2.2.3 Armor Class

Your Armor Class (AC) represents how hard it is for opponents to land a solid damaging blow on you. Your Armor Class (AC) is the minimum attack roll result that an opponent needs to hit you and deal damage. Armor Class is divided into two categories: Energy Armor Class (EAC) and Kinetic Armor Class (KAC). Any reference to Armor Class, including bonuses and penalties, applies to both EAC and KAC unless otherwise specified.

Your EAC and KAC are primarily determined by your armor bonus (most often from a suit of armor you wear) plus your Dexterity modifier. Calculate your EAC and KAC using the following formula: 10 + your armor’s EAC or KAC armor bonus (whichever is appropriate) + your Dexterity modifier.

Most suits of armor provide separate armor bonuses to EAC and KAC. However, some suits of armor’s conditions prevent you from using your full Dexterity bonus. Various other bonuses can apply from class features, feats, special circumstances, and so on. For more information on bonuses, see 2.5 Bonuses and Penalties