Secret Lesson 5

Ability Checks, Skills, and Difficulty Classes

You already know that there are three types of D20 Test:

Ability Checks

Saving Throws

Attack Rolls

Now we are going to examine the first of these in detail:

THE ABILITY CHECK

Ability Checks are one of the game's main tools for resolving uncertain actions outside the normal process of making an attack.

They appear constantly during:

Exploration

Social Interaction

and many other situations in which a character tries to accomplish something and failure could meaningfully change what happens next.

The SRD describes an Ability Check as a creature using its talent and training to overcome a challenge. It gives examples such as forcing open a stuck door, picking a lock, entertaining a crowd, or deciphering a cipher.

WHEN DO YOU MAKE AN ABILITY CHECK?

A character does not make an Ability Check simply because they perform an action.

The important questions are:

Is the outcome uncertain?

and

Would failure actually matter?

The SRD explains that Ability Checks are commonly called for when a creature attempts something other than an attack that has a chance of meaningful failure, particularly when the result is uncertain and narratively interesting.

This is an extremely important principle.

NO MEANINGFUL UNCERTAINTY, NO CHECK

Imagine a character says:

“I pick up the book from the table.”

If nothing unusual prevents that action, there is probably no reason to roll.

The GM can simply say:

“You pick up the book.”

Now imagine:

“I try to pull the ancient book from the stone pedestal while a magical force holds it in place.”

That situation may have meaningful uncertainty.

An Ability Check might now be appropriate.

FAILURE SHOULD MATTER

Suppose a character wants to climb a small ladder under normal conditions.

There may be little reason for an Ability Check.

Now suppose the character is climbing a dangerous cliff during a violent storm.

Failure could have consequences.

The check now becomes much more meaningful.

The dice are not there to make ordinary actions unnecessarily random.

They are used when uncertainty has an important role in the scene.

THE ABILITY CHECK FORMULA

An Ability Check follows the D20 Test structure you learned in Lesson 4.

The basic form is:

d20 + Relevant Ability Modifier

Then, if an appropriate skill or tool proficiency applies:

+ Proficiency Bonus

Other rules can also provide bonuses or penalties.

Finally, compare the total with the:

DIFFICULTY CLASS — DC

If the total equals or exceeds the DC:

the check succeeds.

If the total is below the DC:

the check fails.

The SRD establishes that the relevant Ability Modifier is determined by what the character is trying to accomplish, and that Proficiency Bonus is added when an applicable skill or tool proficiency is relevant and the creature has that proficiency.

THE SIX TYPES OF ABILITY CHECK

Ability Checks are named after the Ability Modifier being used.

For example:

Strength Check

Dexterity Check

Constitution Check

Intelligence Check

Wisdom Check

Charisma Check

 

Let's look at the broad role of each one.

STRENGTH CHECKS

A Strength Check is appropriate when physical power is the main challenge.

The SRD gives examples such as:

  • lifting

  • pushing

  • pulling

  • breaking something

 

For example:

“I try to force the heavy gate open.”

The GM might call for a:

Strength Check

DEXTERITY CHECKS

A Dexterity Check is appropriate when the challenge depends mainly on agility, precision, speed, or quiet movement.

The SRD summarizes this as moving:

  • nimbly

  • quickly

  • quietly

 

For example:

“I try to move silently past the guard.”

That can involve Dexterity.

CONSTITUTION CHECKS

A Constitution Check represents pushing your body beyond its normal limits.

This is different from using Strength.

Strength concerns physical force.

Constitution concerns endurance.

For example, a challenge might involve continuing through extreme physical strain rather than lifting or breaking something.

INTELLIGENCE CHECKS

An Intelligence Check involves:

  • reasoning

  • remembering information

 

For example:

“Do I remember anything about this ancient civilization?”

or:

“Can I work out how this mechanism functions?”

Intelligence can be the relevant ability.

