Apostrophe Rules: Uses, Examples, and Common Mistakes

Apostrophe rules can feel confusing because the same tiny punctuation mark performs several different jobs. You may know that apostrophes show possession, but why do we write the student’s book, the students’ books, and the children’s books differently? And why does it’s contain an apostrophe when its shows possession?

The good news is that you do not need to memorize dozens of unrelated instructions. Most apostrophe mistakes disappear once you understand whether the word shows possession, contains missing letters, or is simply plural.

Quick answer: Use an apostrophe to show possession, mark missing letters or numbers, and form a few special plurals when clarity requires it. Do not normally use an apostrophe simply to make a word plural.

Table of Contents

What Are the Main Apostrophe Rules?

The three main apostrophe rules are:

Use an apostrophe to show possession.
Use an apostrophe where letters or numbers have been omitted.
Use an apostrophe in a few unusual plurals when it prevents confusion.

The most important warning is equally simple:

Do not add an apostrophe just because a word ends in s.

Compare these examples:

Correct: three dogs
Incorrect: three dog’s
Correct: several laptops
Incorrect: several laptop’s
Correct: the dog’s collar
Correct: the laptops’ screens

The Purdue Online Writing Lab also identifies possession and omitted letters as the apostrophe’s principal uses.

Apostrophe Rules at a Glance

Situation	Rule	Example
Singular noun	Add ’s	the student’s book
Singular noun ending in s	Usually add ’s	James’s laptop
Regular plural ending in s	Add only ’	the students’ books
Irregular plural not ending in s	Add ’s	the children’s room
Contraction	Place the apostrophe where letters are missing	don’t, it’s, they’re
Ordinary plural	Do not use an apostrophe	books, phones, teachers
Possessive pronoun	Do not use an apostrophe	its, yours, hers, theirs
Omitted numbers	Use an apostrophe for the missing numbers	the class of ’26
Lowercase-letter plural	Use an apostrophe when clarity requires it	mind your p’s and q’s

The Rule in One Sentence

Use an apostrophe for possession or omitted letters, not for an ordinary plural.

That single sentence summarizes the most important apostrophe rules and prevents many common errors.

What Is an Apostrophe?

An apostrophe is the punctuation mark that looks like this:

’

It appears near the top of a letter and should not be confused with a comma, which sits near the bottom of a line.

You will commonly see apostrophes in expressions such as:

Sarah’s notebook
can’t
we’re
two weeks’ notice
the class of ’26
mind your p’s and q’s

Depending on the sentence, the apostrophe may show possession, replace missing letters, or make an unusual plural easier to understand.

Apostrophe Rules for Singular Possessive Nouns

A possessive form shows ownership, association, origin, connection, or another close relationship.

For most singular nouns, add an apostrophe followed by s.

Pattern

singular noun + ’s

Examples

the student’s essay
the manager’s office
the child’s backpack
the restaurant’s menu
my brother’s car
the computer’s screen

Examples in sentences

The student’s essay was carefully researched.
We waited outside the manager’s office.
The restaurant’s menu changes every season.
My brother’s car needs a new battery.
The computer’s screen suddenly went dark.

These apostrophe rules apply whether the singular noun refers to a person, animal, organization, place, object, or idea.

Possession does not always mean literal ownership. A day cannot own anything, but today’s meeting means the meeting associated with today.

Apostrophe Rules for Singular Nouns Ending in S

A singular noun or name that already ends in s usually still takes ’s.

Examples

the boss’s office
the class’s schedule
the bus’s engine
the glass’s edge
James’s laptop
Chris’s jacket

In sentences

The boss’s office is at the end of the hall.
Our class’s schedule changed this morning.
The bus’s engine made a strange noise.
I found James’s laptop on the table.
Chris’s jacket is hanging by the door.

For general American English, Grammar Flare recommends:

James’s book
Chris’s phone
the boss’s decision
the class’s results

Some journalistic and organizational styles prefer James’ or Chris’. The Chicago Manual of Style generally recommends adding ’s to singular nouns, including most singular names ending in s.

The most important point is consistency. Follow the style required by your school, employer, journal, or publisher.

Plural Possessive Nouns Ending in S

When a plural noun already ends in s, add only an apostrophe after the final s.

Pattern

plural noun ending in s + ’

Examples

the students’ books
the teachers’ lounge
the dogs’ bowls
the customers’ complaints
the players’ uniforms
my parents’ house

In sentences

The students’ books were stacked near the window.
The meeting took place in the teachers’ lounge.
We washed the dogs’ bowls.
The company responded to the customers’ complaints.
The players’ uniforms arrived yesterday.
We spent the weekend at my parents’ house.

