Ability score modifier

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

An Ability Score Modifier is a Die Roll modifier based on an Ability Score of a creature. It can affect every type of roll. Depending on the Ability Score in question, it can be shortened to Strength Modifier, Dexterity Modifier, Constitution Modifier, and so on.

When it's applied

Attack Roll

During Attack Rolls with Weapons, the attacking creature's Strength or Dexterity will be used to determine the Modifier. See the linked Attack Roll and Weapon pages for details.

For a spell that uses an Attack Roll, the Ability Score to be used depends on the Class of the creature casting the spell. For example, a Wizard uses Intelligence, a Cleric uses Wisdom, and a Sorcerer uses Charisma. See the Attack Roll page for details.

Damage Roll

For Damage Rolls made with Weapons, the exact same rules apply as for the Attack Roll.

For spells, the Ability Score Modifier is normally not used, though there are exceptions. For example, the class feature Agonising Blast allows a Warlock to add their Charisma Modifier to the damage of Eldritch Blast; and the spell Shillelagh imbues a weapon with magic, such that it benefits from the wielder's Wisdom Modifier.

Saving Throw

Each Saving Throw is tied to a certain Ability Score, which determines its type, such as Strength Saving Throw, Dexterity Saving Throw, and so on, which determines the Ability Score Modifier that will be used.

Ability Check

The Ability Check is similar to the Saving Throw in that it's categorized based on the Ability Score used. (The clue is in the name.)

A special type of Ability Check is the Skill Check, where a specific skill like Athletics, Perception, Sleight of Hand, etc. is used, but each Skill maps to a corresponding Ability Score, so the Ability Score Modifier still applies. For example, Athletics is based on Strength, whereas Sleight of Hand is based on Dexterity.

Value

Following is the table for the Ability Score Modifier value based on how high the corresponding Ability Score of a creature is:

Ability score modifier chart

Ability score	Modifier value		Ability score	Modifier value
1	-5		16-17	+3
2-3	-4		18-19	+4
4-5	-3		20-21	+5
6-7	-2		22-23	+6
8-9	-1		24-25	+7
10-11	+0		26-27	+8
12-13	+1		28-29	+9
14-15	+2		30	+10

Each ability score modifier is calculated according to the following formula Modifier = (Score − 10) ÷ 2 (round down) or more simply put, for every +1 increase to the modifier, the next highest score that is an even number must be reached. Odd-numbered scores provide no modifier increase beyond the even number below e.g. having a score of 13 in Intelligence provides no higher Intelligence modifier than having a score of 12. However, mechanics that are calculated directly based on an ability score (such as carrying capacity) do benefit by odd-numbered scores.