Difficulty Class

For a comprehensive summary of the mechanics behind all rolls and modifiers, see Die Rolls.

Difficulty Class (or DC) is a number that must be matched or exceeded to achieve success when rolling for Ability Checks or Saving Throws.

When attempting to beat - called a Saving Throw - a Difficulty Class, the die rolled is a  d20. The modifiers applied to this roll vary, depending on the circumstances and the type of check.

The Difficulty Class (DC) is determined by the source of danger.

Danger DC

In scenarios such as traps, the game chooses an appropriate Difficulty Class, depending on how serious the danger is. This includes single-use items such as elemental arrows or throwables.

Spellcasting DC

For the Difficulty Class of a Spell that imposes a Saving Throw, the DC is determined by the creature's Spellcasting Ability Modifier, using the following formula:

Difficulty Class = 8 + Proficiency Bonus + Spellcasting Ability Modifier

Weapon Action DC

The Difficulty Class for Saving Throws against Weapon Actions is calculated similarly to Spellcasting DC - except for four differences: firstly, the Spellcasting Ability Modifier is replaced with the Ability Modifier of either Strength or Dexterity, whichever is higher; secondly, proficiency bonus isn't added; thirdly, the base DC is 10 instead of 8; and finally, each Weapon Action can grant its own inherent bonus DC that isn't listed anywhere, but most frequently it's +2. To express all this mathematically:

Weapon Action DC = 10 + Strength or Dexterity + Inherent Weapon Action Bonus DC

Certain Weapon Actions, notably Concussive Smash, instead use Hybrid DC, which allows a user to either use their Spellcasting DC, or Weapon Action DC with a +2 bonus, whichever is higher.