Pathfinder Ability Score Modifier Calculator
Enter an ability score to calculate its modifier, used for attack rolls, saving throws, skill checks, and more in Pathfinder RPG.
Enter an ability score above and click Calculate.
Formula
Modifier = floor((Ability Score − 10) ÷ 2)
Examples:
- Score 10 → floor((10−10)/2) = +0
- Score 16 → floor((16−10)/2) = +3
- Score 8 → floor((8−10)/2) = floor(−1) = −1
- Score 1 → floor((1−10)/2) = floor(−4.5) = −5
Assumptions & References
- Formula is identical in Pathfinder 1st Edition and Pathfinder 2nd Edition core rules.
- The standard array of ability scores ranges from 3–18 at character creation (before racial bonuses).
- Scores below 10 produce negative modifiers; scores above 10 produce positive modifiers.
- A score of 10 or 11 both yield a modifier of +0 (floor of 0 and 0.5 respectively).
- Practical maximum score of 50 is used here; epic-level play or GM fiat may exceed this.
- A score of 0 is not entered here as it typically means the character is dead or incapacitated (treated as a special case in the rules, not a numeric modifier).
- Source: Pathfinder Core Rulebook, Paizo Publishing — Ability Scores chapter.