Player Core Chapter 8: Playing The Game Checks

Step 1: Roll D20

Start by rolling your d20. You'll then identify all the relevant modifiers, bonuses, and penalties that apply. 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.

Fortune and misfortune effects can alter how you roll your dice. These abilities might allow you to reroll a failed roll, force you to reroll a successful roll, allow you to roll twice and use the higher result, or force you to roll twice and use the lower result.
You can never have more than one fortune effect or misfortune effect come into play on a single roll. For instance, if an effect lets you roll twice and use the higher roll, you can't then use Meyel's Chosen (a fortune effect) to reroll if you fail. If multiple fortune effects would apply, you have to pick which to use. If two misfortune effects apply, the GM decides which is worse and applies it.
If both a fortune effect and a misfortune effect would apply to the same roll, the two cancel each other out, and you roll normally.

Attribute Modifier

Source Player Core pg. 392

Nearly all checks allow you to add an attribute modifier to the roll. Attribute modifiers represent your raw capability and are described in the sidebar here. Exactly which attribute modifier you use is determined by what you're trying to accomplish. Usually, firing a gun applies your Dexterity modifier, whereas remembering the name of the ambassador's pet uses your Intelligence modifier.

Bonuses

Source Player Core pg. 392

When attempting a check that involves something you have some training in, you 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 situational bonuses. 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.

There are three other types of bonus that frequently appear: circumstance bonuses, item bonuses, and status bonuses. If you have different types of bonuses 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—they aren't cumulative. 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, you add only the higher of the two.
Circumstance bonuses involve the situation you find yourself in when attempting a check. For instance, using Raise a Shield with a compact shield grants you a +1 circumstance bonus to AC. Being behind cover grants you a +2 circumstance bonus to AC.
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 a tactical holoskin grants you an item bonus to Impersonate someone using the Deception skill while wearing it.
Status bonuses typically come from spells, other magical effects, or something applying a helpful, often temporary, condition to you. For instance, the akashic download spell grants a +1 status bonus to a chosen Recall Knowledge check.

Proficiency Rank	Proficiency Bonus
Untrained	0
Trained	Your level + 2
Expert	Your level + 4
Master	Your level + 6
Legendary	Your level + 8

Penalties

Source Player Core pg. 392

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 an akashic download spell but a –2 status penalty from the sickened condition, you'd apply them both to your roll—so akashic download 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 of the turn, 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.

When creating your character and adventuring you'll record the total modifier for various important checks on your character sheet. Since many bonuses and penalties are due to the immediate circumstances, spells, and other temporary magical effects, you typically won't apply them to your notations.
For example, the number you write down for your attack modifier with your doshko would likely be your Strength modifier + your proficiency bonus with martial weapons. Your spell attack modifier is typically just your spellcasting attribute modifier + your proficiency bonus, and your spell DC is usually the same number + 10.
Item bonuses and penalties are often more persistent, so you'll often want to record them ahead of time. For instance, if you upgraded to a tactical doshko, you'll want to add the +1 item bonus into your attack modifier with the doshko since you'll include that bonus every time you attack with that weapon.