WISDOM CHECKS

A Wisdom Check is commonly used to:

  • notice things in the environment

  • notice meaningful details in a creature's behavior

 

For example:

“Do I notice the creature hiding among the rocks?”

or:

“Does this person seem sincere?”

Wisdom can be relevant.

CHARISMA CHECKS

A Charisma Check is associated with:

  • influencing

  • entertaining

  • deceiving

 

For example:

“I try to convince the guard to let us pass.”

or:

“I tell the merchant a convincing lie.”

Charisma can be the appropriate ability.

ABILITY CHECKS AND SKILLS

Most Ability Checks involve a skill.

A skill represents a category of activities that a creature might attempt using an Ability Check.

The rules for actions and other game effects often specify which skill is relevant, but the GM has the final say on whether a particular skill applies in a situation.

This gives us another important piece of game notation.

Instead of merely saying:

Wisdom Check

the rules might say:

Wisdom (Perception) Check

The ability is:

Wisdom

The skill is:

Perception

HOW TO READ AN ABILITY CHECK

Consider:

Strength (Athletics)

This means:

Ability being used: Strength

Relevant skill: Athletics

So you roll:

d20 + Strength Modifier

If you are proficient in Athletics, you also add:

your Proficiency Bonus

PROFICIENCY DOES NOT DETERMINE WHETHER YOU CAN TRY

This is one of the most important rules for beginners.

You normally do not need proficiency in a skill to attempt a check involving that skill.

If you lack the proficiency:

you can still make the check.

You simply do not add your Proficiency Bonus for that skill.

The SRD uses climbing a cliff as an example. A character making a Strength (Athletics) check adds Proficiency Bonus if proficient in Athletics; otherwise, the character still makes the check but without that bonus.

EXAMPLE — WITH PROFICIENCY

Suppose your character has:

Strength Modifier: +3

Proficiency Bonus: +2

and proficiency in:

Athletics

The GM asks for:

Strength (Athletics), DC 15

You roll:

11

Calculation:

11 + 3 + 2 = 16

Because:

16 ≥ 15

you succeed.

EXAMPLE — WITHOUT PROFICIENCY

Another character attempts the same challenge.

Their Strength Modifier is:

+3

but they do not have Athletics proficiency.

They roll:

11

Calculation:

11 + 3 = 14

No Proficiency Bonus is added.

Because:

14 < 15

the check fails.

The important point is that the second character was still allowed to attempt the check.

THE 18 SKILLS

The SRD contains 18 skills.

Each skill is associated with an ability that it most commonly uses.

However, the table describes the ability the skill most often applies to, and the GM determines which skill is relevant in the particular situation.

Here is the complete list.

ACROBATICS

Usually Dexterity

Acrobatics can be used to:

  • stay on your feet in a difficult situation

  • perform an acrobatic stunt

 

Typical notation:

Dexterity (Acrobatics)

ANIMAL HANDLING

Usually Wisdom

Animal Handling can be used to:

  • calm an animal

  • train an animal

  • get an animal to behave in a particular way

 

Typical notation:

Wisdom (Animal Handling)

ARCANA

Usually Intelligence

Arcana can be used to recall lore concerning:

  • spells

  • magic items

  • planes of existence

 

Typical notation:

Intelligence (Arcana)

ATHLETICS

Usually Strength

Athletics can be relevant when trying to:

  • jump farther than normal

  • remain afloat in rough water

  • break something

 

Typical notation:

Strength (Athletics)

DECEPTION

Usually Charisma

Deception can be used to:

  • tell a convincing lie

  • convincingly maintain a disguise

 

Typical notation:

Charisma (Deception)

HISTORY

Usually Intelligence

History can be used to recall lore about:

  • historical events

  • people

  • nations

  • cultures

 

Typical notation:

Intelligence (History)

INSIGHT

Usually Wisdom

Insight can help determine:

  • another person's mood

  • another person's intentions

 

Typical notation:

