Theirs or Their’s: What’s the Correct Usage?

Theirs or Their’s? is a common grammar question about ownership, possessive pronouns, apostrophes, and the correct spelling in standard English.

When describing ownership, choosing between theirs and their’s often creates confusion for beginners and intermediate learners. Both words have similar forms, but standard English recognizes only theirs as the correct spelling. It works as one of the possessive pronouns that expresses possession when something belongs to another person. The word doesn’t need an apostrophe to show possession. Understanding this grammar difference helps prevent spelling mistakes and grammar mistakes in everyday writing.

The possessive forms of English follow different grammar rules, including a special possessive rule for theirs. Many writers add apostrophes because they associate them with ownership. Words such as their and they’re have separate meanings, so learning to distinguish them improves correct usage. My experience with English writing shows that checking these words before completing a sentence can prevent unnecessary errors. Using the correct form makes communication easier in school assignments, workplace emails, essays, social media posts, and everyday conversations.

Correctly using theirs helps you with writing clearly and developing stronger professional writing skills. Accurate English grammar matters in emails and academic work because it builds credibility and supports avoiding confusion. Although their’s appears among commonly confused words and commonly searched words, it remains an incorrect spelling in standard usage. Remember that theirs is a complete possessive pronoun. Adding an extra apostrophe makes the spelling incorrect.

Table of Contents

Theirs or Their’s: Quick Answer

Theirs is correct. Their’s is incorrect in standard English.

The word theirs is a possessive pronoun that means “belonging to them.” It indicates ownership without repeating the name of the person, group, or thing being discussed. Standard English does not use an apostrophe in this pronoun.

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Consider these examples:

Correct: The blue backpack is theirs.
Incorrect: The blue backpack is their’s.
Correct: Our classroom is upstairs, but theirs is downstairs.
Incorrect: Our classroom is upstairs, but their’s is downstairs.

Here’s a quick comparison:

Word	Correct spelling?	Meaning or use
Theirs	Yes	Shows that something belongs to them
Their’s	No	Incorrect spelling of the possessive pronoun
Their	Yes	Shows ownership before a noun
They’re	Yes	Contraction of “they are”

Remember: Possessive pronouns such as mine, yours, his, hers, ours, and theirs do not need apostrophes.

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What Does Theirs Mean?

Definition of Theirs

Theirs is a possessive pronoun that indicates ownership or a relationship with someone or something. It commonly refers to two or more people, but it can also refer to one person when you use singular they.

Meaning, Spelling & Use+1

In simple terms, theirs means belonging to them.

For example:

Those bicycles are theirs.
The final decision was theirs.
This garden is theirs, not ours.
Someone left a jacket here. I think it’s theirs.

In each sentence, theirs identifies ownership without requiring you to repeat a noun phrase.

Imagine that two students have separate notebooks. One notebook belongs to you, while the other belongs to your classmates. Instead of saying, “This is my notebook, and that is my classmates’ notebook,” you can write, “This is my notebook, and that one is theirs.”

The second sentence sounds more natural because theirs avoids unnecessary repetition.

Examples of Theirs in Sentences

The word theirs works in many everyday situations. You can use it to discuss personal belongings, shared responsibilities, decisions, and abstract ideas.

Example sentence	What theirs refers to
That red bicycle is theirs.	The bicycle belongs to them.
Our presentation is finished, but theirs needs editing.	Their presentation
The final choice was theirs.	Their choice
This room is ours, and the room next door is theirs.	The room next door
The responsibility is theirs.	Their responsibility
That opinion is theirs to express.	Their opinion

Notice that theirs can refer to physical objects and abstract concepts. Ownership doesn’t always involve something you can touch. It can also involve a decision, responsibility, idea, or right.

When to Use Theirs

Use theirs when you want to show ownership without placing a noun directly after the word.

For example:

Using their: Their house has a large garden.
Using theirs: Their house has a large garden, and ours has a small yard.

