When to Use Who or Whom

Many writers struggle with when to use the words who or whom. When in doubt, they will use that instead. But that and who are not interchangeable either.

How do you know which word to use? 

When to Use Who

Who is used to refer to the subject of a sentence. A subject is a person, place, or thing doing an action or being described.

Examples

Who wrote the manuscript?

Who performed the experiments?

When to Use Whom

Whom is used to refer to the object of a verb or preposition. Prepositions are words that link nouns, pronouns, and phrases to other words in a sentence (e.g., to, for, of, with).

Examples

Whom did she invite?

I do not know with whom I will collaborate.

The Difference Between Who and Whom

How do you know when to use who or whom? Use who if you can replace the word with he, she, or they. And use whom if you can replace the word with him, her, or them.

When testing word to use, you may need to temporarily rearrange the sentence a bit. Let’s look at a few examples.

Example 1

Who/whom cultured the cells?

In this example, try substituting she and her in a rearranged version of the sentence.  

She cultured the cells.

Her cultured the cells.

Here, she works, but her doesn’t. In this case, you want to use who.

            Who cultured the cells?           

Example 2

From who/whom should I order the media?

Try substituting they and them in a modified version of the sentence.

I should order from they.

I should order from them.

Here, they doesn’t work, but them does. In this example, you want to use whom.

From whom should I order the media?

Example 3

She is a renowned researcher, who/whom is also an excellent teacher.

Try substituting she and her where you see who/whom.

She is a renowned researcher. She is also an excellent teacher.

She is a renowned researcher. Her is also an excellent teacher.

Here, she works, so you want to use the word who.

She is a renowned researcher, who is also an excellent teacher.

If you do not feel confident about which word to use, you can reword the sentence instead.

She is a renowned researcher and an excellent teacher.

This version is also shorter and clearer, which improves the overall readability.

How do you know when to use who or whom?

Use who if you can replace the word with he, she, or they. Use whom if you can replace it with him, her, or them.