Theirs is the correct spelling. Their’s is incorrect in standard English.
People often add an apostrophe because many possessive words use one, such as John’s or children’s. However, theirs is a possessive pronoun, and possessive pronouns such as yours, ours, hers, and theirs do not take apostrophes.
In this guide, you will learn what theirs means, why their’s is wrong, how to use each form, common mistakes, and an easy way to remember the difference.
Quick Answer
Theirs is correct, while their’s is incorrect.
Use theirs when something belongs to them and you do not repeat the noun.
- This car is theirs.
- The blue seats are theirs.
Do not write their’s in standard English.
The key rule is simple: possessive pronouns do not use apostrophes.
Theirs vs Their’s: Main Difference
| Word/Phrase | Meaning | Correct? | Best Used For | Example |
| theirs | Belonging to them | Yes | Showing possession without a noun | That house is theirs. |
| their’s | Intended as a possessive form of their | No | Not used in standard English | Their’s is incorrect. |
The basic pattern
Compare these forms:
- their + noun → their house
- theirs → the house is theirs
Cambridge identifies their as a possessive determiner used with a noun and theirs as a possessive pronoun used in place of a noun.
What Does Theirs Mean?
Theirs is a possessive pronoun. It means belonging to them.
It can refer to something owned by two or more people. It can also refer to something belonging to one person when they/them is used as a singular pronoun.
Examples:
- That house is theirs.
- These books are theirs.
- The red car is theirs, not ours.
- We found the keys, but they aren’t theirs.
- The final decision was theirs.
Notice that theirs normally appears without a noun immediately after it.
- Correct: The laptop is theirs.
- Incorrect: The theirs laptop.
Oxford’s possessive-pronoun guide lists theirs alongside mine, yours, his, hers, and ours.
What Does Their’s Mean?
Their’s is not a standard English word.
It is usually a spelling mistake caused by treating their like a possessive noun that needs an apostrophe. That logic works for some forms, such as Sarah’s book, but it does not work for possessive pronouns.
For example:
- Wrong: This house is their’s.
- Correct: This house is theirs.
The apostrophe does not belong in theirs.
Why does this mistake happen?
English has many possessive forms that contain apostrophes:
- John’s car
- the dog’s bowl
- the students’ classroom
Because of these patterns, it is easy to assume that their’s should also contain an apostrophe. But theirs is already a complete possessive pronoun.
How to Use Theirs Correctly
Use their when a noun follows it:
That is their house.
Use theirs when the noun has already been mentioned or is obvious:
That house is theirs.
A useful comparison is:
| With a noun | Without repeating the noun |
| That is their car. | That car is theirs. |
| These are their books. | These books are theirs. |
| We visited their office. | The office is theirs. |
| I borrowed their seats. | The seats are theirs. |
Correct and incorrect examples
Incorrect: The blue bicycle is their’s.
Correct: The blue bicycle is theirs.
Incorrect: I think this bag is their’s.
Correct: I think this bag is theirs.
Incorrect: Those seats are their’s.
Correct: Those seats are theirs.
Where to Use Theirs
Theirs works in all normal forms of English, including school writing, professional communication, emails, conversations, and messages.
School writing
The students completed their project, and the final presentation was theirs.
Formal writing
The responsibility for the decision was theirs.
We have checked both proposals. The final choice is theirs.
Everyday conversation
Is this umbrella yours?
No, it’s theirs.
Professional communication
We supplied the equipment, but the software license is theirs.
There is no special American or British spelling difference here. Theirs is the standard form in both American and British English. Cambridge and Oxford both list it as a possessive pronoun.
Why People Get Confused
The main problem is the apostrophe.
People often learn that apostrophes can show possession:
- Maria’s phone
- the company’s office
- James’s coat
That rule is useful, but it does not apply to every possessive form.
English has a separate group of possessive pronouns:
mine, yours, his, hers, ours, theirs
These forms do not need apostrophes. Oxford specifically distinguishes possessive determiners such as their from possessive pronouns such as theirs.
There is another possible source of confusion: they’re.
- their = belonging to them
- theirs = belonging to them, used without a following noun
- they’re = they are
For example:
Their car is outside.
The car is theirs.
They’re waiting outside.
Cambridge also identifies they’re as a contraction of they are.
Common Mistakes to Avoid
Mistake 1: Adding an apostrophe
Wrong: That house is their’s.
Correct: That house is theirs.
Why: The possessive pronoun theirs has no apostrophe.
Mistake 2: Using theirs before a noun
Wrong: That is theirs car.
Correct: That is their car.
Why: Use their before a noun.
Mistake 3: Confusing theirs with they’re
Wrong: They’re house is large.
Correct: Their house is large.
Why: They’re means they are.
Mistake 4: Adding an apostrophe to other possessive pronouns
Wrong: The books are our’s.
Correct: The books are ours.
The same pattern applies to yours, hers, and theirs.
Real-Life Examples
At school
Those notebooks belong to Ali and Sara. They are theirs.
At work
We prepared the report, but the final decision is theirs.
While traveling
We thought these suitcases were ours, but they are theirs.
In a message
I found two jackets. The black one is theirs.
During a conversation
“Whose seats are these?”
“They’re theirs.”
At a restaurant
“Are these menus for our table?”
“No, I think they’re theirs.”
In a booking situation
We paid for our rooms, and the other rooms are theirs.
These examples show the main idea: theirs replaces a noun phrase that has already been identified or is understood from context.
Easy Trick to Remember
Remember this:
Their + noun, but theirs stands alone.
For example:
- Their car is new.
- The car is theirs.
And remember:
No apostrophe in theirs.
If you see their’s, remove the apostrophe.
A simple possessive-pronoun pattern
my → mine
your → yours
our → ours
their → theirs
None of these possessive pronouns needs an apostrophe.
Quick Decision Guide
Are you putting a noun immediately after the word?
↓ Yes
Use their.
their house
↓ No
Are you saying that something belongs to them?
↓ Yes
Use theirs.
The house is theirs.
↓ Never choose
their’s
It is not the standard spelling.
Mini Quiz
Choose their, theirs, they’re, or their’s.
- That red bicycle is ___.
- ___ planning to visit us tomorrow.
- The children packed ___ bags.
- This is ___ classroom.
- Those books are ___.
- Their’s is the incorrect spelling.
Answers
- theirs
- they’re
- their
- their
- theirs
- Correct statement: Their’s is incorrect; theirs is correct.
Related Confusing Words
- your or you’re
- its or it’s
- there or their
- they’re or their
- ours or our’s
- yours or your’s
- who’s or whose
- who’s or whose
FAQs About Theirs or Their’s
Is theirs correct?
Yes. Theirs is the correct standard spelling for the possessive pronoun meaning “belonging to them.”
Is their’s correct?
No. Their’s is not the standard English spelling. Write theirs instead.
What is the difference between their and theirs?
Their comes before a noun: “their house.” Theirs replaces the noun: “The house is theirs.”
Why doesn’t theirs have an apostrophe?
Theirs is a possessive pronoun. Possessive pronouns such as ours, yours, hers, and theirs are written without apostrophes.
Is theirs formal or informal?
Theirs is standard English and is suitable for formal and informal situations, including academic writing, business communication, and everyday speech.
References
- Oxford Learner’s Dictionaries Possessive Pronouns
- Cambridge Dictionary “theirs”
- Cambridge Dictionary “their”
- Cambridge Dictionary “they’re”
Conclusion
Theirs is correct, and their’s is incorrect in standard English. Use their before a noun and theirs when the noun does not need to be repeated. Neither form requires an apostrophe. The easiest rule is: their house, but the house is theirs.
Ava Collins