Which vs. That — How to Use Them Correctly

In English grammar, the use of the relative pronouns ‘which’ and ‘that’ is similar when introducing a clause, however, there are a few key differences.

In this guide, we’ll review when it’s best to use ‘which’ and when you should use ‘that,’ so you can avoid common grammar mistakes and communicate clearly with your audience.

Then, review your copy with the Originality.ai Grammar Checker to identify and correct any grammar or spelling mistakes.

Restrive and Nonrestrictive Clauses: A Brief Overview

In order to understand whether to use ‘which’ or ‘that,’ it is necessary to know the difference between restrictive and nonrestrictive clauses. 

Walden University notes that a restrictive clause provides essential context and information about the noun in the sentence. When writing a restrictive clause you don’t use a comma to isolate it in a sentence.

Then, a nonrestrictive clause gives additional information about the noun. What differentiates it from a restrictive clause is that this information is not essential and you can separate it in the sentence with a comma. You can still understand the meaning of the sentence without a nonrestrictive clause.

Now let’s dive into the differences between ‘which’ and ‘that.’  

When to Use ‘Which’ in a Sentence

Merriam-Webster Dictionary notes that it is grammatically correct to use ‘which’ to introduce either a restrictive or a nonrestrictive clause when writing a sentence. 

However, to reduce confusion when deciding between ‘which vs. that,’ ‘which’ is often only used with nonrestrictive clauses.

For example, let’s take a look at restrictive clauses that could use ‘which’:

• I visited the museum which displays ancient artifacts.
  
  • Alternative for clarity: I visited the museum that displays ancient artifacts.
• The documentary which covers climate change impacts is very informative.
  
  • Alternative for clarity: The documentary that covers climate change impacts is very informative.

Remember, when introducing a nonessential clause, use a comma to separate the clause from the rest of the sentence.

Examples of nonrestrictive clauses with ‘which’: 

• The novel, which featured a female protagonist, was nominated as a best seller.
• The house, which was built in 1865, is now a historical landmark.
• My laptop, which I bought last year, is already in need of repairs.

When to Use ‘That’ in a Sentence

When writing a sentence use ‘that’ to introduce a restrictive clause. 

A key difference between ‘that’ and ‘which,’ is that unlike ‘which,’ you cannot use ‘that’ in a nonrestrictive clause. Additionally, you don’t use commas with restrictive clauses using ‘that.’ 

Examples of Restrictive Clauses with ‘that’:

• The café that opened last month has already become very popular.
• The squirrel that was in the park climbed up the tree.

When to Use ‘Which’ or ‘That’

There are several instances where you might find that either ‘that’ or ‘which’ are both options.

However, word choice can alter the sentence’s meaning, so don’t treat the two as interchangeable. 

Example Using ‘Which’ or ‘That’:

• Sage’s favorite café, which serves cappuccinos, is on Second Street.
  
  • The use of ‘which’ implies that the café on Second Street is Sage’s favorite café and it happens to serve cappuccinos.
• Sage’s favorite café that serves cappuccinos is on Second Street.
  
  • The use of ‘that’ changes the meaning to refer to all cafés that serve cappuccinos, and specifies that Sage’s favorite cappuccino-serving café is on Second Street.

In general, use ‘which’ to share additional information about a specific item. 

Then, for ‘that,’ our restrictive clause provides essential information to differentiate the subject from other similar items (e.g., one of Sage’s favourite cafés).

Final Thoughts

Deciding whether to use ‘which’ or ‘that’ is a common cause of confusion in grammar. Choosing the correct pronoun, ‘which’ or ‘that’ is impacted by whether you are writing a restrictive or nonrestrictive clause, and can also influence the meaning of the sentence.

Review your content to make sure you are using ‘which’ or ‘that’ correctly with the Originality.ai Grammar Checker.

Then, read our top grammar guides to get more tips on how to improve your writing:

• What Is a Predicate? A Comprehensive Guide
• It’s vs. Its — How to Use Them Properly + Examples
• What are Run-On Sentences?
• Sentence Fragments — A Comprehensive Guide