Compare

the student’s book: the book belongs to one student
the students’ books: the books belong to multiple students

The location of the apostrophe changes the meaning.

Irregular Plural Possessive Nouns

Some plural nouns do not end in s. Add ’s to make these irregular plural nouns possessive.

Examples

children’s toys
women’s clothing
men’s shoes
people’s opinions
mice’s nests
geese’s feathers

In sentences

The store sells children’s clothing.
We discussed people’s reactions.
The women’s team reached the final.
The men’s changing room is downstairs.
The researcher studied the mice’s behavior.

Singular	Plural	Plural possessive
child	children	children’s
woman	women	women’s
man	men	men’s
person	people	people’s
mouse	mice	mice’s

Explore more irregular forms in Grammar Flare’s Plural Nouns guides.

Joint Possession and Separate Possession

Apostrophe placement can show whether two people share something or own separate things.

Joint possession

When two people share one thing, add ’s only to the final name.

Mia and Noah’s apartment
Alex and Jordan’s business
Sam and Priya’s wedding
my mother and father’s house

Examples

We visited Mia and Noah’s apartment.
Alex and Jordan’s business opened last year.
I received an invitation to Sam and Priya’s wedding.

Only one apartment, business, or wedding is involved.

Separate possession

When each person owns a separate thing, make both names possessive.

Mia’s and Noah’s apartments
Alex’s and Jordan’s offices
Sam’s and Priya’s schedules

Examples

Mia’s and Noah’s apartments are in different neighborhoods.
Alex’s and Jordan’s offices are on separate floors.
We compared Sam’s and Priya’s schedules.

Possessives With Compound Nouns

Place the apostrophe at the end of the complete compound expression.

Correct examples

my mother-in-law’s recipe
the editor in chief’s decision
someone else’s problem
the post office’s opening hours
the attorney general’s statement

In sentences

This is my mother-in-law’s recipe.
We are waiting for the editor in chief’s decision.
Do not take someone else’s phone.
The post office’s opening hours changed.

Avoid placing the apostrophe in the middle.

Correct: mother-in-law’s
Incorrect: mother’s-in-law
Correct: someone else’s
Incorrect: someone’s else

Apostrophe Rules for Contractions

A contraction combines two words by removing one or more letters. The apostrophe marks the place where those letters are missing.

Full form	Contraction
do not	don’t
cannot	can’t
is not	isn’t
will not	won’t
I am	I’m
I will	I’ll
you are	you’re
they are	they’re
we have	we’ve
who is	who’s
it is	it’s

Examples

I don’t understand the question.
She can’t attend the meeting.
You’re doing a great job.
They’re waiting outside.
We’ve already finished.
Who’s responsible for the report?
It’s going to rain.

The apostrophe does not simply appear before the final s. It replaces omitted letters.

do not → don’t
you are → you’re
they are → they’re
it is → it’s
who is → who’s

Contractions That Commonly Cause Confusion

It’s vs. its

it’s means it is or it has
its is the possessive form of it

Examples:

It’s getting late.
It’s been a busy week.
The company changed its policy.

Use the expansion test. Replace the word with it is or it has. If the sentence still makes sense, use it’s.

Read the complete Grammar Flare guide to It’s vs. Its. You can also compare the explanation from Merriam-Webster.

Who’s vs. whose

who’s means who is or who has
whose shows possession

Examples

Who’s coming with us?
Who’s completed the assignment?
Whose bag is this?

Read Who’s vs. Whose for more examples.

You’re vs. your

you’re means you are
your shows possession

Examples

You’re welcome.
You’re doing well.
Is this your notebook?

See the complete guide to Your vs. You’re.

They’re vs. their vs. there

they’re means they are
their shows possession
there refers to a place or introduces a sentence

Examples

They’re waiting outside.
Their car is parked nearby.
Put the box over there.

Do Not Use Apostrophes for Ordinary Plurals

One of the most important apostrophe rules is that ordinary plurals normally do not need apostrophes.

To make most nouns plural, add s or es.

Correct plurals

books
phones
teachers
students
computers
apples
restaurants
videos
emails
weekends

Incorrect plurals

book’s
phone’s
teacher’s
student’s
computer’s
apple’s
restaurant’s
video’s
email’s
weekend’s

Compare these forms

Form	Meaning
book	one book
books	more than one book
book’s	belonging to one book
books’	belonging to multiple books

Examples

I bought three books.
The book’s cover was damaged.
The books’ covers were damaged.