Wisdom (Insight)

INTIMIDATION

Usually Charisma

Intimidation can be used to:

  • awe someone

  • threaten someone into doing what you want

 

Typical notation:

Charisma (Intimidation)

INVESTIGATION

Usually Intelligence

Investigation can be used to:

  • find obscure information in books

  • deduce how something functions

 

Typical notation:

Intelligence (Investigation)

MEDICINE

Usually Wisdom

Medicine can be used to:

  • diagnose an illness

  • determine what killed someone who recently died

 

Typical notation:

Wisdom (Medicine)

NATURE

Usually Intelligence

Nature can be used to recall lore concerning:

  • terrain

  • plants

  • animals

  • weather

 

Typical notation:

Intelligence (Nature)

PERCEPTION

Usually Wisdom

Perception involves using the senses to notice something that could easily be missed.

Typical notation:

Wisdom (Perception)

Perception is particularly important during exploration.

Later lessons will show how it interacts with:

  • hiding

  • obscurement

  • searching

  • special senses

PERFORMANCE

Usually Charisma

Performance can involve:

  • acting

  • telling a story

  • performing music

  • dancing

 

Typical notation:

Charisma (Performance)

PERSUASION

Usually Charisma

Persuasion is used to honestly and graciously convince someone of something.

Typical notation:

Charisma (Persuasion)

RELIGION

Usually Intelligence

Religion can be used to recall lore concerning:

  • gods

  • religious rituals

  • holy symbols

 

Typical notation:

Intelligence (Religion)

SLEIGHT OF HAND

Usually Dexterity

Sleight of Hand can be relevant when attempting to:

  • pick someone's pocket

  • conceal a small handheld object

  • perform legerdemain

 

Typical notation:

Dexterity (Sleight of Hand)

STEALTH

Usually Dexterity

Stealth can be used to escape notice by:

  • moving quietly

  • hiding behind things

 

Typical notation:

Dexterity (Stealth)

The detailed Hide rules will be covered later in the course.

SURVIVAL

Usually Wisdom

Survival can be used to:

  • follow tracks

  • forage

  • find a trail

  • avoid natural hazards

 

Typical notation:

Wisdom (Survival)

COMPLETE SKILL REFERENCE

Skill Ability Most Often Used
Acrobatics Dexterity
Animal Handling Wisdom
Arcana Intelligence
Athletics Strength
Deception Charisma
History Intelligence
Insight Wisdom
Intimidation Charisma
Investigation Intelligence
Medicine Wisdom
Nature Intelligence
Perception Wisdom
Performance Charisma
Persuasion Charisma
Religion Intelligence
Sleight of Hand Dexterity
Stealth Dexterity
Survival Wisdom

 

SKILLS ARE NOT SEPARATE ABILITY SCORES

A skill is not a seventh, eighth, or nineteenth ability.

Skills operate through Ability Checks.

For example:

Perception does not replace Wisdom.

A typical Perception check is:

Wisdom (Perception)

You still use your:

Wisdom Modifier

Then, if you have Perception proficiency:

add your Proficiency Bonus.

THE ABILITY AND THE SKILL ARE TWO DIFFERENT PARTS

This distinction matters.

Take:

Dexterity (Stealth)

The Dexterity part tells you which Ability Modifier to use.

The Stealth part tells you which skill proficiency may apply.

So if you have:

Dexterity Modifier +3

and:

Proficiency Bonus +2

and you are proficient in Stealth:

you normally add:

+5 total

before any other applicable modifiers.

SKILLS ARE ASSOCIATED WITH ABILITIES, BUT THE GM DETERMINES RELEVANCE

The SRD's skill table identifies the ability that each skill most often uses rather than saying every use must always employ that ability. It also states that the GM has the ultimate say on whether a skill is relevant to a situation.

This means you should pay attention to the complete check the GM requests.

For example, a rule or GM might specify an unusual combination when the nature of the challenge makes that combination appropriate.