In the first sentence, their introduces the noun house. In the second, theirs stands in for a noun phrase that the reader can understand from context.

This distinction is useful when you want to avoid repetition. It also helps you build clearer sentences in essays, reports, and everyday writing.

What Does Their’s Mean?

Is Their’s a Real Word?

Their’s is not the standard spelling of the possessive pronoun. In edited English, use theirs without an apostrophe.

People often write their’s because they associate apostrophes with ownership. For instance, Maria’s book means the book belongs to Maria. Similarly, the dog’s collar indicates that the collar belongs to the dog.

However, English doesn’t apply this pattern to every possessive form. Words such as mine, yours, and theirs already express possession. Adding an apostrophe creates a spelling error rather than a correct possessive form.

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Compare these examples:

Incorrect: The winning team celebrated their’s victory.
Correct: The winning team celebrated their victory.
Incorrect: The last slice of cake is their’s.
Correct: The last slice of cake is theirs.

Notice that the correct choice depends on sentence structure. Use their before a noun, as in their victory. Use theirs when the possessive pronoun stands in for the noun phrase, as in the cake is theirs.

Why Do People Write Their’s?

The confusion comes from a rule that works in many other situations. English often uses an apostrophe plus s to show that a noun possesses something.

For example:

David’s laptop: The laptop belongs to David.
The teacher’s desk: The desk belongs to the teacher.
The dog’s bowl: The bowl belongs to the dog.

After learning these patterns, you might assume that their’s follows the same rule. That assumption makes sense at first glance, but possessive pronouns work differently.

Think of theirs as a complete word with its own spelling. It doesn’t need another punctuation mark to show ownership. The same principle applies to ours, yours, and hers.

Incorrect Examples of Their’s

The easiest way to learn the difference is to compare common mistakes with their corrections.

Incorrect sentence	Correct sentence
That house is their’s.	That house is theirs.
The blue bags are their’s.	The blue bags are theirs.
Our project is complete, but their’s isn’t.	Our project is complete, but theirs isn’t.
This responsibility is their’s alone.	This responsibility is theirs alone.
The final decision was their’s.	The final decision was theirs.

Each corrected sentence removes the unnecessary apostrophe. The meaning remains the same.

A useful editing tip: Search your document for their’s before submitting an essay or sending a professional email. Replacing it with theirs will usually fix the mistake when you’re expressing ownership.

Why Theirs Does Not Need an Apostrophe

Possessive Pronouns Do Not Use Apostrophes

Apostrophes have two common jobs in English: they can indicate possession with nouns, and they can mark omitted letters in contractions. However, possessive pronouns don’t require apostrophes.

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Here are the standard possessive pronouns:

Mine: This notebook is mine.
Yours: Is that jacket yours?
His: The seat by the window is his.
Hers: The red umbrella is hers.
Ours: The house at the corner is ours.
Theirs: The garden behind the fence is theirs.

You wouldn’t normally write your’s, her’s, or our’s. For the same reason, you shouldn’t write their’s.

A simple way to remember the rule is to treat these words as a family. Once you learn the correct spelling of one, the others become easier to remember.

The Difference Between Possessive Nouns and Possessive Pronouns

This distinction explains why teacher’s can be correct while their’s is not.

A possessive noun uses a noun to identify who owns something. A possessive pronoun expresses ownership without repeating the noun.

Possessive noun	Possessive pronoun
Emma’s notebook	The notebook is hers.
The students’ classroom	The classroom is theirs.
My brother’s bicycle	The bicycle is his.
Our parents’ house	The house is ours.
The coach’s decision	The decision is his or hers, depending on the context.

The apostrophe in Emma’s notebook marks possession because Emma is a noun. In the notebook is hers, the pronoun hers already indicates ownership.

One detail matters here: plural nouns that end in s generally take an apostrophe after that letter to show possession. For example, the students’ classroom indicates a classroom associated with multiple students. The pronoun theirs follows a different spelling rule.

