Rules Index | GM Screen | Player's Guide

Chapter 9: Playing the Game / General Rules / Damage

Step 4: If Damage Remains, Reduce the Target's Hit Points

Source Core Rulebook pg. 453 2.0
After applying the target’s immunities, resistances, and weaknesses to the damage, whatever damage is left reduces the target’s Hit Points on a 1-to-1 basis. More information about Hit Points can be found in the Hit Points, Healing, and Dying section.

Nonlethal Attacks

Source Core Rulebook pg. 453 2.0
You can make a nonlethal attack in an effort to knock someone out instead of killing them (see Knocked Out and Dying). Weapons with the nonlethal trait (including fists) do this automatically. You take a –2 circumstance penalty to the attack roll when you make a nonlethal attack using a weapon that doesn't have the nonlethal trait. You also take this penalty when making a lethal attack using a nonlethal weapon.

Spells and other effects with the nonlethal trait that reduce a creature to 0 Hit Points knock the creature out instead of killing them.