BlogGrammar RulesShould I Use "Which" or "That"?

Should I Use "Which" or "That"?

The ProWritingAid Team
ProWritingAid: A grammar guru, style editor, and writing mentor in one package.
Published Nov 13, 2020

When to use That and Which

Do you use "which" and "that" as interchangeable words in sentences because they mean the same?

That couldn't be further from the truth. We're here to help you determine when to use each word.

  1. The Quick & Dirty Trick
  2. Which or That: Let Us Explain
  3. Some Examples
  4. Extended Examples
  5. Conclusion
  6. Try ProWritingAid's Editor For Yourself

The Quick & Dirty Trick

Of course, there's a trick:

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

That's simple, right?

Which or 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 absolutely pertinent 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."

To drop some technical terms, “which” and “that” are relative pronouns that begin adjective clauses, which are clauses that tell us a little more about the noun they follow. The clauses that start with “that” are called restrictive because they tell us ONLY about the noun being discussed.

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

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Some Examples

  • 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 still makes sense:

  • The old schoolhouse is in dire need of renovation.

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:

  • The type of antibiotic made me nauseous.

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.

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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 Examples

  • The building, which towered over the sightseers, gave me the shivers.
  • The building that towered over the sightseers gave me the shivers.

In the first sentence, it's the building that gave me the shivers, maybe because it featured imposing architectural details like creepy gargoyles. The fact that it towered over the sightseers is extraneous information.

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.

So it depends on the specific meaning you want to create in your sentence whether you use “which” or “that.”

Here's another example where the use of "which" and "that" completely changes the meaning of the sentence.

  • Our home, which has 4 bedrooms, is located in the Caribbean.
  • Our home that has 4 bedrooms is located in the Caribbean.

The first sentence discusses the location of your only home and it just so happens to have 4 bedrooms. Lucky you, it's in the Caribbean.

The second sentence points out that the home you own with 4 bedrooms is located in the Caribbean, which means you have more than one home, lucky dog. "That has 4 bedrooms" is how you distinguish between your many homes.

Writer’s Digest has this example that might help clarify:

“- The time machine, which looked like a telephone booth, concerned Bill and Ted.

“- The time machine that looked like a telephone booth concerned Bill and Ted.

“In the first sentence (thanks to the use of which), the time machine concerned Bill and Ted. It also happened to look like a telephone booth. In the second sentence (which uses the restrictive clause), Bill and Ted are concerned with the time machine that looks like a telephone booth. They aren’t concerned with the one that looks like a garden shed or the one that looks like a DeLorean (Marty McFly may have reservations about that one).”


Using "which" and "that" appropriately can change the meaning of your sentence in some cases. Remember our quick trick and use these words like a pro.

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The ProWritingAid Team
ProWritingAid: A grammar guru, style editor, and writing mentor in one package.

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You may want to reconsider using the word "nauseous" with the more appropriate word, "nauseated."
By writer1938 on 27 January 2017, 01:33 AM
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.
By sionnach.airgead on 19 February 2021, 10:47 PM
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! :)
By amy.cohen on 22 February 2021, 02:22 PM

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