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.

Ability Scores and Modifiers

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

To determine an ability modifier without consulting the table, subtract 10 from the ability score and then divide the total by 2 (round down).

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.