Ability Score Modifier

The number you add to your rolls based on your ability scores.

Ability Scores and Modifiers

Each of a creature's abilities has a score, a number that defines the magnitude of that ability. An ability score is not just a measure of innate capabilities, but also encompasses a creature's training and competence in activities related to that ability.

A score of 10 or 11 is the normal human average, but adventurers and many monsters are a cut above average in most abilities.

A score of 18 is the highest that a person usually reaches. Adventurers can have scores as high as 20, and monsters and divine beings can have scores as high as 30.

Each ability also has a modifier, derived from the score and ranging from -5 (for an ability score of 1) to +10 (for a score of 30).

The Ability Scores and Modifiers table notes the ability modifiers for the range of possible ability scores, from 1 to 30.

Table - Ability Scores and Modifiers

Determining an ability score modifier without consulting the table: (Ability Score - 10) / 2, rounded down.

For example, your Fighter has a Strength of 17.
Subtract 10: 17 - 10 = 7
Divide by 2: 7 / 2 = 3.5
Round Down: 3.5 becomes 3.
Result: Your modifier is +3.

Because ability modifiers affect almost every attack roll, ability check, and saving throw, ability modifiers come up in play more often than their associated scores.