how to determine ac in dnd 5e

3 min read 10-01-2025

Determining Armor Class (AC) in Dungeons & Dragons 5th Edition is crucial for your character's survival. A high AC means you're harder to hit, significantly impacting your chances of staying alive in combat. This guide will break down all the ways to calculate your AC, covering the basics and more advanced options.

Understanding Armor Class (AC)

Your Armor Class represents your character's overall defense against attacks. A higher AC means fewer successful hits. The lower your AC, the more likely you are to be hit. Let's dive into the various ways to determine your AC.

The Basic AC Calculation

The most common way to calculate your AC is using armor and a Dexterity modifier. The formula is generally:

AC = 10 + Dexterity Modifier + Armor Bonus

10: This is a base AC, representing unarmored defense.
Dexterity Modifier: This is determined by your character's Dexterity score. A higher Dexterity score grants a larger bonus.
Armor Bonus: This depends on the type of armor you're wearing. Different armors offer varying degrees of protection.

Different Armor Types and Their Bonuses

The armor bonus significantly impacts your AC. Here's a breakdown of common armor types and their bonuses:

Light Armor: (Leather, Studded Leather) Provides a +1 or +2 AC bonus.
Medium Armor: (Chain Mail, Scale Mail, Breastplate) Provides a +2 or +3 AC bonus.
Heavy Armor: (Plate Armor, Full Plate Armor) Provides a +2 to +5 AC bonus. Heavy armor often has a Strength requirement.

Shields: An Additional Layer of Defense

Shields add to your AC. A shield typically provides a +2 AC bonus. This bonus is added to your base AC calculation.

Unarmored Defense: For the Unprotected

Some classes and subclasses offer unarmored defense options. These typically involve using Dexterity and Constitution modifiers to calculate AC. Check your class features for specifics. Examples include:

Barbarians: Their rage feature enhances unarmored defense.
Monks: Their martial arts abilities grant increased unarmored defense.

Advanced AC Calculations: Beyond the Basics

Once you understand the foundation, let's explore situations that add complexity to AC determination:

Magical Armor and Items

Magical items can significantly boost your AC. Enchantments like +1, +2, or even +3 armor provide additional AC bonuses. These are added to your base AC.

Other Modifiers to AC

Certain spells, abilities, and conditions can alter your AC. These modifiers are added or subtracted from your total AC, based on the specific effect.

Calculating Your Effective AC

After considering all applicable bonuses and penalties, your effective AC is the final number used to determine whether an attack hits you.

Example AC Calculations

Let's look at a couple of examples to solidify your understanding:

Example 1: A Fighter in Plate Armor

Dexterity Modifier: +2
Plate Armor: +2 AC
Shield: +2 AC

AC = 10 + 2 + 2 + 2 = 16

Example 2: A Monk with Unarmored Defense

Dexterity Modifier: +3
Constitution Modifier: +1
Monk Unarmored Defense: 10 + Dex + Con

AC = 10 + 3 + 1 = 14

Frequently Asked Questions (FAQ)

Q: How does AC work against different attack types?

A: Your AC is used against all attacks, regardless of type (melee, ranged, etc.). However, some attacks might have special effects that bypass or ignore AC altogether.

Q: Can my AC ever go below 10?

A: Yes. Penalties to AC can reduce it below 10. However, it's extremely rare.

Q: What happens if my AC is higher than the attacker's attack roll?

A: If your AC is higher than the attacker's attack roll, the attack misses.

Conclusion

Mastering AC calculation is essential for success in D&D 5e. Understanding the different factors that contribute to your AC, from armor and shields to class features and magical enhancements, will significantly improve your character's survivability in combat. Remember to always double-check your AC before each encounter to ensure you're utilizing all available defensive options!