Blog Grammar Rules Which vs. That: When to Use Each

Which vs. That: When to Use Each

Millie Dinsdale

Millie Dinsdale

Content Manager at ProWritingAid

Published Apr 02, 2022

Which vs that title

Many people use “which” and “that” interchangeably but the two words are not synonymous.

“Which” and “that” both refer to something previously mentioned when introducing another clause.

The difference between them is “which” introduces a non-essential clause and “that” introduces an essential one.

Read on to learn how to identify clauses and subsequently use the right word every single time.

Contents:
  1. The Trick for Remembering Which vs. That
  2. Which vs. That: Let Us Explain
  3. Examples of When to Use Which vs. That
  4. Which vs. That: Quiz

The Trick for Remembering Which vs. That

There’s a simple trick to remember the difference:

If your sentence has a clause but does not need it, use “which”; if the sentence does need the clause, use “that.”

Before we look at when to use “that” or “which,” let’s quickly discuss what a clause is.

What Is a Clause?

A clause is a group of words that contains a subject and a predicate.

A subject is the thing that the clause is about. A predicate contains the verb and says something about the subject.

Examples of clauses are:

  • When I was running (dependent)
  • That went missing yesterday (dependent/adjective)
  • I ate pasta and apple crumble (independent)

There are two main types of clauses: independent and dependent.

Dependent clauses can be split further into noun and adjective clauses.

Within these categories, there are two types of noun clauses, restrictive and non-restrictive, which are essential to understand the difference between “which” and “that.”

Different types of clauses

Which vs. That: Let Us Explain

The clause that comes after the word “which” or “that” is the determining factor in deciding which one to use.

If the clause is essential to the meaning of the sentence, you use “that.”

If you could drop the clause and leave the meaning of the sentence intact, use “which.”

For example:

  • The school that burned down last week is still smoking.
  • The school, which I attended as a child, burned down last week.

In the first sentence, the clause “that burned down last week” is essential because it identifies the school that is still smoking. Without the clause, we could refer to any school. With an essential clause, use the word “that.”

In the second sentence, the clause “which I attended as a child” is non-essential because it is unnecessary to identify the school that burned down. Without it, the sentence would still make sense. With a non-essential clause, use the word “which.”

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How to Use Commas with Which vs. That

“Which” and “that” are relative pronouns that begin adjective clauses. Both tell us a little more about the noun they follow.

The clauses that start with “that” are called restrictive because they ONLY tell us about the noun being discussed and are not surrounded by commas.

The “which” clause is non-essential or non-restrictive and‌ is always set off from the rest of the sentence with commas.

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Examples of When to Use Which vs. That

  • The old schoolhouse, which is one of my favorite historical sites to visit, is in dire need of renovation.

In this case, you could drop the clause “which is one of my favorite historical sites to visit” and the sentence would still make sense.

On the flip side, try this example:

  • The type of antibiotic that the doctor prescribed made me nauseous.

Clearly, it’s not just any antibiotic, but the one the doctor prescribed that made you sick to your stomach. The sentence without the clause doesn’t make sense.


Start Editing Like a Pro

Once you’ve checked your use of “which” and “that,” use ProWritingAid to make sure the rest of your sentence is stylistically and grammatically correct, too.

prowritingaid correction for no comma before which

Our Realtime report lets you see and fix grammar, style, and spelling issues quickly. If you would like to know more about a suggestion, just click on the orange “i.”

You’ll see articles and videos to help you learn as you edit.


Extended Example of Which vs. That

In some sentences, both “which” and “that” are grammatically correct but provide slightly different meanings, like in the example below.

  • Our home, which has four bedrooms, is located in the Caribbean.
  • Our home that has four bedrooms is located in the Caribbean.

The first sentence discusses the location of your only home and it just so happens to have four bedrooms. Lucky you, it’s in the Caribbean.

The second sentence points out that the home you own with four bedrooms is located in the Caribbean, which means you have more than one home. “That has four bedrooms” is how you distinguish between your many homes.

Which vs. That: Quiz

Now that you know how to use “which” and “that,” are you ready for a quick test? I have omitted all commas because otherwise it would be too easy.

1) The lion __ I saw at the zoo scared me.

2) My summer chemistry project __ I handed in yesterday got an A!

3) My dress __ I wore last week has a hole in it.

4) My boat __ is at the summer house in Devon was repainted last week.

5) Jupiter __ is next to Saturn is the largest planet in our solar system.

