Who is used as a subject pronoun in questions and clauses, while whom is used as an object pronoun. Who refers to the person performing the action; whom refers to the person receiving it.
Understanding the distinction between who and whom begins with recognizing their grammatical roles. Who functions as the subject-the doer of the verb. Whom functions as the object-the receiver of the verb's action. This difference mirrors other pronoun pairs like he/him or they/them, but who/whom is often misused because the distinction isn't always obvious in spoken English.
For example, in "Who wrote this letter?" who is the subject-it performs the action of writing. In "To whom did you send the package?" whom is the object-it receives the action of being sent to. The preposition "to" makes the object role clearer, which helps identify whom as correct.
Who acts as the subject in both direct and indirect questions. When asking about the performer of an action, use who. For instance: "Who is leading the team?" Here, "who" is the subject of "is leading."
Whom is used when the pronoun is the object of a verb or preposition. Consider: "Whom did you invite to the meeting?" The verb "invite" takes an object-the person being invited. Since "whom" is the object, it is correct. If you replace "whom" with "him," the sentence becomes "Whom did you invite?" → "Him did you invite?" - which sounds awkward but confirms the object role.
When a preposition appears before the pronoun, whom is almost always required. Prepositions such as to, for, with, and about take objects. So: "With whom are you going?" is correct. "With who are you going?" is incorrect in formal grammar. The preposition "with" requires an object, so "whom" is needed.
A frequent error is using who after a preposition. People say "Who did you give the book to?" instead of "Whom did you give the book to?" Even though "Who did you give the book to?" is common in speech, it is not standard in formal writing. The rule remains: prepositions take objects, so whom is correct.
Another mistake is confusing the structure of relative clauses. In "The person who helped me was kind," who is the subject of "helped." But in "The person whom I saw at the store was wearing a red coat," whom is the object of "saw." The verb "saw" requires an object, so "whom" is correct.
Here's a non-obvious correction: many people assume that whom is outdated or overly formal. But it is still correct and necessary in formal and academic writing. According to the Grammarly Blog, whom remains valid in proper English, especially in written contexts. Using who in place of whom in formal writing can reduce clarity and credibility.
To decide between who and whom, try replacing the pronoun with he/him or she/her. If the sentence sounds correct with "he" or "she," use who. If it sounds correct with "him" or "her," use whom.
Test 1: "___ is responsible for the project?" Replace with "He is responsible..." → correct. Answer: who.
Test 2: "I asked ___ to review the report." Replace with "I asked him to review..." → correct. Answer: whom.
This test works because "he" is a subject pronoun, "him" is an object pronoun. The substitution reveals the grammatical role.
| Usage | Correct Pronoun | Why |
|---|---|---|
| "___ called you?" | who | Subject of "called" |
| "To ___ did you speak?" | whom | Object of preposition "to" |
| "She is the woman ___ saved the child." | who | Subject of "saved" |
| "The man ___ we met yesterday is my uncle." | whom | Object of "met" |
I once edited a college application essay where the student wrote: "I spoke to the professor who taught me." That sentence is correct-"who" is the subject of "taught." But later, they wrote: "I asked the professor who gave me feedback." Here, "who" is actually the subject of "gave," so it's correct. However, if the sentence had been "I asked the professor whom I gave feedback to," then "whom" would be needed after the preposition "to."
The difference between who and whom is not about formality versus casualness. It's about grammatical function. While "who" dominates in everyday speech, "whom" persists in formal writing, legal documents, and academic texts. The Merriam-Webster Dictionary defines "whom" as "used as the object of a verb or preposition," confirming its ongoing relevance.
Also, whom is not interchangeable with who simply because it sounds old-fashioned. Misusing whom as who in formal writing weakens precision. For example, "Whom did you see?" is correct. "Who did you see?" is acceptable in informal settings but less precise in formal contexts.
When in doubt, substitute "he" or "she" for who, and "him" or "her" for whom. If the sentence sounds natural with "he" or "she," use who. If it sounds natural with "him" or "her," use whom.
Try this: "___ is the winner?" → "He is the winner." → Use "who." "Give the award to ___?" → "Give the award to him." → Use "whom."