“Which” vs. “That”: When to Use Each

Which introduces nonrestrictive clauses, whereas restrictive clauses are introduced by that.
That with a restrictive clause adds essential details and clarification, whereas which with a nonrestrictive clause adds nonessential details and context.
Use commas with which, but generally avoid them with that except in a parenthetical phrase.
Knowing how to use which and that correctly is important because these words have different meanings and thus affect sentences’ meanings.
If the details are crucial to the sentence, use that. If they aren’t crucial, use which.

Which and that are probably words you use frequently. Despite their frequency, you might not have thought much about the difference between which and that. But these words play very different roles in your writing, and sometimes, they can be confusing. Read on to learn more about using which versus that and when to use which versus that.

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Which vs. that: What’s the difference?

When to use which in a sentence

When to use that in a sentence

How to remember when to use which vs. that

Know when to use which vs. that

Which vs. that FAQs

Which vs. that: What’s the difference?

The difference between which and that depends on whether the clause it introduces is restrictive or nonrestrictive.

With a restrictive clause, use that.
With a nonrestrictive clause, use which.

So, what’s the difference between restrictive and nonrestrictive clauses? The short answer is this: A restrictive clause, also known as an essential or defining clause, contains information that’s essential to the sentence’s meaning. A nonrestrictive clause, also known as a nonessential clause, includes information that may be helpful or interesting but doesn’t impact the sentence’s meaning.

Here’s a quick example of each:

Restrictive: The literature course that I need to graduate is only offered on Fridays.
Nonrestrictive: The literature course, which covers works from a diverse collection of authors, is only offered on Fridays.

What parts of speech are which and that?

Which is a relative pronoun or a determiner. Relative pronouns are words that replace their antecedent—i.e., a noun—and that connect clauses within a sentence. A determiner is a word used before a noun to clarify it. Take a look at these examples:

Relative pronoun: Their names, which were in alphabetical order, took up two pages.
Determiner: Which ducks did you see in the pond?

That is a demonstrative pronoun, relative pronoun, adverb, conjunction, or determiner. A demonstrative pronoun is a pronoun that identifies a specific person, place, or thing. An adverb modifies another word, clause, or sentence, typically adding helpful detail. A conjunction joins clauses or sentences. Take a look at these examples of that in action:

Demonstrative pronoun: After touring the brick house, we decided we wanted to buy that one.
Relative pronoun: The notebook that I brought is red.
Adverb: Was it really that hot out yesterday?
Conjunction: They ran so fast that they wore out their shoes.
Determiner: That cake, which Bruce baked, is sugar-free.

Restrictive vs. nonrestrictive clauses

A restrictive clause is a clause that modifies a noun, and by extension its sentence, in an essential way. A nonrestrictive clause is a clause that modifies a noun in a nonessential way.

Before we go any further, let’s define clauses. A clause is a unit of a sentence that contains a subject and a predicate. In some cases, a clause can be a sentence on its own, or capable of standing on its own. These are known as independent clauses. When a clause cannot stand on its own as a sentence, it’s known as a dependent clause.

Restrictive clauses are introduced with that. Nonrestrictive clauses are introduced with which. Here are a few examples of both:

The lamp that is on my desk is a custom piece of artwork.

Our vacation, which was last October, changed my mind about cruises.

Why it’s important to use which and that correctly

Knowing how to use which and that in a sentence correctly makes your writing easier for readers to understand. It makes your meaning clearer, which reduces the likelihood of it being misinterpreted. This is especially important in academic, business, and formal writing, where clarity is a writer’s highest priority.

When to use which in a sentence

Use which in a sentence when it includes a nonessential clause. Nonessential clauses add “flavor” to sentences without changing their core meaning.

Which and nonrestrictive clauses

Which introduces nonrestrictive clauses, which add nonessential information. To determine if a clause is nonrestrictive, take it out of the sentence and see if the sentence’s meaning has changed. If it hasn’t, you’ve got a nonrestrictive clause. Here are a few examples of nonrestrictive clauses that use which.

Our bicycles, which are both blue, are in good condition for their age.

The library recently ordered new books, which patrons had been asking for.

How to punctuate which

When you use which with a nonrestrictive clause, it’s always offset from the rest of the sentence with commas.

The horse which was very friendly enjoyed eating carrots.

The horse, which was very friendly, enjoyed eating carrots.

Which doesn’t always need a comma, though. When which used in a part of speech other than a nonrestrictive clause, other punctuation marks may be correct, or it might not need a punctuation mark.

I’ve got chocolate and strawberry ice cream—which would you like?

The company offered two compensation structures: which do you think the union will choose?

Which, package is yours?

Which package is yours?

Examples of which in sentences

“By three methods we may learn wisdom: first, by reflection, which is noblest; second, by imitation, which is easiest; and third, by experience, which is bitterest.” —Confucius

Our company, which had never won an award before, was nominated for Best Tech Startup.

Which song did you choose for your video?