Answers: 1) either 2) which 3) that 4) either 5) which

A big congratulations if you got all of them right because I was a little mean with sentences 1 and 4. Both the words “that” and “which” are grammatically correct depending on whether you have seen lions in the wild and how many boats the speaker has.

In sentence 4, if they have multiple boats then “that” is correct because it is necessary to identify which boat they are discussing. If they only have one boat then “which” is correct because we would already know where the boat is located and therefore the clause is not essential.

As a writer (me) once said:

“That which confuses you can only make you a better writer.”

Do you have any sentences like this that use both “which” and “that”? Share them in the comments.


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Millie Dinsdale

Millie Dinsdale

Content Manager at ProWritingAid

Millie is ProWritingAid's Content Manager. A recent English Literature graduate, she loves all things books and writing. When she isn't working, Millie enjoys gardening, re-reading books by Agatha Christie, and running.

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You may want to reconsider using the word "nauseous" with the more appropriate word, "nauseated."
OK, I've been familiar with the distinction between essential and additional relative clauses for a long time. And I've seen many published examples of "which" being used in both situations. To summarise this article:: Use " which" to introduce additional (non-essential) information. Use " that" to introduces essential information fine-tuning the description. When PWA sees "which" without a preceding comma, it merely suggests you might want to add one. It never suggests simply changing "which" to "that". It would help enormously if your software reflected the hints you publish in these blogs.
Thanks for this! We work hard to have our software do just that, but at the end of the day, it is just software. We are always working to improve it! :)
Isn’t it “farther from the truth?”
There is a grammar error in the article: "The 'which' clause is non-essential or non-restrictive, and as such, is always set off from the rest of the sentence with commas." This sentence contains a misplaced comma, which separates the subject from one of the verbs of its compound predicate — the second "is." Here are possible corrections: "The 'which' clause is non-essential or non-restrictive[ and] is always set off from the rest of the sentence with commas." "The 'which' clause is non-essential or non-restrictive[ and,] as such, is always set off from the rest of the sentence with commas." "The 'which' clause is non-essential or non-restrictive, and as such,[ it] is always set off from the rest of the sentence with commas."
Thanks for sharing your thoughts! We appreciate the feedback. :)
The explanation on the 'towered building' example confused me a little. Unlike the others it sort of claims that the use of "that" creates a "causal" connection between the description it introduces and the rest of the sentence, while the emphasis is clearly on the circumstantial connection. I mean, of course, there's probably a good reason to choose one distinguishing feature over another, but the reason "The building-gave me the shivers" isn't necessrily the fact that it "towered over the sightseers". I was reading this example back and forth, and couldnwt get to a conclusion- Doesn't "that" suppose to distinguish objects from similar ones that don't share its differentiating feature? On the other hand, does the use of "that" obligate the existence of similar objects? This arcticle is very helpful, maybe the one that supplies the most comprehensive view on this subject( as far as I've been able to find ), hence simply great. I would really appreciate any sort of feedback, answer, clarification etc.
You've come to the right place! This is the kind of thing we absolutely love to nerd-out about. I've brought your query to the attention of our content lead. Sounds like we may need a "which or that" forum sometime soon! :)
Well, it looks like you aren't too interested in correcting the error on this page I identified for you on March 16. Perhaps if you knew about more errors on this page, you could be roused to action. "In this case, you could drop the clause 'which is one of my favorite historical sites to visit' and the sentence still makes sense:" These two independent clauses are not short and are joined by a coordinating conjunction. This requires a comma to avoid a run-on sentence. "In this case, you could drop the clause 'which is one of my favorite historical sites to visit[,' ]and the sentence still makes sense:" "In the second one, however, the fact that the building was towering over the sightseers gave me the shivers[ ]because I thought it was going to fall over on them. — a comma was erroneously introducing a dependent clause. "The first sentence discusses the location of your only home[, ]and it just so happens to have 4 bedrooms. — another run-on sentence. I hope you find the time to correct these.
Thanks again for letting us know! I'll alert our team again.
Is the sentence "the two organizations to which he reported" correct, or "the two organizations that he reported to"? Thanks
I believe that the second option, "the two organizations that he reported to" is the correct answer. However, I am not 100% sure and would really appreciate the thoughts of other people here in the comments?
I learnt a lot in this post!
We're happy to hear that. Thanks for letting us know!
It is the blue car that/which caused the accident. That/which I couldn't figure out
Hey there! The correct answer for that sentence would be "that." The explanation being: "That introduces an essential clause and which introduces a nonessential clause. This clause is essential because without it, we could be referring to any blue car in the world." I hope this helps!

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