Whose vs Who's: Possession vs Contraction

The Apostrophe Makes All the Difference

Quick Answer

Whose = possession (belonging to whom). Who's = who is / who has.

Test: Can you expand it to "who is" or "who has"? If yes, use who's. If no, use whose.

When to Use "Whose" (Possession)

Whose shows ownership/possession—like his, hers, its.

  • Whose book is this? → belongs to whom ✓
  • I know whose fault it was. → belonging to whom ✓
  • The girl whose car broke down. → her car ✓
  • Whose idea was this? → belonging to whom ✓
  • The house whose roof leaked. → its roof ✓

When to Use "Who's" (Contraction)

Who's is a contraction of "who is" or "who has."

  • Who's coming to the party? → who is coming ✓
  • Who's been eating my food? → who has been ✓
  • Who's there? → who is there ✓
  • I wonder who's at the door. → who is ✓
  • Who's got the keys? → who has ✓

Comparison Chart

Word Definition Test Example
Whose Possession Can't expand to "who is" "Whose pen is this?"
Who's Who is / Who has Expand: "who is..." "Who's calling?" (Who is)

Common Mistakes & How to Avoid Them

❌ Incorrect:

"Who's book is this?"

✓ Correct:

"Whose book is this?"

Why? "Who is book" doesn't make sense. It's possession—use "whose."
❌ Incorrect:

"Whose coming to dinner?"

✓ Correct:

"Who's coming to dinner?"

Why? "Who is coming"—use the contraction "who's."
❌ Incorrect:

"The person who's car that is."

✓ Correct:

"The person whose car that is."

Why? The car belongs to someone—use "whose."

Quick Tips

💡 The Expansion Test

Try expanding to "who is" or "who has." If it works, use who's. If not, use whose.

✅ Like It's vs Its

Same pattern! It's = it is. Its = possession. Who's = who is. Whose = possession.

Frequently Asked Questions

Can "whose" refer to things (not just people)?

Yes! "The book whose cover is torn." While "of which" is sometimes preferred for things, "whose" is widely accepted.

Is "who's" always informal?

Contractions are more casual, but "who's" is perfectly acceptable in most writing. Avoid contractions only in very formal documents.

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