Do Not Use Apostrophes in Decade Plurals

Use a plain s to make a decade plural.

Correct

the 1980s
the 1990s
the early 2000s
music from the 1960s

Incorrect

the 1980’s
the 1990’s
the 2000’s
the 1960’s

Use an apostrophe only when numbers have been omitted.

Correct shortened forms

the class of ’26
music from the ’90s
the election of ’08

In ’90s, the apostrophe replaces the missing 19. The final s makes the decade plural.

Apostrophe Rules for Family Names

Do not use an apostrophe simply to pluralize a last name.

Correct plural names

the Smiths
the Johnsons
the Parkers
the Joneses
the Martinezes

Incorrect plural names

the Smith’s
the Johnson’s
the Parker’s
the Jones’
the Martinez’s

For most names, add s:

Smith → Smiths
Parker → Parkers
Johnson → Johnsons

For names ending in s, x, z, ch, or sh, you will often add es:

Jones → Joneses
Martinez → Martinezes
Bush → Bushes

Add an apostrophe only when the plural family name becomes possessive:

the Smiths’ house
the Johnsons’ car
the Joneses’ invitation
the Martinezes’ garden

Possessive Pronouns Do Not Take Apostrophes

Possessive pronouns and possessive determiners already express possession. They do not need apostrophes.

Correct forms

his
hers
its
ours
yours
theirs
whose

Examples

That jacket is hers.
The final decision is yours.
The company changed its website.
The victory was theirs.
Whose keys are these?

Incorrect forms

her’s
your’s
our’s
their’s
its’
whose’

These are not standard English forms.

A useful memory trick is:

If a possessive word already works by itself, do not add an apostrophe.

Apostrophe Rules for Time and Measurement

Use possessive forms in many expressions involving time, value, and measurement.

Singular expressions

a day’s work
an hour’s delay
a week’s vacation
a dollar’s worth
a moment’s silence

Plural expressions

two days’ work
three hours’ delay
two weeks’ notice
five years’ experience
ten dollars’ worth

Examples

I completed a day’s work before lunch.
The train experienced an hour’s delay.
Please give us two weeks’ notice.
She has five years’ experience in marketing.
We bought ten dollars’ worth of snacks.

Compare

one week’s notice
two weeks’ notice

Apostrophes in Academic Degrees

Write

bachelor’s degree
master’s degree

Examples

She earned a bachelor’s degree in biology.
He is completing a master’s degree in education.

Do not use an apostrophe in formal degree names or abbreviations

Bachelor of Science
Master of Arts
BS
BA
MS
MA

Read Grammar Flare’s guide to Bachelor Degree or Bachelor’s Degree.

Apostrophes With Letters and Numbers

Apostrophes may be used to pluralize individual lowercase letters when doing so prevents confusion.

Examples

Mind your p’s and q’s.
The word accommodate contains two c’s and two m’s.
Remember to dot your i’s and cross your t’s.

Many modern styles prefer a plain s with capital letters and numbers when the result is clear:

She earned three As.
The password contains two 7s.
The player scored several 3s.
The document contains four URLs.

Follow the style guide required for your work and remain consistent.

Common Apostrophe Mistakes

Adding apostrophes to ordinary plurals

Incorrect

We sell fresh apple’s.
The student’s are waiting.
I received several email’s.

Correct

We sell fresh apples.
The students are waiting.
I received several emails.

Forgetting an apostrophe in a possessive

Incorrect

The teachers desk is near the window.
Sarah phone is ringing.
The company policy changed.

Correct

The teacher’s desk is near the window.
Sarah’s phone is ringing.
The company’s policy changed.

Putting the apostrophe in the wrong place

Incorrect

the student’s books, when the books belong to several students
the childrens’ room
my parent’s house, when referring to both parents

Correct

the students’ books
the children’s room
my parents’ house

Adding apostrophes to possessive pronouns

Incorrect

The choice is your’s.
The dog hurt it’s leg.
The responsibility is their’s.

Correct

The choice is yours.
The dog hurt its leg.
The responsibility is theirs.

Confusing contractions with possessives

Incorrect

Its going to rain.
The company changed it’s logo.
Whose attending the meeting?

Correct

It’s going to rain.
The company changed its logo.
Who’s attending the meeting?

A Fast Method for Checking Apostrophes

These apostrophe rules become much easier when you ask three questions.

Does the word show possession?

Ask who or what owns, uses, or is associated with the noun.

the student’s laptop
the students’ laptops
the children’s laptops

Then decide whether the owner is singular, a regular plural, or an irregular plural.

Are letters or numbers missing?

