Who vs whom: the easy rule, the he/him test and when you can skip whom

The rule: who is a subject, whom is an object

Merriam-Webster defines the difference like this: who refers to someone performing the action of a verb, and whom refers to someone receiving the action of a verb. In grammar terms, that makes who a subject, and whom an object.

Grammarly puts it with pronouns: who is a subject pronoun (like I, he, she, we and they), whereas whom is an object pronoun (like me, him, her, us and them). So the two words follow the same split you already know from he and him.

Both examples in the table are questions, but the same rule applies inside sentences. The manager who hired me left (who is the subject of hired). The manager whom I met left (whom is the object of met).

The he/him test, step by step

You do not need to analyse grammar to choose correctly. The Texas Bar Practice guide suggests a simple trick: temporarily substitute "he" and "him" in the place where the "who" or "whom" would go. If "he" sounds more natural, use "who", but if "him" sounds more natural, use "whom".

Try it on a question:

1. Write the question: Who/Whom should I call?
2. Answer it with a full sentence: You should call him. (not you should call he)
3. Him fits, so the word is whom: Whom should I call?

Now a different question:

1. Write the question: Who/Whom is coming to dinner?
2. Answer: He is coming to dinner. (not him is coming)
3. He fits, so the word is who: Who is coming to dinner?

A handy memory: him and whom both end in m. If you can answer with him, use whom.

For a longer sentence, find the smaller question hidden inside. In "I don't know ___ she invited", ask: she invited him. That gives whom. In "I don't know ___ is coming", ask: he is coming. That gives who.

Whom after a preposition

Whom is the usual choice right after a preposition such as to, with, for, from or about. Merriam-Webster says that whom replaces who in spots where that word would receive the action of the verb or complete the meaning of a preposition.

• To whom should I address the letter?
• She is the colleague with whom I share an office.
• He is the person for whom I bought the gift.
• Cambridge Dictionary gives this example: he told me where he went and with whom, a formal style that is preferred in some contexts to and who with.

Cambridge also shows whom after a quantity word: over 200 people attended the ceremony, many of whom had known Harry as their teacher. The phrases many of whom, some of whom and none of whom are common in careful writing and are all correct.

If you find these sentences heavy, you can rephrase them to avoid the preposition: "Who should I address the letter to?" is perfectly natural in speech, and "She is the colleague I share an office with" is easier than "with whom I share an office".

Can I just use who? When whom sounds fussy

Learners often ask whether anyone still uses whom. In writing, yes. In conversation, rarely. Cambridge Dictionary describes whom as used by people in formal styles or in writing, often with a preposition, and rarely in conversation. It is used instead of who if who is the object.

Merriam-Webster agrees that our ears are our guides. There are many constructions, like "Whom did you speak to?" versus "Who did you speak to?", in which whom may be technically correct but still feels fussy or unnatural. The same article gives "It depends on whom you ask" versus "It depends on who you ask" as another case.

In practice, use these guidelines:

• Speaking, texting and casual emails: who is almost always fine, even as an object. "Who did you invite?" sounds natural.
• Formal writing, such as a cover letter, report or exam essay: use whom where the rule requires it, especially after a preposition. "To whom it may concern" is a fixed formal opening.
• Interviews and presentations: you can say who in speech, but if you want a polished style, keep whom for fixed phrases like with whom and many of whom.

So the answer to "can I say whom I love?" is yes: The person whom I love is correct, because whom is the object of love. In everyday speech most people would say the person I love or the person who I love, and both sound fine.

Who and whom in relative clauses

A relative clause adds information about a person. The most common relative pronouns, according to Cambridge Dictionary, are who, whom, whose, which and that.

The same who/whom rule works inside the clause:

• Who as subject: The woman who lives next door is a doctor. (She lives next door.)
• Whom as object: The woman whom I met yesterday is a doctor. (I met her.)
• Whom after a preposition: The woman to whom I spoke is a doctor.

Cambridge adds that we use that instead of who, whom or which in relative clauses to refer to people, animals and things. So the following are all correct and natural: the parents we interviewed, the parents who we interviewed, the parents whom we interviewed and the parents that we interviewed. Most speakers drop the pronoun completely in the object case.

One limit to remember: we can't use that in non-defining relative clauses, the ones set off by commas. You must write My brother, who lives in Spain, called me, not My brother, that lives in Spain, called me.

Common mistakes with who and whom

Using whom as a subject (over-correcting). Some writers use whom because it sounds more formal, and then get it wrong.

• Wrong: Whom is responsible for this report?
• Right: Who is responsible for this report?

Using who after a preposition in formal writing.

• Casual (fine in speech): Who did you give it to?
• Formal (writing): To whom did you give it?

Choosing by the position in the sentence instead of the role. Do not decide by whether the word comes first. Decide by whether the person is doing or receiving the action. Whom can come first (Whom did you meet?) and who can come later in the sentence (I wonder who called).

Mixing who and whom in one sentence. Check each clause separately. The man who called me is the man whom I met last week. There are two clauses, and each has its own correct word.

A final safety net: if you cannot decide in a hurry, rewrite the sentence without either word, or use who in speech and save whom for writing where you have time to check. Natural speech has many more tricky spots than this one, and our guide on how to speak English fluently shows how to practise them without freezing.

Practice: who or whom?

Choose the correct word, then check the answers.

1. ___ is knocking at the door?
2. To ___ am I speaking?
3. The candidate ___ we interviewed was excellent.
4. I met a woman ___ works at the embassy.
5. ___ did you invite to the party?
6. She is the teacher from ___ I learned most.
7. Many of ___ had never travelled abroad.
8. I wonder ___ will win.

Answers: 1. Who (he is knocking). 2. whom (to him). 3. whom (we interviewed him), though who is acceptable in speech. 4. who (she works). 5. Whom in formal writing (you invited him), who in speech. 6. whom (after from). 7. whom (after of). 8. who (he will win).

To make this automatic, say the questions out loud using both the formal and the casual version. Read our guide to small talk in English for natural questions to practise with, because who and whom come up constantly in questions about people.