The relevant notation tells you exactly what to use.

MORE THAN ONE SKILL CAN SOMETIMES BE RELEVANT

The SRD itself gives an example of a check written as:

Strength (Acrobatics or Athletics)

In such a case, a character can add Proficiency Bonus if proficient in either of the named skills.

This illustrates an important idea:

A particular challenge may sometimes permit more than one relevant form of training.

The exact rule or GM instruction determines what applies.

WHERE DO YOUR SKILL PROFICIENCIES COME FROM?

For player characters, starting skill proficiencies are established during Character Creation.

Monster skill proficiencies appear in their stat blocks.

We will study how characters acquire their proficiencies later when we reach:

  • Character Creation

  • Classes

  • Backgrounds

For this lesson, you only need to understand what proficiency does once you have it.

TOOL PROFICIENCY AND ABILITY CHECKS

Skills are not the only kind of proficiency that can matter during an Ability Check.

A tool proficiency can also apply.

If you are proficient with a tool and make an Ability Check using that tool:

you can add your Proficiency Bonus.

But the SRD 5.2.1 adds an especially important interaction.

If:

the tool proficiency applies

and

you also have proficiency in the skill used for the same check

then you still add Proficiency Bonus only once, but you also gain:

ADVANTAGE ON THE CHECK

 

EXAMPLE — SKILL AND TOOL TOGETHER

Imagine the GM determines that a particular Ability Check involves:

  • an appropriate skill

  • a particular tool

Your character is proficient in both.

You do not add Proficiency Bonus twice.

Instead:

add Proficiency Bonus once

and:

make the check with Advantage

when both proficiencies apply as described by the SRD.

This distinction is important.

PROFICIENCY BONUS DOES NOT STACK

Even when more than one proficiency could apply, you don't normally add the same Proficiency Bonus multiple times.

The SRD explicitly states that Proficiency Bonus cannot be added to the same roll or number more than once.

So if two relevant proficiencies both apply:

do not simply double the bonus.

If a specific rule modifies Proficiency Bonus, such as Expertise, that operates according to its own rule.

We will study this in much more detail in Lesson 9.

DIFFICULTY CLASS — DC

Now we come to the target number for an Ability Check.

This target is called:

DIFFICULTY CLASS

or:

DC

The Difficulty Class represents how difficult the task is.

The harder the task:

the higher the DC.

THE STANDARD DC SCALE

The SRD provides the following typical Difficulty Classes:

Task Difficulty DC
Very Easy 5
Easy 10
Medium 15
Hard 20
Very Hard 25
Nearly Impossible 30

 

This scale gives the GM a reference for deciding how difficult an uncertain task should be.

DC 5 — VERY EASY

A task with:

DC 5

is considered:

Very Easy

A character with even modest bonuses will often have a strong chance of succeeding.

DC 10 — EASY

A:

DC 10

task is:

Easy

It is still uncertain enough to justify a check if failure matters, but it is not especially demanding.

DC 15 — MEDIUM

A:

DC 15

task represents:

Medium difficulty

This is a meaningful challenge.

DC 20 — HARD

A:

DC 20

task is:

Hard

A strong relevant modifier and useful proficiency can become especially important here.

DC 25 — VERY HARD

A:

DC 25

task is:

Very Hard

Success normally requires a strong combination of ability, training, and a favorable roll.

DC 30 — NEARLY IMPOSSIBLE

A:

DC 30

task represents something:

Nearly Impossible

It is an exceptional challenge.

WHO SETS THE DC?

Some rules already provide a specific DC.

In those situations:

use the DC stated by the rule.

When a rule does not provide one, the GM ultimately determines the Difficulty Class for the Ability Check.

The standard DC scale helps the GM make that decision.

A SIMPLE DC EXAMPLE

The GM decides that a challenge is:

Hard

Using the standard scale:

Hard = DC 20

The character makes the relevant Ability Check.