Try expanding the expression.

it’s → it is or it has
you’re → you are
who’s → who is or who has
didn’t → did not
’90s → 1990s

If the longer form works, the apostrophe marks an omission.

Is the word simply plural?

If the word only means more than one, it probably does not need an apostrophe.

books
students
phones
videos
1990s
Smiths

Apostrophe Examples in Everyday Writing

Emails

I’ve attached today’s meeting notes.
Please send the client’s revised document.
We need two days’ notice before cancellation.
You’re welcome to suggest changes.

School writing

The author’s argument becomes clearer in the final chapter.
The students’ results were compared.
Shakespeare’s plays remain widely studied.
The children’s responses were recorded.

Business writing

The company’s revenue increased.
The employees’ concerns were discussed.
The manager’s decision will be announced tomorrow.
It’s important to review the contract.

Social media

Here are this week’s highlights.
We’re celebrating our customers’ stories.
It’s finally Friday.
The team’s new video is online.

Signs and advertisements

Correct

Fresh apples
Customers’ entrance
Men’s clothing
Women’s shoes
Children’s books

Incorrect

Fresh apple’s
Customer’s entrance, when intended for all customers
Mens clothing
Womens shoes
Childrens books

Mini Quiz: Test Your Knowledge

1. The two ___ projects were displayed.

A. student’s
B. students’
C. students

2. ___ going to be a long day.

A. Its
B. It’s
C. Its’

3. The company changed ___ policy.

A. it’s
B. its
C. its’

4. We need three ___ notice.

A. days
B. day’s
C. days’

5. The ___ toys were scattered across the floor.

A. childrens
B. children’s
C. childrens’

6. Happy holidays from the ___.

A. Smith’s
B. Smiths
C. Smiths’

7. We visited the ___ new house.

A. Smiths
B. Smith’s
C. Smiths’

8. ___ jacket is hanging by the door?

A. Who’s
B. Whose
C. Whos’

9. I found ___ phone on the desk.

A. James
B. James’s
C. Jameses

10. She earned two ___ in her final exams.

A. A’s
B. As
C. Either may be accepted depending on style

Quiz Answers

B: students’ — The projects belong to multiple students.
B: It’s — The sentence means It is going to be a long day.
B: its — Its is the possessive form.
C: days’ — The notice covers multiple days.
B: children’s — Children is an irregular plural.
B: Smiths — The family name is simply plural.
C: Smiths’ — The house belongs to the Smith family.
B: Whose — The question asks about possession.
B: James’s — James is one person.
C — Many modern styles prefer As, while some use A’s for clarity.

Frequently Asked Questions About Apostrophe Rules

What are the basic apostrophe rules?

Use apostrophes to show possession, mark missing letters or numbers, and form a few special plurals when clarity requires them. Do not use an apostrophe to create an ordinary plural.

How do I know whether the apostrophe goes before or after the s?

Place the apostrophe before the s for a singular possessive or an irregular plural possessive:

the teacher’s desk
the children’s room

Place the apostrophe after the s for a regular plural possessive:

the teachers’ desks
the students’ room

Is it James’s or James’?

Both appear in edited writing. Grammar Flare recommends James’s for general American English because James is singular.

Is it students or student’s?

Use students for more than one student. For Example: The students arrived.

Use student’s when something belongs to one student.

The student’s bag is missing.

Use students’ when something belongs to multiple students.

The students’ bags are outside.

Do decades need apostrophes?

Ordinary decade plurals do not:

the 1980s
the 1990s

Use an apostrophe when numbers are omitted:

the class of ’26
music from the ’90s

Do family names need apostrophes?

Not when you are simply making the name plural.

the Smiths
the Joneses

Use an apostrophe to show possession.

the Smiths’ house
the Joneses’ car

Is its’ ever correct?

No. Its’ is not a standard English form.

Use

it’s for it is or it has
its for possession

Why does its not have an apostrophe?

Its follows the same pattern as his, hers, yours, ours, and theirs. These possessive forms do not use apostrophes.

Related Grammar Flare Guides

Final Takeaway

The essential apostrophe rules are easier to remember when you identify the apostrophe’s job.

Add ’s to most singular possessive nouns.
Add only ’ to regular plural possessive nouns ending in s.
Add ’s to irregular plural possessive nouns.
Use apostrophes to mark missing letters or numbers.
Do not use apostrophes for ordinary plurals.
Do not add apostrophes to its, yours, hers, ours, or theirs.f

When you are unsure, ask whether the word shows possession, contains missing letters, or simply means more than one. That quick check will solve most apostrophe problems.

Grammar Flare Editorial Team