The Difference Between Their, Theirs, and They’re

These three words sound alike in many varieties of English, but they serve different grammatical purposes. Choosing the right one depends on what your sentence needs.

Their

A possessive determiner used before a noun.

Example: Their dog loves playing outside.

Theirs

A possessive pronoun that stands in for a noun phrase.

Example: That dog is theirs.

They’re

A contraction of “they are.”

Example: They’re playing outside.

You can check they’re by replacing it with they are. If the sentence still makes sense, the contraction may be correct.

For example, “They’re ready for lunch” means “They are ready for lunch.” However, “The lunch is theirs” expresses ownership, so theirs is the right choice.

The words their and theirs are not interchangeable in every sentence, either. You write “their books” because their comes before the noun books. You write “the books are theirs” because theirs replaces the longer phrase their books.

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Theirs vs. Their’s: Key Differences

The main difference between theirs and their’s is the apostrophe. One follows standard English spelling rules, while the other does not.

Spelling and Grammar

The correct form is always theirs when you need the possessive pronoun. You don’t add an apostrophe, even when the word appears at the end of a sentence.

Consider these examples:

Correct: The responsibility is theirs.
Incorrect: The responsibility is their’s.
Correct: The winning idea was theirs.
Incorrect: The winning idea was their’s.

The rule stays the same in questions, statements, and longer sentences. You don’t need to adjust the spelling based on formality, sentence length, or the number of people who own something.

Meaning and Usage

Both forms usually appear in sentences where the writer intends to express ownership. However, only theirs is the accepted spelling for that purpose.

For example, imagine two neighbors sharing a garden. You might say, “The garden on the left is ours, and the garden on the right is theirs.” The pronoun theirs identifies the other neighbors as the owners.

Writing their’s would not change the intended meaning, but it would introduce a spelling error. Readers would probably understand your message, yet correct spelling makes your writing clearer and more polished.

Formal and Informal Writing

Theirs is correct in every standard writing style. You can use it in academic essays, business reports, emails, text messages, and casual conversations.

The incorrect form their’s doesn’t become acceptable simply because you’re writing informally. Although people sometimes use nonstandard spellings in online conversations, standard spelling remains the best choice when you want clear, accurate writing.

Common Mistakes to Avoid

Small spelling mistakes can slip into otherwise excellent writing. Fortunately, you can avoid the most common errors by learning a few simple distinctions.

Adding an apostrophe to theirs: Write “The seats are theirs,” not “The seats are their’s.”
Confusing their with theirs: Write “Their car is outside,” but “The car is theirs.”
Confusing theirs with they’re: Write “They’re coming to dinner” when you mean “They are coming to dinner.”
Applying noun rules to pronouns: Write “The teacher’s book” but “The book is hers.”
Assuming ownership always requires an apostrophe: Remember that possessive pronouns already express ownership.

A Quick Correction Table

Incorrect	Correct
Is that their’s?	Is that theirs?
Their’s was the better answer.	Theirs was the better answer.
They’re house is large.	Their house is large.
The project is their’s.	The project is theirs.
That idea is her’s.	That idea is hers.

These corrections follow the same basic principles of standard English possessive forms. For further guidance, see the British Council’s guide to possessive pronouns.

Theirs or Their’s? Examples in Everyday Writing

Seeing theirs in different contexts makes the rule easier to apply. The following examples show how the word works in everyday communication.

Examples in Academic Writing

Students often use possessive pronouns to compare assignments, research, opinions, or results.

My essay discusses climate change, while theirs examines renewable energy.
Our research project is complete, but theirs needs another review.
The final interpretation was theirs to explain.
Your answer differs from theirs.
The responsibility for checking the sources is theirs.

In each example, theirs replaces a noun phrase that the reader can identify from context. This makes the sentence shorter without losing its meaning.

Examples in Workplace Communication

Professional writing benefits from precise grammar, especially when you discuss tasks, reports, and shared responsibilities.

