiency in armor simply allows you to wear it without suffering penalties such as disadvantage on ability checks, saving throws, or attack rolls.
6. Is there a maximum AC in 5e?
There’s no hard-coded maximum AC, but practically speaking, it becomes increasingly difficult to raise AC beyond a certain point. The highest realistically achievable AC is in the upper 20s or low 30s with magic items and other buffs. While theoretical maximums exist in the 60s, these rely on extremely niche and improbable situations.
7. What is a good AC for a level 1 character?
A “good” AC at level 1 depends on your class and role. For a martial character, aiming for AC 16-18 is reasonable. A spellcaster might have lower AC, around 13-15, relying more on positioning and spells for defense.
8. How do temporary HP interact with AC?
Temporary hit points (THP) absorb damage before it affects your actual hit points. They do not affect your AC. They are like a buffer of additional health.
9. Can I use a shield while wielding a two-handed weapon?
No. You need a free hand to wield a shield. Therefore, you can’t use a two-handed weapon and a shield simultaneously.
10. Does the Shield spell stack with a physical shield?
Yes. The Shield spell provides a reaction-based bonus to AC, and it stacks with the AC bonus from a physical shield.
11. What is Natural Armor?
“Natural Armor” refers to a trait some monsters and a few races have that provides a base AC calculation similar to wearing armor, but without actually wearing armor. Some examples include a lizardfolk’s tough hide or a dragon’s scales.
12. How do I calculate AC for a character that multiclasses Barbarian and Monk?
If you multiclass as a Barbarian and Monk, you must choose either the Barbarian’s Unarmored Defense (10 + Dex + Con) or the Monk’s Unarmored Defense (10 + Dex + Wis). You cannot combine them.
13. What is the Armor Class of the Tarrasque?
The Tarrasque has a natural Armor Class of 25. This makes it one of the most difficult creatures to hit in the game!
14. How does the Haste spell affect AC?
The Haste spell grants the target a +2 bonus to AC. This bonus is in addition to whatever armor they may be wearing.
15. What is the difference between AC and Saving Throws?
Armor Class represents your ability to avoid physical attacks that directly target you. Saving throws represent your ability to resist other effects, such as spells, poisons, or traps. They are different defensive stats for different situations.