How Skills Work

Rules Index

Skills represent a character's learned capabilities outside of combat — knowledge, physical prowess, social interaction, and practical craft. Every skill is tied to one of the six ability scores, and most can be used untrained; a handful require at least one rank before they can be attempted at all. Understanding rank budgets, the class-skill bonus, and the Taking 10 / Taking 20 rules is essential for building a useful character at any level.

Skill Ranks

Each level you receive a budget of skill ranks equal to your class's base value plus your Intelligence modifier (minimum 1 rank per level, even with a negative INT score).

Skill ranks per level = class base + INT modifier (minimum 1). Ranks in any single skill cannot exceed your current character level. At 1st level you spend your full per-level budget — you do not receive extra ranks for "previous" levels.

Ranks stack directly: a character with 3 ranks in Perception adds +3 to every Perception check before ability modifiers or other bonuses. There is no diminishing return on ranks — every rank is worth exactly +1.

Class Skills and the +3 Bonus

Every class defines a list of class skills. Investing at least one rank in a class skill permanently unlocks a +3 competence bonus on that skill — the bonus applies for as long as you have at least one rank, regardless of how many ranks you add later.

Skill type	Bonus for 1+ ranks	Check total
Class skill	+3 competence bonus (permanent once unlocked)	Ranks + ability modifier + 3 + other bonuses
Cross-class skill	None	Ranks + ability modifier + other bonuses

A skill is a class skill if any of your classes lists it — multiclassing does not remove a class-skill bonus already earned. If you gain a level in a new class that lists a skill you already have ranks in as a cross-class skill, you do not retroactively gain the +3 bonus for those existing ranks; the bonus only applies to ranks invested after the new class is taken.

Trained-Only Skills

Skills marked Trained Only cannot be attempted at all without at least one rank — the character simply lacks the knowledge to try. These are not difficult checks; they are impossible checks. Common trained-only skills include:

Disable Device

Knowledge (any)

Linguistics

Profession (any)

Sleight of Hand

Spellcraft

Use Magic Device

The Knowledge skill family is a special case: each sub-skill (Arcana, History, Local, Nature, etc.) is a separate trained-only skill. A character with 1 rank in Knowledge (Arcana) cannot attempt Knowledge (Dungeoneering) untrained, even though both are "Knowledge" checks. Browse the full skill list to see which skills are trained-only.

Armor Check Penalty

Wearing armor or carrying a shield imposes an Armor Check Penalty (ACP) on all Strength- and Dexterity-based skill checks. The penalty applies to both class and cross-class skills. Characters proficient in the armor they are wearing reduce the ACP by their ranks in the relevant proficiency — except there is no "armor proficiency" skill; simply being proficient with a category of armor eliminates ACP for that category.

Affected skills include: Acrobatics, Climb, Escape Artist, Fly, Ride, Sleight of Hand, Stealth, Swim. The ACP appears in each armor's stat block. Heavy armor typically carries a –6 or higher penalty; light armor is –1 to –2 for most pieces.

Armor guide — ACP by armor type

Taking 10 and Taking 20

Take 10	When not in immediate danger or distracted, a character may choose to treat the d20 result as a 10. The check total is 10 + all modifiers. This is the default for routine tasks — crossing a rope bridge, picking a simple lock in a safe room, recalling basic knowledge. The GM decides when the situation prevents Taking 10.
Take 20	When there is no consequence for failure and unlimited time, a character may treat the d20 as a 20. This represents trying every possible approach until one works. Taking 20 takes 20× the normal check time and assumes the character fails many times in the process — it cannot be used on skills where failure carries a penalty (Disable Device on a trapped lock, for instance). The GM may rule that some tasks simply cannot be attempted 20 times in a row.

Take 10

When not in immediate danger or distracted, a character may choose to treat the d20 result as a 10. The check total is 10 + all modifiers. This is the default for routine tasks — crossing a rope bridge, picking a simple lock in a safe room, recalling basic knowledge. The GM decides when the situation prevents Taking 10.

Take 20

When there is no consequence for failure and unlimited time, a character may treat the d20 as a 20. This represents trying every possible approach until one works. Taking 20 takes 20× the normal check time and assumes the character fails many times in the process — it cannot be used on skills where failure carries a penalty (Disable Device on a trapped lock, for instance). The GM may rule that some tasks simply cannot be attempted 20 times in a row.

Aid Another

A character can attempt to help an ally with a skill check. The helper makes the same skill check against DC 10. Success grants the ally a +2 circumstance bonus on their check. Aid Another can be used on most skills, but the GM must rule that assistance is plausible — two people cannot both squeeze through a narrow gap at the same time, for example.

Some class features and feats (such as Cooperative Crafting) increase the Aid Another bonus beyond +2. Aid Another on an attack roll or AC also uses DC 10 and gives the same +2 bonus.

Browse all skills