Formula used
Armor Class starts with one valid base formula. Shields and permitted bonuses are added afterward. Incompatible base formulas never stack within this calculator.
Normal AC = Valid base AC + shield + permanent modifiers Temporary AC = Normal AC + active temporary modifiers One-attack AC = Temporary AC + situational modifiers + reactions
How to use this calculator
Select one base method matching your character. Add equipment, features, spells, items, and situational effects. Review every warning before using the result during play.
- Choose the ruleset and enter ability scores.
- Select exactly one base Armor Class formula.
- Add shields, features, spells, feats, and items.
- Enter cover and enemy attack information.
- Calculate, compare, export, or save the configuration.
Example data
| Example | Base | Shield | Other bonuses | Normal AC |
|---|---|---|---|---|
| Plate defender | Plate 18 | +2 | Defense Style +1 | 21 |
| Studded leather scout | 12 + Dexterity +4 | None | Cloak +1 | 17 |
| Barbarian guardian | 10 + Dexterity + Constitution | +2 | Ring +1 | Varies |
Armor reference table
| Armor | Category | Base | Dexterity | Strength | Stealth disadvantage | Weight | Don | Doff |
|---|---|---|---|---|---|---|---|---|
| Padded | Light | 11 | Full modifier | — | Yes | 8 lb | 1 minute | 1 minute |
| Leather | Light | 11 | Full modifier | — | No | 10 lb | 1 minute | 1 minute |
| Studded leather | Light | 12 | Full modifier | — | No | 13 lb | 1 minute | 1 minute |
| Hide | Medium | 12 | Maximum +2 | — | No | 12 lb | 5 minutes | 1 minute |
| Chain shirt | Medium | 13 | Maximum +2 | — | No | 20 lb | 5 minutes | 1 minute |
| Scale mail | Medium | 14 | Maximum +2 | — | Yes | 45 lb | 5 minutes | 1 minute |
| Breastplate | Medium | 14 | Maximum +2 | — | No | 20 lb | 5 minutes | 1 minute |
| Half plate | Medium | 15 | Maximum +2 | — | Yes | 40 lb | 5 minutes | 1 minute |
| Ring mail | Heavy | 14 | None | — | Yes | 40 lb | 10 minutes | 5 minutes |
| Chain mail | Heavy | 16 | None | 13 | Yes | 55 lb | 10 minutes | 5 minutes |
| Splint | Heavy | 17 | None | 15 | Yes | 60 lb | 10 minutes | 5 minutes |
| Plate | Heavy | 18 | None | 15 | Yes | 65 lb | 10 minutes | 5 minutes |
Frequently asked questions
Can two base AC formulas stack?
No, one valid base formula applies at once. Compare alternatives and use the formula allowed by rules. Your Dungeon Master resolves unusual interactions at the table.
Does heavy armor add Dexterity?
Heavy armor normally uses its listed fixed value. Positive and negative Dexterity modifiers are usually ignored. Check special features before finalizing your character’s Armor Class.
How does medium armor limit Dexterity?
Medium armor normally adds up to two Dexterity points. Medium Armor Master can raise that limit when applicable. Confirm feat wording within your selected ruleset before play.
Does a magical shield replace its normal bonus?
A magical shield usually includes the standard shield value. Its enhancement is added to that normal contribution. Enter both through the shield controls for accurate totals.
Are reactions included in normal AC?
No, reactions appear in the one-attack scenario. They may consume resources or require specific triggering attacks. Apply them only when every listed condition is satisfied.
How is advantage hit chance calculated?
Advantage rolls two d20s and keeps the higher. The calculator converts normal probability using standard independent rolls. Critical rules may change through specific features or effects.
What does total cover do?
Total cover is not represented as another AC bonus. It normally prevents direct targeting by covered attacks. Determine line of effect using the current battlefield layout.
Why does the calculator show warnings?
Warnings identify common conflicts and missing requirements. They do not replace complete rules text or rulings. Review every warning before applying the calculated Armor Class.
Can custom bonuses represent homebrew content?
Yes, custom fields support homebrew and unusual effects. Enter bonuses only after confirming their stacking behavior. Record the source so other players can verify everything.
Rules disclaimer
This tool estimates Armor Class from entered selections. Published wording, errata, and table rulings may differ. The Dungeon Master always has final authority during play.