Theirs vs Their’s

What’s the difference between theirs and their’s?


Theirs is the third person plural possessive pronoun – it replaces their + noun.

Is this yours or theirs?

He found a book – is it theirs?

I can’t find my keys, but theirs are on the table.

Theirs is a better idea.

Theirs is over here.


Though you may see their’s written even by native speakers, it is incorrect. Theirs should never have an apostrophe.

The Bottom Line

The idea that theirs needs an apostrophe comes out of the fact that on virtually every other word, ‘s indicates possession, so English speakers sometimes think theirs should be spelled their’s. However, this is always incorrect – theirs is the only correct spelling.

Related difficulties:

3 comments for “Theirs vs Their’s

  1. Shelly Kegan
    26 April 2014 at 14:59

    This is not exactly true, the current spelling of theirs comes from middle english their’s.

  2. Mark
    26 February 2015 at 09:34

    The comment still doesn’t answer WHY? If all other possessive words use an apostrophe then why is it wrong or incorrect to do add it on this single word? What is the rule? What is the reason?

    • lkl
      28 February 2015 at 07:12

      I can’t answer that. Sometimes grammar just is. Why do we say “I walk, you walk, we walk, they walk” but “he walks”? That’s just the way the grammar evolved. In the case of possessives, “their’s” simply is not a word. It’s wrong.

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