List of features and items that affect AC

Class features

Feature	Class	AC bonus	Notes
Defence (fighting style)	Fighter (1), Ranger (2), Paladin (2)	+1	Applies while wearing any armour
Unarmoured Defence (Barbarian)	Barbarian (1)	+CON modifier	Only applies while unarmoured. Affects base AC and does not stack with other effects that change base AC.
Unarmoured Defence (Monk)	Monk (1)	+WIS modifier	Only applies while unarmoured and not wearing a shield. Affects base AC and does not stack with other effects that change base AC.
Wild Shape	Druid (2)	Varies	While wild shaped, you take on the base AC of the form. This does not stack with other effects that change base AC. For a list of the base ACs of wild shape forms, see this list.
Draconic Resilience	Draconic Bloodline Sorcerer (3)	+3	Equivalent to  Mage Armour. Only applies while unarmoured. Affects base AC and does not stack with other effects that change base AC.

Spells

Spell	AC bonus	Duration	Concentration	Affects	Notes
Haste	+2	10 rounds	Yes	Self or allies
Shield	+5	Until the start of your next turn	No	Self	Cast as a reaction
Shield of Faith	+2	Until long rest	Yes	Self or allies
Warding Bond	+1	Until long rest	No	Allies
Mage Armour	+3	Until long rest	No	Self or allies	Only works while unarmoured. Affects base AC and does not stack with other effects that change base AC.
Mirror Image	+3 to +9	10 rounds (or until depleted)	No	Self	Starts at 3 mirror images for +9 AC. Each missed attack will remove one mirror image and reduce the AC bonus by 3.
Barkskin	Sets AC to 16	Until long rest	Yes	Self or allies	Has no effect if the target has an AC higher than 16.

Items

Item	AC bonus	Notes
Shields	+1 to +3	Most shields grant +2 AC. See Shields for a comprehensive list.
Light Armour	Varies	Light armours typically have AC values of 11 to 14. See Light Armour for a comprehensive list.
Medium Armour	Varies	Medium armours typically have AC values of 13 to 17, but cap the AC bonus from Dexterity to +2. This cap can be increased to +3 with  Medium Armour Master and armours with the Exotic Material property do not have this cap. See Medium Armour for a comprehensive list.
Heavy Armour	Varies	Heavy armours typically have AC values of 16 to 21, but do not get any AC bonus from Dexterity. A negative Dexterity modifier will still apply, however. See Heavy Armour for a comprehensive list.
Helm of Balduran	+1
Wondrous Gloves	+1
Bracers of Defence	+2	Only applies while unarmoured and not wielding a shield.
Ring of Protection	+1
Cloak of Protection	+1
Bonespike Boots	+1	Only applies while unarmoured and not wielding a shield.
Evasive Shoes	+1
Defender Flail	+1
Defender Greataxe	+1	When making an attack, can choose to reduce the weapon enchantment by 1 to gain +1 AC for 1 round.
Ring of Twilight	+1	AC bonus only applies while obscured.