Who and whom cause genuine uncertainty for many writers. The word whom in particular has an air of formality that makes some writers avoid it altogether — and an air of pretension that makes others use it incorrectly in an attempt to sound more formal. In fact, the distinction between who and whom follows a clear and learnable grammatical rule.
Once you understand it, you will be able to apply it correctly every time. This guide explains the rule simply, gives you a reliable test you can use on any sentence, and provides clear examples across formal and academic writing contexts.
The Quick Answer
Use who when the word refers to the subject of a verb — the person performing the action.
Use whom when the word refers to the object of a verb or preposition — the person receiving the action or following a preposition like to, for, by, with, from.
Subject vs Object — The Grammatical Basis
The who/whom distinction is the same as the he/him or she/her distinction — it is a matter of grammatical case. In English:
Who is the subject form — like he, she, they
Whom is the object form — like him, her, them
Just as you would say He submitted the report (subject) but The report was submitted by him (object), you use who when it is doing something and whom when something is being done to it or it follows a preposition.
The He/Him Test
The most reliable way to decide between who and whom is the he/him substitution test. Replace who or whom in your sentence with he or him:
If he fits → use who
If him fits → use whom
This works because both who and he are subject forms, and both whom and him are object forms. If you need to rearrange the sentence slightly to make the substitution work, do so — the key is identifying whether he or him is the natural fit.
___ submitted the report first? → He submitted the report first. → Use who: Who submitted the report first?
To ___ should I address the letter? → I should address the letter to him. → Use whom: To whom should I address the letter?
Examples in Context
Who — Subject Form
The student who submitted first received her feedback earliest.
Who is responsible for proofreading the final draft?
The editor who reviewed the manuscript made several useful suggestions.
She is the researcher who published the original study.
Whom — Object Form
The student to whom the feedback was addressed responded promptly.
The editor, with whom I have worked for several years, reviewed the manuscript.
To whom it may concern:
She is the researcher whom the committee selected for the award.
Who vs Whom in Questions
In questions, use the he/him test by answering the question and seeing which fits:
Who/Whom called the meeting? → He called the meeting. → Who called the meeting.
Who/Whom did you speak to? → I spoke to him. → Whom did you speak to? (or: To whom did you speak?)
Who/Whom should we contact? → We should contact him. → Whom should we contact?
Who vs Whom in Relative Clauses
In relative clauses, the same rule applies. Focus on the role within the clause itself, not the whole sentence:
The supervisor who reviewed the thesis suggested significant revisions. (who = subject of reviewed)
The supervisor whom I contacted responded within 24 hours. (whom = object of contacted — I contacted him)
The candidate who performed best in the interview was offered the position. (who = subject of performed)
The candidate whom we interviewed last week has accepted the offer. (whom = object of interviewed — we interviewed her)
Formal vs Informal Usage
In informal speech and writing, who is widely used in both subject and object positions — and this is generally accepted. “Who did you speak to?” sounds natural in conversation even though “Whom did you speak to?” is grammatically correct.
In formal writing — academic papers, professional reports, legal documents, formal correspondence — the who/whom distinction should be observed. Using whom correctly in these contexts signals grammatical precision and attention to detail. Using whom incorrectly (when who is actually correct) can sound worse than using who throughout, so when in doubt in a formal context, apply the he/him test to be certain.
Frequently Asked Questions
Is it who or whom in “to who it may concern”?
The correct formal phrase is To Whom It May Concern — with whom, because the pronoun follows the preposition to and is therefore in the object form. This is one of the most commonly used formal phrases in professional correspondence, and using who here would be considered a grammatical error in formal writing.
Is it who or whom after a preposition?
After a preposition (to, for, by, with, from, about etc.), always use whom. Prepositions take the object form: to whom, for whom, by whom, with whom, from whom. This is one of the clearest rules governing whom usage.
Is whom becoming outdated?
In informal speech and writing, whom is used less frequently than it once was, and its absence is rarely noticed in casual contexts. However, in formal academic and professional writing, whom remains the correct and expected form in object positions. Using it correctly in formal contexts signals grammatical competence; avoiding it entirely in formal writing can appear evasive.
Can I just use who for everything?
In informal writing and speech, yes — and you will rarely be corrected. In formal academic and professional writing, using who where whom is grammatically required is a noticeable error. For formal documents, taking the time to apply the he/him test is worth the effort.
Summary
Use who for the subject — the person performing the action
Use whom for the object — the person receiving the action, or following a preposition
Quick test: substitute he or him — if he fits, use who; if him fits, use whom
Always use whom after prepositions: to whom, for whom, by whom
In formal writing, applying the distinction correctly signals grammatical precision
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