Both show that something belongs to a group of people. The difference is where they go in the sentence.
- Their comes before a noun: their bag, their dog.
- Theirs stands alone, with no noun after it: The bag is theirs.
Their: before a noun
Use their when a noun comes straight after it.
Where is their house?
The twins love their new bikes.
Their team won the match.
I borrowed their map.
Their can't stand alone. You can't say The map is their.
Theirs: stands alone
Use theirs when the noun has already been mentioned, or is easy to guess. It replaces their plus the noun.
That house is theirs.
Our bikes are red, and theirs are blue.
I found my shoes, but not theirs.
Is this map yours or theirs?
Theirs means their house, their bikes, their shoes or their map, without saying the noun again.
Easy way to tell them apart
Look at what comes right after the word:
- A noun comes after it? Use their. Their dog barks.
- Nothing comes after it, or just a verb? Use theirs. The dog is theirs.
💡 The OddLingo Trick
Their needs a noun. Theirs stands alone.
Say their and wait for the thing: their ... dog. Say theirs and the thing is already inside the word.
⚠️ Common mistakes
No noun after it? Use theirs.
❌ The red car is their.
✅ The red car is theirs.
A noun after it? Use their.
❌ Theirs dog is very fluffy.
✅ Their dog is very fluffy.
No apostrophe in theirs.
❌ The blue bike is their's.
✅ The blue bike is theirs.
Good to know
People add an apostrophe because 's shows ownership on most words, like Mia's bag. But theirs is already a possessive pronoun, so it never needs one. The same is true of hers, ours and yours.
If you want the full story with there and they're, see their vs there vs they're. For apostrophes that do mean "something is missing", try your vs you're.
💬 In a conversation
Sam: Is this your umbrella?
Mia: No, mine is blue.
Sam: Maybe it's theirs.
Mia: Whose?
Sam: The twins. Their umbrella is purple.
Mia: Then it's theirs, and I'm still wet.