How armor class works in DnD 5e

Learn how armor class works and how to improve your AC

How to calculate armor class

At its most basic level, armor class is calculated as:

10 + dexterity modifier

So if your character has a dexterity of 16 (+3), then their armor class will be 10 + 3 or 13.

You can increase your armor class through other ways than just having a high dexterity though. Wearing armor is the most common way to improve your armor class further. In addition, racial traits, magic items and spells can all be employed to improve your armor class. Below we’ve detailed how some of these additional methods work to boost your AC.

How to improve your armor class

Armor

Armour improves your AC by improving your base AC at which armour class is calculated. For instance, if your character is wearing studded leather armour, they calculate their AC based on 12 + their dexterity modifier rather than the usual 10 when unarmored.

Light armor like studded leather works really well for characters with a lot of dexterity as it enhances your natural, agile defences without limiting your bonus from having a high dexterity.

Some characters may be less agile, in which case, they may choose to wear medum or heavy armour. This usually increases your base AC by more than light armor, but often means you can only benefit from your dexterity modifier in a limited way (or not at all) due to the restricted movement. For example, a character wearing half plate will have an AC of 15 + their dexterity modifier but with a maximum of +2 to that value from their dexterity modifier.

Heavy armor will negate the impact of dexterity entirely from your armor class, but with the benefit of a higher base AC. For example, plate armor provides a flat AC of 18.

Just remember that you’ll need to be proficient in an armor type to gain the benefits of wearing it. Some armor types will also make it harder to perform stealth actions or might be so heavy, they require a certain strength to wear effectively.

Below I’ve added information on all the standard forms of armor to help you choose the right armor for your character:

Armor	Type	Cost	Armor Class	Strength Modifier	Stealth	Weight
Padded	Light Armor	5gp	11 + Dex Modifier	N/A	Disadvantage	8 lb
Leather	Light Armor	10gp	11 + Dex Modifier	N/A	N/A	10 lb
Studded Leather	Light Armor	45gp	12 + Dex Modifier	N/A	N/A	13 lb
Hide	Medium Armor	10gp	12 + Dex Modifier (Max +2)	N/A	N/A	12 lb
Chain Shirt	Medium Armor	50gp	13 + Dex Modifier (Max +2)	N/A	N/A	20 lb
Scale mail	Medium Armor	50gp	14 + Dex Modifier (Max +2)	N/A	Disadvantage	45 lb
Breast Plate	Medium Armor	400gp	14 + Dex Modifier (Max +2)	N/A	N/A	20 lb
Half Plate	Medium Armor	750gp	15 + Dex Modifier (Max +2)	N/A	Disadvantage	40 lb
Ring Mail	Heavy Armor	30gp	14	N/A	Disadvantage	40 lb
Chain Mail	Heavy Armor	75gp	16	Str 13	Disadvantage	55 lb
Splint	Heavy Armor	200gp	17	Str 15	Disadvantage	60 lb
Plate	Heavy Armor	1500gp	18	Str 15	Disadvantage	65 lb

Shields

Shields operate a little differently from armor. A character can wield a single shield (so no double shields like Captain America I’m afraid… Well, you could but you’d only gain the benefit of the one shield and could only use the second shield as an improvised weapon so not the most effective approach). A standard shield will give you +2 to whatever your armor class is, so a great way to boost your AC. The only drawback is that your hand can’t now be used for something else like wielding a two-handed weapon, dual wielding weapons or for spellcasting.

Racial Traits

A handful of races have a natural hardiness that increases their AC naturally. Such features are rare for races as an AC bonus at level 1 can be a powerful bonus and make you extremely difficult to hit if optimised right. Those races are:

Autognome – Base AC of 13 when not wearing armor (better than any standard light armor).

Lizardfolk – Base AC of 13 when not wearing armor (again, better than any standard light armor).

Locathah – Base AC of 12 when not wearing armor.

Loxodon – Base AC of 12 when not wearing armor.

Shifter – Can shift to increase AC by +1

Simic Hybrid – Can take an option at level 5 to increase AC by +1 when not wearing heavy armor.

Thri-Kreen – Base AC of 13 when not wearing armor (also, better than any standard light armor).

Tortles – Tortles have a naturally tough shell that also makes wearing armor extremely difficult. Tortles have a base AC of 17 that is unaffected by dexterity modifiers. They also can’t gain the benefits of wearing armor (though can benefit from using a shield).

In addition, they can retreat into their shell for an extra +4 AC but are very limited in what they can do in this position.

Warforged – Warforged have a +1 to their AC.

Class Features

Some classes have traits that allow them to increase their armor class. Often due to being extremely hardy or highly trained in certain techniques. These classes are:

Artificer – Artificers love to tinker with things to improve their functionality, this includes enhancing armor with infusions. Their infusions allow them to grant a +1 bonus to the AC granted by armor or a shield which increases to +2 when they reach level 10.

Barbarian – Barbarians are warriors specialised in being very tanky and can both deal and take a lot of damage. Their unarmored defence trait means they can also add their constitution modifier to their AC meaning their AC is calculated as:

10 + dexterity modifier + constitution modifier

Fighter – Fighters are highly trained warriors that can train in certain fighting styles. One of these styles is the defence fighting style which adds +1 to a fighter’s AC while they’re wearing armor.