Suppose:

d20 roll = 15

Ability Modifier = +3

Proficiency Bonus = +2

Total:

20

Because:

20 = DC 20

the check succeeds.

Remember:

meeting the DC is enough.

ANOTHER EXAMPLE

The task has:

DC 15

The character rolls:

9

Ability Modifier:

+2

Proficiency Bonus:

+2

Total:

13

Because:

13 < 15

the check fails.

The GM then describes what that failure means in the current situation.

WHAT DOES FAILURE MEAN?

The Ability Check tells you whether the attempt succeeds against the target DC.

The exact consequences depend on the challenge and the situation.

Failure might mean that:

  • the immediate attempt doesn't work

  • the character fails to discover something

  • an opportunity is lost

  • the situation becomes more difficult

  • another consequence described by the rule or GM occurs

The important point from the SRD is that Ability Checks are used when failure is meaningful and the result is uncertain.

PLAY EXAMPLE — THE LOCKED DOOR

The party discovers a locked door.

PLAYER

“I try to open the lock.”

The GM determines that the attempt requires an Ability Check using an appropriate ability, skill, or tool according to the situation.

Suppose the final target is:

DC 15

The player rolls the d20 and applies the relevant modifiers.

If the total is:

17

success.

If the total is:

12

failure.

The GM narrates the consequence, and the game continues.

PLAY EXAMPLE — THE HIDDEN CLUE

The players enter an ancient chamber.

The GM knows there is something easy to overlook.

A character tries to notice it.

The GM may call for an Ability Check involving:

Wisdom (Perception)

The player uses:

d20 + Wisdom Modifier

and adds Proficiency Bonus if proficient in Perception.

The result is compared with the relevant DC.

PLAY EXAMPLE — UNDERSTANDING AN ANCIENT TEXT

A character examines information concerning a forgotten civilization.

Depending on exactly what the character is attempting, the GM may determine that an Intelligence-based skill is relevant.

For example:

Intelligence (History)

The character rolls:

d20 + Intelligence Modifier

and, if proficient in History:

+ Proficiency Bonus

The total is compared with the DC.

PLAY EXAMPLE — CONVINCING SOMEONE

A character wants to honestly convince another creature of something.

If an Ability Check is necessary and the appropriate skill is Persuasion, the GM might call for:

Charisma (Persuasion)

The character rolls:

d20 + Charisma Modifier

plus Proficiency Bonus if proficient in Persuasion.

Social interaction has additional rules that we will cover in:

Lesson 12.

CHOOSING THE RIGHT CHECK

When considering an Ability Check, think in this order:

FIRST — WHAT IS THE CHARACTER TRYING TO DO?

Understand the action in the fictional situation.

SECOND — WHICH ABILITY BEST REPRESENTS THE CHALLENGE?

Strength?

Dexterity?

Constitution?

Intelligence?

Wisdom?

Charisma?

THIRD — IS A SKILL RELEVANT?

If so, identify the appropriate skill.

FOURTH — DOES THE CHARACTER HAVE THAT PROFICIENCY?

If yes, add Proficiency Bonus.

FIFTH — DOES A TOOL ALSO APPLY?

If a relevant tool proficiency is involved, its rules may also affect the check.

SIXTH — WHAT IS THE DC?

Use a DC provided by the rules or one determined by the GM.

FINALLY — ROLL

Roll the D20 Test and resolve the result.

THE ABILITY CHECK IN ONE FORMULA

A common Ability Check can be represented as:

1d20

+ Relevant Ability Modifier

+ Proficiency Bonus, if relevant

+ Other applicable modifiers

= Ability Check Total

Then compare:

Ability Check Total vs. DC

If:

Total ≥ DC

SUCCESS

If:

Total < DC

FAILURE

COMMON BEGINNER MISTAKES

MISTAKE 1 — ADDING THE ABILITY SCORE

If you have:

Wisdom 16

you do not normally add:

+16

to the check.

