When should I use who vs. whom?

Use 'who' when it is the subject of the verb (Who called you? = He called you → use who). Use 'whom' when it is the object of a verb or preposition (Whom did you call? = You called him → use whom). The trick: if you can answer with 'he/she', use who; if you can answer with 'him/her', use whom.

Is 'To whom it may concern' correct?

Yes, 'To whom it may concern' is correct. 'Whom' follows the preposition 'to', so the object form is required. This is the standard formal opening for a letter addressed to an unknown recipient.

Who vs. Whom: What's the Difference?

Quick Answer

who = subject pronoun (like he/she) — performs the action

whom = object pronoun (like him/her) — receives the action

Explanation

WHO (subject)

The one who performs the action

Replace with: he / she

"Who called?" → He called. ✔

"The man who helped me." → He helped me. ✔

WHOM (object)

The one who receives the action / after a preposition

Replace with: him / her

"Whom did you call?" → I called him. ✔

"To whom did you speak?" → I spoke to her. ✔

The He/Him Test: Answer the question with he/him. If "he" fits → use who. If "him" fits → use whom. (Both end in "m" — whom/him!)

Always use "whom" after prepositions:

to whom, for whom, with whom, from whom, about whom, by whom

Examples

✔Who wrote this report? (subject — he/she wrote it)

✔Whom should I contact? (object — I should contact him/her)

✔She is the one who solved the problem. (subject)

✔To whom it may concern. (after preposition "to")

✘Whom called you last night?

✘Who did you invite to the party?

Common Mistakes

Incorrect: Who did the manager hire?

Correct: Whom did the manager hire? (Test: The manager hired him. → him → whom ✔)

Incorrect: The teacher whom teaches math is kind.

Correct: The teacher who teaches math is kind. (Test: She teaches math. → she → who ✔)

Practice

Choose the correct word:

"_____ is responsible for this project? And with _____ should I discuss the budget?"