Monk – Monks are highly trained warriors that can weave in and out of opponents relying more on skill than armor to protect them. Their unarmored defence allows them to add their wisdom modifier to their armor class meaning their AC is calculated as:

10 + dexterity modifier + wisdom modifier

A couple of subclasses also add bonuses to AC. These are:

Forge Domain Cleric – Their Soul of the Forge ability adds +1 to their AC when wearing heavy armour.

Bladesinging Wizard – Bladesingers use their bladesong ability to help them operate on the front lines of combat allowing them to add their intelligence modifier to their AC meaning their armour class is worked out as:

10 + dexterity modifier + intelligence modifier

Feats

Feats can be taken (if your DM allows them) in place of ability score improvements when levelling up. They represent unique traits that can provide skills not generally available to a particular class. Some of these feats can be used to improve your AC, these include:

• Defensive duelist – You can use your reaction to add your proficiency bonus to your AC
• Dragon Hide – Your base AC is 13 + your dexterity modifier
• Duel Wielder – Gain +1 to AC when duel wielding
• Heavily Armored – Gain proficiency with heavy armor
• Lightly Armored – Gain proficiency with light armor
• Medium Armor Master – Your dexterity modifier when wearing medium armor can be a maximum of +3 instead of +2
• Moderately Armored – Gain proficiency with medium armor and shields

Spells

A lot of spells can be used to provide various buffs to a character and a few of these can be used to increase a character’s armor class. This can be particularly useful if you’re a spellcaster like a wizard with few other defences. It’s also great if you’re well-armored, but thrown so much into the thick of combat that you may need some extra protection as can be the case with a paladin. It should be noted though, that these spells only provide temporary enhancements to AC that can last as little as a turn.

These AC enhancing spells include:

• Barkskin – AC is at least 16
• Ceremony (Wedding) – +2 AC while both creatures are within 30ft of each other
• Haste – +2 AC along with other bonuses
• Mage Armor – Base AC becomes 13 + Dexterity Modifier
• Polymorph/True Polymorph – Creature gains the AC of the creature it was turned into 
• Shield – Reaction that increases AC by 5 for a round
• Shield of Faith – +2 AC
• Tasha’s Otherworldly Guise – +2 AC along with other benefits
• Warding Bond – +1 AC along with other benefits

Magic Items

Magic items are powerful and more rare than other standard items you might acquire. There’s no guarantee that your DM will bestow an AC increasing item upon your party but they are there and available in the game if included by your DM. Often, these magic items might include enhanced sets of armor that provide additional bonuses to AC or robes, rings and amulets imbued with powerful magic to protect its wearer.

You can find details of armor class enhancing magic items in the Dungeon Master’s Guide.

Cover

Cover is easily forgotten about as a way to enhance AC, particularly because it’s highly situational and can’t be relied on, but different types of cover provide varying levels of AC bonus. It might be a low wall, some battlements, a tree or even the dead husk of some huge creature. Below, we’ve detailed the types of cover and the AC bonus provided by it:

Half Cover (+2 AC) – Half cover involves anything that covers about half your body and might include furniture, low walls, battlements and even another creature.

Three-Quarters Cover (+5 AC) – This involves anything that covers about three quarters of your body which might include arrow slits in a keep, a large tree trunk or a wagon.

Total Cover – If you’re in total cover and are entirely obscured from view, you can’t be targeted in the conventional sense. It is possible though that an area of effect spell might still hit you under these circumstances and if cast in the right place.

In the case of cover, it is for your DM to determine how well a piece of cover protects your character.

Best character builds for high armor class

This is a tricky question and depends on what your DM is willing to allow. Some of the craziest high armor class builds rely on magic items, spells and some very hefty multiclassing to stack benefits that I imagine most DMs wouldn’t allow at their table.

For the purposes of this question, we’ll work with a few assumptions. First, we will assume that you have no magic items to benefit from as there’s no guarantee you will have a DM generous enough to bestow a multitude of armor class enhancing gear on you (or a party willing to let you take all the loot to make you near indestructible). Also, note that spells are temporary so we’ve highlighted AC with and without spells.

With those ground rules out of the way, here’s some of the highest AC builds available in D&D 5e:

Paladin or fighter – Paladins and fighters can both use heavy armor so you’ll want to equip plate mail and a shield for an AC of 20. You’ll then need to take the defence fighting style which will bring your AC up to 21. If you choose to play as a warforged, this will increase your AC a little more up to 22. We won’t include it in this calculation, but paladins can have access to the shield spell which it’s worth bearing in mind will increase your AC by +5 for a turn as a reaction.

Barbarians and Monks – Barbarians and Monks have a feature called unarmored defence which allows them to add their dexterity modifier and either their constitution or wisdom modifier to their AC. If you can achieve +5 to both these modifiers, this gets you to an AC of 20 without armor. A warforged will give you +1 bringing you up to 21.

You could also take a shield if you’re a barbarian for an AC of 23. While the monk can’t take a shield, they can take the dual wielder feat, have 2 weapons and get a +1 to their AC taking you up to 22. For an even bigger bonus, you can even take the defensive duelist feat which will allow you to add your proficiency bonus to your AC as a reaction. This means a potential for +6 to your AC but can only be taken against one attack per turn but does mean a potential AC of 28 on a reasonably regular basis!