Rules Index | GM Screen | Player's Guide

Chapter 9: Playing the Game / General Rules


Source Core Rulebook pg. 443 2.0
When success isn’t certain—whether you’re swinging a sword at a foul beast, attempting to leap across a chasm, or straining to remember the name of the earl’s second cousin at a soiree—you’ll attempt a check. Pathfinder has many types of checks, from skill checks to attack rolls to saving throws, but they all follow these basic steps.
  1. Roll a d20 and identify the modifiers, bonuses, and penalties that apply.
  2. Calculate the result.
  3. Compare the result to the difficulty class (DC).
  4. Determine the degree of success and the effect.
Checks and difficulty classes (DC) both come in many forms. When you swing your sword at that foul beast, you’ll make an attack roll against its Armor Class, which is the DC to hit another creature. If you are leaping across that chasm, you’ll attempt an Athletics skill check with a DC based on the distance you are trying to jump. When calling to mind the name of the earl’s second cousin, you attempt a check to Recall Knowledge. You might use either the Society skill or a Lore skill you have that’s relevant to the task, and the DC depends on how common the knowledge of the cousin’s name might be, or how many drinks your character had when they were introduced to the cousin the night before.

No matter the details, for any check you must roll the d20 and achieve a result equal to or greater than the DC to succeed. Each of these steps is explained below.

Step 1: Roll d20 and Identify the Modifiers, Bonuses, and Penalties that Apply

Source Core Rulebook pg. 444 2.0
Start by rolling your d20. You’ll then identify all the relevant modifiers, bonuses, and penalties that apply to the roll. A modifier can be either positive or negative, but a bonus is always positive, and a penalty is always negative. The sum of all the modifiers, bonuses, and penalties you apply to the d20 roll is called your total modifier for that statistic.

Nearly all checks allow you to add an ability modifier to the roll. An ability modifier represents your raw capabilities and is derived from an ability score, as described on page 20. Exactly which ability modifier you use is determined by what you’re trying to accomplish. Usually a sword swing applies your Strength modifier, whereas remembering the name of the earl’s cousin uses your Intelligence modifier.

When attempting a check that involves something you have some training in, you will also add your proficiency bonus. This bonus depends on your proficiency rank: untrained, trained, expert, master, or legendary. If you’re untrained, your bonus is +0—you must rely on raw talent and any bonuses from the situation. Otherwise, the bonus equals your character’s level plus a certain amount depending on your rank. If your proficiency rank is trained, this bonus is equal to your level + 2, and higher proficiency ranks further increase the amount you add to your level.

Proficiency Bonus

Proficiency RankProficiency Bonus
TrainedYour level + 2
ExpertYour level + 4
MasterYour level + 6
LegendaryYour level + 8

There are three other types of bonus that frequently appear: circumstance bonuses, item bonuses, and status bonuses. If you have different types of bonus that would apply to the same roll, you’ll add them all. But if you have multiple bonuses of the same type, you can use only the highest bonus on a given roll—in other words, they don’t “stack.” For instance, if you have both a proficiency bonus and an item bonus, you add both to your d20 result, but if you have two item bonuses that could apply to the same check, you add only the higher of the two.

Circumstance bonuses typically involve the situation you find yourself in when attempting a check. For instance, using Raise a Shield with a buckler grants you a +1 circumstance bonus to AC. Being behind cover grants you a +2 circumstance bonus to AC. If you are both behind cover and Raising a Shield, you gain only the +2 circumstance bonus for cover, since they’re the same type and the bonus from cover is higher.

Item bonuses are granted by some item that you are wearing or using, either mundane or magical. For example, armor gives you an item bonus to AC, while expanded alchemist’s tools grant you an item bonus to Crafting checks when making alchemical items.

Status bonuses typically come from spells, other magical effects, or something applying a helpful, often temporary, condition to you. For instance, the 3rd-level heroism spell grants a +1 status bonus to attack rolls, Perception checks, saving throws, and skill checks. If you were under the effect of heroism and someone cast the bless spell, which also grants a +1 status bonus on attacks, your attack rolls would gain only a +1 status bonus, since both spells grant a +1 status bonus to those rolls, and you only take the highest status bonus.

