DnD 5e AC Calculator
Enter armor, abilities, gear, spells, cover, and attack details. The result appears above this form after calculation.
Example Data Table
| Build |
Method |
Main Inputs |
Common AC |
Notes |
| Rogue |
Standard Armor |
Studded leather, Dex 18 |
16 |
No shield. Good stealth. |
| Fighter |
Heavy Armor |
Plate, shield |
20 |
Strength need applies. |
| Wizard |
Mage Armor |
Mage armor, Dex 14 |
15 |
Shield spell can raise it to 20. |
| Barbarian |
Unarmored Defense |
Dex 14, Con 16, shield |
17 |
Shield can apply. |
| Monk |
Unarmored Defense |
Dex 16, Wis 16 |
16 |
Shield is normally not allowed. |
Formula Used
The calculator starts with the selected base AC rule. It then adds the allowed ability modifier. After that, it adds valid shields, items, spells, cover, traits, feats, and manual adjustments.
| Rule Type |
Formula |
| No Armor |
AC = 10 + Dexterity modifier |
| Light Armor |
AC = Armor base + full Dexterity modifier |
| Medium Armor |
AC = Armor base + Dexterity modifier, capped at +2 |
| Heavy Armor |
AC = Armor base. Dexterity is not added. |
| Mage Armor |
AC = 13 + Dexterity modifier |
| Barbarian |
AC = 10 + Dexterity modifier + Constitution modifier |
| Monk |
AC = 10 + Dexterity modifier + Wisdom modifier |
| Hit Chance |
Roll d20 + attack bonus against AC. Natural 1 misses. Natural 20 hits. |
How To Use This Calculator
- Enter your character name and level.
- Choose the AC method that matches your character sheet.
- Select armor, Dexterity, and any class ability scores.
- Add shield, magic items, spells, cover, and extra bonuses.
- Enter an enemy attack bonus to estimate hit chance.
- Press Calculate AC and review the breakdown above the form.
- Use CSV or PDF export to save the result.
Armor Class In Play
Armor Class decides how hard a character is to hit. It is not only metal armor. It also reflects reflexes, shields, magic, cover, and class features. A good AC estimate helps players compare builds before the session starts.
Why AC Changes
Your base value comes from an armor rule or a special feature. Light armor uses the full Dexterity modifier. Medium armor limits Dexterity to two unless a table option changes it. Heavy armor ignores Dexterity. Some characters use Unarmored Defense instead. A barbarian adds Dexterity and Constitution. A monk adds Dexterity and Wisdom. Mage armor gives a magical base of thirteen plus Dexterity.
Advanced Bonuses
Many bonuses stack because they come from different sources. A shield usually adds two. Magic armor and magic shields add their item values. Defensive fighting, haste, shield of faith, cover, rings, cloaks, and temporary spell effects may also apply. The calculator separates these parts so the final number stays clear.
Hit Chance Context
A high AC feels stronger when enemies have modest attack bonuses. An enemy with a low attack bonus may need a very high roll. A powerful foe can still hit often. The hit chance estimate uses the natural one and natural twenty rule. That means a one fails and a twenty hits, even when the total looks extreme.
Build Planning Tips
Use the tool before choosing armor. Compare stealth penalties, strength needs, and spell options. A rogue may prefer studded leather for stealth. A fighter may choose plate and a shield. A caster may test mage armor with the shield spell active. Always check your table rules, because feats, race traits, magic items, and homebrew can change the final answer.
Using Results
Treat the result as a combat planning aid. It is not a replacement for your character sheet. Record normal AC and temporary AC separately. During play, tell your Dungeon Master which active effects are included. Clear tracking reduces disputes and keeps combat fast.
Keep one saved result for travel, one for dungeon fights, and one for emergencies. This makes quick choices easier when a spell, shield, or cover bonus suddenly matters most at the table.
FAQs
What does AC mean in DnD 5e?
AC means Armor Class. It is the target number an attack roll must meet or beat to hit your character, after normal roll rules apply.
Does Dexterity always add to AC?
No. Light armor uses full Dexterity. Medium armor usually caps Dexterity at +2. Heavy armor ignores Dexterity. Special features can use different rules.
Can a shield stack with armor?
Yes. A normal shield usually adds +2 AC. Magic shield bonuses can add more. Some features, like Monk Unarmored Defense, may restrict shields.
Why was my bonus ignored?
The calculator ignores bonuses that conflict with common rules. For example, Bracers of Defense do not work while armor or a shield is active.
Does cover increase AC?
Yes. Half cover usually adds +2 AC. Three-quarters cover usually adds +5 AC. Total cover normally prevents direct targeting.
How is enemy hit chance estimated?
The calculator checks d20 rolls against your AC. It also respects natural 1 misses and natural 20 hits, then adjusts for advantage or disadvantage.
Can I use this for homebrew armor?
Yes. Choose Custom Base AC. Then select whether Dexterity applies fully, is capped at +2, or does not apply.
Should temporary effects be saved separately?
Yes. Keep normal AC and temporary AC apart. This helps during combat when spells, reactions, cover, and magic effects change quickly.