Our department finished its report, but theirs needs additional data.
The final approval is theirs to provide.
The presentation slides are ours, while the financial projections are theirs.
We completed our section, and they completed theirs.

The last example uses theirs to replace their section. This is a natural way to avoid repeating the same noun.

Examples in Everyday Conversation

You don’t need complicated sentences to use theirs correctly. Ordinary conversations provide plenty of opportunities.

Those keys are theirs.
The seats near the window are theirs.
Our dog is friendly, but theirs is shy.
I brought my lunch, and they brought theirs.
This umbrella isn’t ours. It’s theirs.

These examples show that theirs can refer to one item, several items, or something understood from an earlier sentence.

Theirs vs. Other Possessive Pronouns

Understanding related pronouns makes it easier to remember why theirs doesn’t need an apostrophe.

Possessive pronoun	Example
Mine	The blue notebook is mine.
Yours	This seat is yours.
His	The black jacket is his.
Hers	The red bicycle is hers.
Ours	The house near the park is ours.
Theirs	The apartment upstairs is theirs.

Each pronoun expresses ownership without requiring a noun immediately after it. Notice that none of these standard forms contains an apostrophe.

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Also, theirs can refer to a single person when you use singular they. For example, “Alex said the blue backpack was theirs.” The pronoun refers to Alex, not necessarily to multiple people.

How to Remember the Correct Spelling

A simple memory trick can save you from repeatedly checking the same grammar rule.

Use the Possessive Pronoun Rule

Remember this group of words:

Mine, yours, his, hers, ours, theirs.

These possessive pronouns don’t take apostrophes. If you remember the group, you’ll have an easy reference whenever you’re unsure about theirs or their’s.

Try the Replacement Test

When you aren’t sure whether to use their or theirs, check whether a noun follows the word.

Their + noun: Their house is near the school.
Theirs without a following noun: The house is theirs.

You can also mentally replace theirs with “belonging to them” to check the intended meaning.

For example, “The final decision is theirs” means that the final decision belongs to them or rests with them. This test helps you identify the possessive meaning, although it isn’t a rule for replacing words directly in every sentence.

Proofread for Unnecessary Apostrophes

Before you submit an assignment or send an important message, check your possessive forms.

Look for these common errors:

Their’s instead of theirs
Her’s instead of hers
Your’s instead of yours
Our’s instead of ours

Correcting these small mistakes can make your writing more accurate without changing your message.

FAQs:

Is Theirs or Their’s Correct?

Theirs is correct. It is the standard possessive pronoun used to show that something belongs to them. Their’s is an incorrect spelling in standard English.

Why Doesn’t Theirs Have an Apostrophe?

Possessive pronouns already express ownership, so they don’t need an apostrophe. This rule applies to mine, yours, his, hers, ours, and theirs. Apostrophes can mark possession with nouns, such as Sarah’s book, but pronouns follow their own spelling patterns.

Is Their’s Ever Grammatically Correct?

In standard English, their’s isn’t the correct form of the possessive pronoun. Use theirs in formal and informal writing when you mean “belonging to them.”

What Is the Difference Between Their and Theirs?

Their usually appears before a noun, as in “their car.” Theirs stands in for a noun phrase, as in “the car is theirs.” Both forms express possession, but they have different grammatical roles.

Is Theirs Correct in Formal Writing?

Yes. Theirs is correct in academic papers, professional documents, business emails, and everyday communication. You don’t need an apostrophe, regardless of the writing style.

Conclusion:

When choosing between theirs or their’s, the correct spelling is always theirs without an apostrophe. Theirs is a possessive pronoun that shows ownership and refers to something belonging to other people. Although their’s may look correct because many possessive words use apostrophes, it is a common spelling mistake. Remember that possessive pronouns such as theirs, yours, ours, and hers never need an apostrophe. Once you understand this simple rule, you can use theirs or their’s correctly in everyday conversations, emails, academic writing, and professional communication.