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Want to know what one of my biggest pet peeves as a proofreader is? That vs. which! I can’t read anything without seeing which being used incorrectly!
So why do people get them mixed up so often? How do you know when to use which instead of that?
I cover the rules below and provide examples so you can see how to use them properly. To test your knowledge, stick around for the quiz at the end of this article!
(Please note that I used the Chicago Manual of Style (CMOS) as my reference guide unless otherwise noted.)
Table of Contents
What Is the Rule for Using That vs. Which?
In very simple terms, use that to introduce a restrictive clause and use which to introduce a nonrestrictive clause.
What Is the Difference between Which vs. That?
That and which both serve a similar purpose, but using them incorrectly can change the meaning of a sentence.
Deciding whether to use that vs. which depends on whether the clause is restrictive or nonrestrictive.
Use That with Restrictive Clauses
A restrictive clause contains information that is necessary to understand the preceding noun. Restrictive clauses (also known as essential clauses or defining clauses) are NOT usually set off by commas.
If omitting the clause would change the meaning of the sentence, then you should use that.
Example:
The store that sells Irish food was overrun with customers on St. Patrick’s Day.
The clause “that sells Irish food” is essential to the meaning of this sentence. It tells us which store was overrun with customers.
More Examples of Using That with a Restrictive Clause:
He stole the car that was parked outside the church.
The contract that she signed forbade her from stealing their clients.
Cars that don’t have seatbelts are illegal.
Use Which with Nonrestrictive Clauses
A nonrestrictive clause contains supplementary information that is not necessary for understanding the noun. A comma (or pair of commas) should separate the nonrestrictive clause from the rest of the sentence. Nonrestrictive clauses are also known as nonessential clauses or nondefining clauses.
If you can remove the clause without changing the meaning of the sentence, then which is probably correct. The clause is simply providing extra information.
Example:
Her dress, which she got in a thrift store for $10, fits her like a glove.
In the example above, the fact that she got the dress for a steal is supplementary information. You could remove it and not obscure the meaning of the sentence, which is that the dress fits her like a glove.
If the sentence were “Her dress that she got at a thrift store for $10 fits her like a glove,” you could not remove the restrictive clause “that she got at a thrift store for $10” from the sentence as then we wouldn’t know which dress fits her like a glove.
More Examples of Using Which with a Nonrestrictive Clause:
They passed their exams, which was a huge relief.
He always leaves the toilet seat up, which is why she wants to divorce him.
She said she was moving to Hawaii next week, which was news to him.
British English vs. American English
In British English, which and that can be used interchangeably in restrictive clauses. However, according to the Oxford Style Manual, only which may be used in nonrestrictive clauses.
In American English, that is used in restrictive clauses, and which is used in nonrestrictive clauses. Which can be used restrictively if it is preceded by a preposition.
Example: As a proofreader, I often edit documents in which people use that vs. which incorrectly.
Grammar Posts
Different From vs. Different Than
Who vs. Which vs. That?
Let’s add another layer of complexity. Where does who fit in?
Who describes people.
That describes objects or groups.
Which describes objects.
Who is a relative pronoun that describes individual people or groups of people. It can be used to introduce restrictive and nonrestrictive clauses.
Examples:
Nonrestrictive: Our next-door neighbors, who won the lottery, have three children.
Restrictive: Our neighbors who won the lottery live next door.
In the first example, the fact that our next-door neighbors won the lottery is just extra information and could be removed from the sentence. The real point of the sentence is that they have three children. In the second example, who won the lottery is integral to the sentence because we particularly want to know where the people who won the lottery live.
That and which are also relative pronouns. They are generally not used when talking about people. CMOS does specify that it is acceptable to use that in reference to people, but who is more commonly used.
What about animals? Are they a that or a who? CMOS says that “who normally refers to a human being”; however, the AP Stylebook says that “who is the pronoun used for references to human beings and to animals with a name.”
Who vs. Which vs. That Quiz
Choose the correct word in each sentence. You can find the answers at the bottom of this blog post.
- The coat, that/which/who had hung on the coat stand for years, didn’t belong to any of them.
- Paul is on the football team that/which/who had to concede due to not having enough players.
- We have a friend that/which/who separates her M&Ms into colors before eating them.
- The dog that/which/who has no tail bit the boy.
- He said he played football in high school, that/which/who is just not true.
Final Thoughts on That vs. Which
I hope you have a better understanding of when you should use that vs. which now. All you need to do is figure out if the clause is restrictive or nonrestrictive.
If you want to dive deeper into tricky grammar issues, check out the resources below.
Need More Grammar and Punctuation Help?
Grammar can be tricky. We’re bombarded with bad grammar on social media every single day, so it’s not surprising that we’re sometimes not sure what’s right and what’s wrong!
If you’d like to improve your grammar and punctuation skills so you can communicate better or hone your proofreading skills, Grammar Lion: A Grammar Refresher is an in-depth but easy-to-understand course.
Commas tripping you up? Take this free comma course to refresh your knowledge.
Check out my review of Grammar Lion here.
Further Reading
Related Content: 15 Essential Reference Books for New Proofreaders
Who vs. That vs. Which Quiz Answers
- The coat, which had hung on the coat stand for years, didn’t belong to any of them.
- Paul is on the football team that had to concede due to not having enough players.
- We have a friend who separates her M&Ms into colors before eating them.
- The dog that has no tail bit the boy.
- He said he played football in high school, which is just not true.
Punctuation Posts
How to Use an Ellipsis: Chicago vs. AP Style
En Dash vs. Em Dash: When and How to Use Them
How to Use an Apostrophe (and Mistakes You Need to Avoid)
How to Use Commas (and Mistakes to Avoid)
Colon vs. Semicolon: When and How to Use Them
How to Use Quotation Marks (and the Difference between Single Quotes vs. Double Quotes)