Penalties work very much like bonuses. You can have circumstance penalties, status penalties, and sometimes even item penalties. Like bonuses of the same type, you take only the worst all of various penalties of a given type. However, you can apply both a bonus and a penalty of the same type on a single roll. For example, if you had a +1 status bonus from a heroism spell but a –2 status penalty from the sickened condition, you’d apply them both to your roll—so heroism still helps even though you’re feeling unwell.

Unlike bonuses, penalties can also be untyped, in which case they won’t be classified as “circumstance,” “item,” or “status.” Unlike other penalties, you always add all your untyped penalties together rather than simply taking the worst one. For instance, when you use attack actions, you incur a multiple attack penalty on each attack you make on your turn after the first attack, and when you attack a target that’s beyond your weapon’s normal range increment, you incur a range penalty on the attack. Because these are both untyped penalties, if you make multiple attacks at a faraway target, you’d apply both the multiple attack penalty and the range penalty to your roll.

Once you’ve identified all your various modifiers, bonuses, and penalties, you move on to the next step.

Step 2: Calculate the Result

Source Core Rulebook pg. 445 2.0
This step is simple. Add up all the various modifiers, bonuses, and penalties you identified in Step 1—this is your total modifier. Next add that to the number that came up on your d20 roll. This total is your check result.

Step 3: Compare the Result to the DC

Source Core Rulebook pg. 445 2.0
This step can be simple, or it can create suspense. Sometimes you’ll know the Difficulty Class (DC) of your check. In these cases, if your result is equal to or greater than the DC, you succeed! If your roll anything less than the DC, you fail.

Other times, you might not know the DC right away. Swimming across a river would require an Athletics check, but it doesn’t have a specified DC—so how will you know if you succeed or fail? You call out your result to the GM and they will let you know if it is a success, failure, or otherwise. While you might learn the exact DC through trial and error, DCs sometimes change, so asking the GM whether a check is successful is the best way to determine whether or not you have met or exceeded the DC.

Calculating DCs

Source Core Rulebook pg. 445 2.0
Whenever you attempt a check, you compare your result against a DC. When someone or something else attempts a check against you, rather than both forces rolling against one another, the GM (or player, if the opponent is another PC) compares their result to a fixed DC based on your relevant statistic. Your DC for a given statistic is 10 + the total modifier for that statistic.

Step 4: Determine the Degree of Success

Source Core Rulebook pg. 445 2.0
Many times, it's important to determine not only if you succeed or fail, but also how spectacularly you succeed or fail. Exceptional results—either good or bad—can cause you to critically succeed at or critically fail a check.

You critically succeed at a check when the check's result meets or exceeds the DC by 10 or more. If the check is an attack roll, this is sometimes called a critical hit. You can also critically fail a check. The rules for critical failure—sometimes called a fumble—are the same as those for a critical success, but in the other direction: if you fail a check by 10 or more, that's a critical failure.

If you rolled a 20 on the die (a “natural 20”), your result is one degree of success better than it would be by numbers alone. If you roll a 1 on the d20 (a “natural 1”), your result is one degree worse. This means that a natural 20 usually results in a critical success and natural 1 usually results in a critical failure. However, if you were going up against a very high DC, you might get only a success with a natural 20, or even a failure if 20 plus your total modifier is 10 or more below the DC. Likewise, if your modifier for a statistic is so high that adding it to a 1 from your d20 roll exceeds the DC by 10 or more, you can succeed even if you roll a natural 1! If a feat, magic item, spell, or other effect does not list a critical success or critical failure, treat is as an ordinary success or failure instead.

Some other abilities can change the degree of success for rolls you get. When resolving the effect of an ability that changes your degree of success, always apply the adjustment from a natural 20 or natural 1 before anything else.