Wisdom 16 gives:

Wisdom Modifier +3

That is the number normally used.

MISTAKE 2 — ADDING PROFICIENCY TO EVERYTHING

Proficiency Bonus does not automatically apply to every Ability Check.

It applies when a relevant skill or tool proficiency is involved and you have that proficiency.

MISTAKE 3 — THINKING YOU CAN'T TRY WITHOUT PROFICIENCY

You can normally make a check involving a skill even if you lack proficiency in that skill.

You simply don't receive the Proficiency Bonus from that skill.

MISTAKE 4 — ADDING PROFICIENCY TWICE

If two relevant proficiencies apply, that does not normally mean you simply add Proficiency Bonus twice.

The bonus itself doesn't stack.

MISTAKE 5 — ASSUMING EVERY ACTION REQUIRES A CHECK

Ability Checks are for situations where the result is uncertain and failure is meaningful.

Do not turn every ordinary action into a die roll.

MISTAKE 6 — THINKING THE SKILL DEFINES THE ENTIRE CHECK

The check still uses an Ability Modifier.

For example:

Wisdom (Perception)

means:

Wisdom determines the Ability Modifier.

Perception determines whether that skill proficiency applies.

LESSON 5 — KEY TAKEAWAYS

ABILITY CHECKS RESOLVE CHALLENGES

They are used when a creature tries to overcome an uncertain challenge, especially when failure has meaningful consequences.

EVERY CHECK USES AN ABILITY

The six possibilities are:

Strength

Dexterity

Constitution

Intelligence

Wisdom

Charisma

MOST ABILITY CHECKS INVOLVE A SKILL

There are 18 skills in the SRD:

Acrobatics

Animal Handling

Arcana

Athletics

Deception

History

Insight

Intimidation

Investigation

Medicine

Nature

Perception

Performance

Persuasion

Religion

Sleight of Hand

Stealth

Survival

SKILLS HAVE COMMON ABILITY ASSOCIATIONS

For example:

Athletics → usually Strength

Stealth → usually Dexterity

Arcana → usually Intelligence

Perception → usually Wisdom

Persuasion → usually Charisma

But the complete check specified by the rule or GM tells you what ability and skill apply.

PROFICIENCY ADDS YOUR PROFICIENCY BONUS

If you have proficiency in the relevant skill:

add your Proficiency Bonus.

If you lack that proficiency:

you can normally still make the check.

TOOLS CAN ALSO APPLY

Tool proficiency can allow you to add Proficiency Bonus to an Ability Check using the tool.

If a relevant skill proficiency and relevant tool proficiency both apply to the same check, the SRD says you also have Advantage on that check.

PROFICIENCY BONUS DOESN'T STACK

You don't simply add the same Proficiency Bonus multiple times to one roll.

DC MEASURES DIFFICULTY

Typical DCs are:

Very Easy — 5

Easy — 10

Medium — 15

Hard — 20

Very Hard — 25

Nearly Impossible — 30

MEETING THE DC SUCCEEDS

If:

Ability Check Total ≥ DC

the check succeeds.

NEXT LESSON

LESSON 6 — SAVING THROWS: RESISTING THREATS, HAZARDS, AND EFFECTS

Ability Checks usually represent something your character is actively trying to accomplish.

Saving Throws are different.

A Saving Throw is generally made because something dangerous is happening to you.

In Lesson 6, we will learn:

  • what a Saving Throw represents

  • when a save is required

  • the six types of Saving Throw

  • what Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma saves resist

  • how Saving Throw proficiency works

  • how the save's Difficulty Class is determined

  • how spells and monster abilities establish their DCs

  • when a creature can choose to fail a Saving Throw

This will give us the second major form of D20 Test.

SRD 5.2.1 ATTRIBUTION

This work includes material from the System Reference Document 5.2.1 (“SRD 5.2.1”) by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.