Here’s a tip: If you’re not sure if a sentence needs that or which, Grammarly can help. Grammarly proofreads your work to catch mistakes and make helpful suggestions to help your writing shine.

When to use that in a sentence

There are lots of ways to use that in a sentence. In this post, we’re primarily discussing restrictive and nonrestrictive clauses, but it’s important to remember that that can also be a demonstrative pronoun, determiner, relative pronoun, adverb, or conjunction. In any case, that introduces key information that affects the sentence’s meaning.

That and restrictive clauses

A restrictive clause is essential to a sentence’s meaning. Use that when introducing a restrictive clause. Here are a few examples of that used with restrictive clauses:

My bike that has a broken seat is in the garage.

The class that collects the most cans will win a pizza party.

Notice how in these sentences, that narrows down information or specifies meaning. If we swapped in which, these sentences would read very differently.

My bike, which has a broken seat, is in the garage.

The class, which collects the most cans, will win a pizza party.

See how the first example now makes the bike’s broken seat feel like a detail, rather than the reason why it’s in the garage? Or how the second example doesn’t make much sense now? That’s because in these sentences, the restrictive clause is crucial to their meaning.

How to punctuate that

Unlike nonrestrictive clauses, restrictive clauses are not offset by commas. When you use that with a restrictive clause, no additional punctuation is needed.

However, when that is used in other ways, additional punctuation may be necessary. One example is sentences where that introduces a parenthetical phrase. A parenthetical phrase is a phrase that adds information to a sentence without affecting the sentence’s structure. It may be offset by parentheses, commas, or dashes.

The judge reconsidered his initial ruling (that we’d hoped he’d reconsider).

So, what’s the difference between a parenthetical phrase and a nonrestrictive clause? Almost nothing. Functionally, they’re basically the same thing. One difference is that a parenthetical phrase can be a single word or just a few words, unlike a nonrestrictive clause, which must contain a subject and a predicate.

When you use that to introduce a parenthetical phrase, close the phrase with a comma.

The book, that was lying on the table, belongs to Sarah.

In other cases, that may follow a colon or dash.

We can’t stop now—that wouldn’t be fair to the team.

I set out six settings for the dinner party; that was the maximum number I could accommodate.

Examples of that in sentences

“The music that can deepest reach, / And cure all ill, is cordial speech.” —Ralph Waldo Emerson, The Conduct of Life

“To be bitter is to waste precious moments of a life that’s too short already.” —H. Jackson Brown Jr., P.S. I Love You

Remember that time we stayed up all night reading comic books?

The grasshoppers escaped last night. That can’t happen again.

How to remember when to use which vs. that

Because nonrestrictive clauses add removable information, it’s easy to remember to use which if you think of the paper that a sandwich comes wrapped in. It is disposable, and so are clauses with which.

For clauses that aren’t disposable, use that. You can also use this guide when you’re stuck between using that and which as a pronoun.

Common mistakes to avoid with which and that

One common mistake that writers often make is using which without a comma, as in this example:

Her dress which was black made it difficult to see her in the dark.

Her dress, which was black, made it difficult to see her in the dark.

A similar error many writers make is using a comma with that:

He lent me a book, that I needed for class.

He lent me a book that I needed for class.

Another common error is overusing that in formal writing. Whether you’re writing in a formal, professional, or casual tone, the same grammatical rules apply. Use that when it’s necessary and correct, such as when that introduces a restrictive clause or acts as a demonstrative pronoun. Otherwise, remove any instances of that that aren’t needed. Here are a few examples:

Awkward: Climate change is an issue that can be divisive.
Better: Climate change can be a divisive issue.

Awkward: They promised that they would consult the whole team in the future.
Better: They promised to consult the whole team in the future.

Know when to use which vs. that

Which and that are two distinct, equally important words to use in your writing. While which introduces details that make a sentence more interesting, that adds crucial information that can change the sentence’s meaning. They can also both serve as pronouns, reducing redundancy. In the pronoun role, which still introduces nonessential information while that introduces essential information.

Knowing how to use which and that correctly is a valuable skill that will make you a stronger writer. If you’re ever unsure of which is correct in a sentence, Grammarly can help by providing suggestions and catching mistakes in your writing.

Which vs. that FAQs

What’s the main difference between which and that?

The main difference between which and that is that which introduces nonessential information and that introduces essential information. Put another way, clauses that begin with which add interest, but don’t change a sentence’s meaning. Clauses that begin with that do change a sentence’s meaning.

Can you use which and that interchangeably?

No, you cannot use which and that interchangeably. Which and that have distinct meanings, and although there is some overlap in the parts of speech they play, they have different grammatical purposes.

How do you use commas with which and that?

Nonrestrictive clauses, the clauses that incorporate which, are offset from the rest of their sentences with commas. Restrictive clauses, which incorporate that, are not offset with punctuation.

What’s an easy way to remember how to use which vs. that?

The easiest way to remember whether to use which or that in a sentence is to remove the clause that contains which or that and see if it changed the sentence’s meaning. If it did, use that. If it did not, use which.