Quick answer: Who is a subject pronoun (like he, she, they). Whom is an object pronoun (like him, her, them). Quick test: answer the question with he or him — if “he” fits, use who; if “him” fits, use whom. For a fuller definition, see the Cambridge Dictionary entry for ‘who’.
Comparison Table
| Word | Type | Function | Example | Substitution test |
|---|---|---|---|---|
| who | subject pronoun | performs the action | Who called? | “He called” → use who |
| whom | object pronoun | receives the action | Whom did you call? | “I called him” → use whom |
Using Who
Who replaces the subject of a verb — the person doing the action. Think of it the same way you use he, she, or they.
Who is responsible for this? (= He is responsible.)
The person who wrote this is brilliant. (= She wrote this.)
Who called the meeting? (= They called the meeting.)
Who in Relative Clauses
In a relative clause, use who when the pronoun is the subject of that clause — when it performs the verb that follows it.
The manager who approved the budget resigned.
Anyone who wants to join is welcome.
Using Whom
Whom replaces the object of a verb or the object of a preposition — the person receiving the action. Think of it the same way you use him, her, or them.
Whom did you invite? (= You invited him.)
The person to whom this was sent has left. (= This was sent to her.)
To whom should I address the complaint? (preposition to → object → use whom)
Whom After Prepositions
After any preposition (to, for, with, by, from, about), you must use whom, not who. This is one of the clearest rules in formal English.
To whom it may concern,
With whom did she travel?
The colleague for whom I covered was grateful.
To who it may concern, ✗ (informal error)
The He / Him Substitution Trick
This one-step test works almost every time. Rephrase the sentence as a statement and try replacing the blank with he or him:
- If he sounds right → use who (both end in a vowel sound)
- If him sounds right → use whom (both end in m)
Example: “___ wrote the report?”
→ “He wrote the report.” ✓ → Use who: Who wrote the report?
Example: “___ did you consult?”
→ “I consulted him.” ✓ → Use whom: Whom did you consult?
Common Mistakes
✗ To who should I send this?
✓ To whom should I send this?
After any preposition, use whom in formal English.
✗ Whom is in charge here?
✓ Who is in charge here?
Test: “He is in charge” → he fits → use who.
✗ The student whom passed the test celebrated.
✓ The student who passed the test celebrated.
Here “who” is the subject of “passed” — substitute “he passed” to confirm.
In casual speech, many native speakers use who everywhere. “Who did you speak to?” is widely accepted informally. However, for formal writing, academic essays, and English exams, using whom correctly is expected at B2–C1 level and above.
Also confusing: Accept vs Receive, Advise vs Advice, Borrow vs Lend. Browse all confusing word pairs →
Quick Check: Who or Whom?
Four fill-in-the-blank questions — reveal the answer for each one.
1. “___ is in charge of the project?” (Who / Whom)
2. “To ___ should I address the complaint?” (who / whom)
3. “___ did you speak to at reception?” (Who / Whom)
4. “The candidate ___ we selected starts Monday.” (who / whom)
Who or Whom?
Three questions — choose the correct word for each sentence.
1. “___ called?” (subject pronoun, “he” fits)
2. “___ did you call?” (object pronoun, “him” fits)
3. Which word functions like “him” or “her”?
Frequently Asked Questions
What is the difference between who and whom?
Who is a subject pronoun (like he, she, they) and is used when the pronoun is performing the action. Whom is an object pronoun (like him, her, them) and is used when the pronoun receives the action. Quick test: if you can answer the question with “he”, use who; if you can answer with “him”, use whom.
How do I know when to use who or whom?
Replace who/whom in the answer with he or him. If “he” sounds right, use who. If “him” sounds right, use whom. Example: “Who called?” → “He called” (he fits, so use who). “Whom did you call?” → “I called him” (him fits, so use whom).
Is “whom” still used in modern English?
Yes, whom is still used, especially in formal writing, legal texts, and careful speech. In informal conversation, many speakers replace whom with who, but in formal contexts — and in IELTS, TOEFL, or professional writing — using whom correctly demonstrates a high level of accuracy.
Can I always use “who” instead of “whom”?
In informal speech, many people say who where formal grammar requires whom, and it is usually understood. However, in formal writing, academic essays, or professional communication, using whom in the object position is expected and marks you as a proficient user of English.
What is a simple trick to choose between who and whom?
Use the he/him substitution trick: rephrase the sentence and see which fits. If “he” (or she/they) works, choose who. If “him” (or her/them) works, choose whom. Memory aid: he and who both end in a vowel sound; him and whom both end in m.
Is “to whom” correct English?
Yes. After a preposition (to, for, with, by, from), you must use whom, not who. Examples: “To whom should I address the letter?”, “For whom was this written?”, “With whom did she travel?”. Using “who” after a preposition is a common error in formal writing.
What is the difference between “who” and “that” as relative pronouns?
Who (and whom) refer to people. That can refer to people or things, but in formal writing who is preferred for people. Example: “The teacher who helped me” (preferred in formal English) vs “The teacher that helped me” (acceptable but less formal).
How do who and whom appear in relative clauses?
In a relative clause, who is the subject of the clause: “The person who wrote this is brilliant.” Whom is the object: “The person whom we hired starts Monday.” You can test it by replacing the relative pronoun with he/him in the clause alone.
What is “whoever” and “whomever”?
Whoever is the subject form (like who): “Whoever did this should apologise.” Whomever is the object form (like whom): “You may invite whomever you wish.” The same he/him substitution test applies within the clause that follows.
How does knowing who vs whom help in IELTS or Cambridge exams?
In IELTS and Cambridge exams (B2 First, C1 Advanced), correct use of whom in relative clauses and after prepositions demonstrates grammatical range and accuracy, which are key marking criteria. Examiners expect C1/C2 learners to use whom appropriately in formal writing tasks.