Pathfinder Skill Check Probability Calculator
Calculate the probability of succeeding on a Pathfinder skill check (1d20 + modifier vs. DC). Includes critical success and critical failure chances per Pathfinder 2e rules.
Sum of ability modifier + proficiency bonus + item bonus + status bonus + circumstance bonus, etc.
The target number set by the GM or ability description.
Results will appear here.
Formulas
Core roll: d20 + Total Modifier ≥ DC → Success
Pathfinder 1e / D&D 3.5 (simple pass/fail):
- Natural 1 always fails on skill checks; Natural 20 does not auto-succeed on skill checks in PF1e.
Pathfinder 2e (four degrees of success):
Assumptions & References
- PF2e degrees of success follow the Pathfinder 2e Core Rulebook, p. 445–446 (natural 1/20 degree shift rules).
- PF1e skill checks do not have automatic success on a natural 20 (unlike attack rolls); a natural 1 always fails.
- DC values: Common DCs in PF2e range from 14 (level 1) to 50 (level 25+); see the PF2e GM Core DC-by-level table.