Determining AC 5e involves interpreting game text, math, and table values to correctly apply armor class in Dungeons Dragons 5th Edition. This guide walks through sources of AC, calculation patterns, and practical rulings so players and DMs can resolve combat quickly and consistently.
Below is a reference table that compares common AC determination approaches, including base values, modifiers, and special considerations for different character builds.
| Method | Base AC | Key Modifiers | Typical Use Case |
|---|---|---|---|
| Light Armor | 10 + Dexterity modifier | Dex cap, shield bonus | Rogues, Monks, Fighters |
| Medium Armor | Base varies by type | Dex cap, armor check penalty, stealth | Clerics, Paladins, Rangers |
| Heavy Armor | Fixed values (15–18) | No Dex bonus, sometimes disadvantage on stealth | Fighters, Wizards (armor focus) |
| Unarmored | 10 + Dexterity + Constitution | Class feature, no armor or shield required | Monks, some Druids |
| Shield Bonus | +2 | Active when wielding, lost if flat-footed | Universal, especially for squishy casters |
Calculating Base Armor Class
Base AC depends on the type of armor worn and whether a shield is used. Light armor ties AC to the Dexterity modifier, while medium and heavy armor provide fixed numbers with their own trade-offs. Unarmored calculations leverage class features such as Monk or Wild Shape rather than equipment.
Class Features and Races
Many classes offer alternative AC calculations, and some racial traits adjust these numbers. Unarmored monks rely on high Dexterity and Constitution for AC, while armored fighters may focus on Strength and Constitution instead.
Interpreting Rules Text
Official rules sometimes include exceptions or conditional language that affect how AC is determined. Features like Draconic Resilience or reactions such as Uncanny Dodge interact with the base number and must be applied in the correct order according to the rules timeline.
Common Modifiers and Interactions
Certain spells, magic items, and class abilities add flat bonuses, impose penalties, or change how Dexterity applies to AC. Understanding when a Dex modifier is capped, when it can apply, and which bonuses stack helps avoid mistakes at the table.
Optimizing AC for Your Build
Different characters prioritize AC for survivability, mobility, or role. Understanding your playstyle and campaign threats helps you choose armor, shields, and bonuses that fit your goals.
- Choose light armor and prioritize Dexterity for mobility and high AC cap.
- Select medium armor if you need consistent protection without Dexterity dependence.
- Use a shield when facing melee-heavy encounters, remembering the AC trade-off if flat-footed.
- Leverage class features and magic items to push AC into reliable survivability ranges.
- Balance AC with other defenses such as hit points and damage mitigation options.
FAQ
Reader questions
Do I add my Dexterity modifier to AC if I am wearing medium armor? It depends on the specific armor. Some medium armor allows you to add your Dexterity modifier up to a cap, while other types limit or remove that bonus. Always check the armor description in the Player’s Handbook. Can my AC ever exceed 20 in normal play?
Yes, AC can exceed 20 through a combination of high Dexterity, a shield, heavy armor, magic items, and class features. No hard cap exists in the rules, though very high AC is rare in practice.
Does cover still apply if my AC is extremely high?
Yes. Cover provides a separate mechanic that reduces incoming damage based on physical obstruction and angle. High AC does not remove or replace cover at the table.
What happens if my Dexterity drops to zero while wearing light armor?
Your AC becomes 10, because the formula for light armor is 10 + Dexterity modifier. A negative modifier lowers your AC, so you are more vulnerable until the effect ends or you change armor.