Get the grammar rules for using that and which.
There’s a lot of confusion about that and which. These two words are often used interchangeably, even though they’re not necessarily interchangeable.
Historically, that and which may have carried the same meaning, and some English dialects may allow for that and which to be swapped without affecting the meaning of a sentence.
However, in American English, the grammar rules offer a distinct difference between the two words. By the time you’re done reading this post, you’ll fully understand the difference between that and which, and you’ll be able to use both words correctly.
That and Which
As with most grammar rules, there are exceptions and exemptions from the standard ways that and which should be used in a sentence. To gain understanding of confusing word pairs, it’s always best to start with the basics. As we look at how to properly use that and which, we’ll focus on simple, standard usage.
That and which can be categorized into several different parts of speech. Both words can function as adjectives and pronouns. Additionally, that can serve as a conjunction and as an adverb. Today, we’re looking at how that and which should be used when they are working as relative pronouns.
That vs. Which
The standard rule of grammar is that the usage of that vs. which depends upon whether the following clause is restrictive or non-restrictive.
“That” is used to indicate a specific object, item, person, condition, etc., while “which” is used to add information to objects, items, people, situations, etc. Because “which” indicates a non-restrictive (optional) clause, it is usually set off by commas before “which” and at the end of the clause.
The general rule requires that you use that only to introduce a restrictive (or defining) relative clause, which identifies the person or thing being talked about. For example,
The building that I was telling you about is just down the road.
In this sentence, the phrase that I was telling you about specifically identifies the object in the previous phrase (building) and is a restrictive clause. In this use, that should never be preceded by a comma because the word is an integral (non-optional) part of the description.
Similar examples include:
- My books that have red covers are new.
- The classes that are held every Monday start at 9:00 AM.
Note that the subject of the restrictive clause can change “that” to “who”, “when” and “where” for correct usage. Use who for a person, when for a time period and where as a substitute for “that place”. For example:
- The man who shot Lincoln jumped onto the theater's stage.
- Remember the time when I fell off the ladder?
- Billy went to where they sell turkey eggs.
Rule for using Which instead of That
On the other hand, use which with non-restrictive (or non-defining) clauses. These are clauses providing additional information about something that has already been identified in the context. In this use, which is always preceded by a comma and a comma is placed after the restrictive clause ends (if the sentence continues). For example,
- My new books, which have black covers, are on the desk.
- The padded chairs, which are on the second floor, have to be replaced.
When the clause is at the end of the sentence, only one comma is used, before which:
The students in Chemistry 101 have been complaining about the textbook, which is hard to follow.
In this case, the clause which is hard to follow is descriptive, not restrictive i.e. it does not specify which text is being complained about (although it can be easily inferred). For these cases, which sounds more natural than that.
Some grammarians extend the rule and insist on that being used only in restrictive clauses, while which should be used only in nonrestrictive clauses. For example:
Wrong, according to strict grammarians: I need a book which will tell me all about city gardening.
Correct usage: I need a book that will tell me all about city gardening.
The use of which with restrictive clauses is fairly common, even in edited prose. However, the American Psychological Association (APA), in its 6th edition Manual, recommends adhering to the rule and use that for all restrictive clauses.
Which can be especially useful where two or more relative clauses are joined by and or or. For example,
Politics is an environment in which ordinary people may succumb to greed and which many have found reason to hate.
You may also want to use which to introduce a restrictive clause when the preceding phrase contains a that or a those. For example,
- We want to fund only those initiatives which will increase revenues and customer satisfaction.
That vs. Which
One of our readers, Justin, recently wrote to ask:
When proofreading a peer’s article on the solar system, I realized that she, and I, are unsure of the proper use of “that” and “which” in a sentence. Below is [SIC] two examples of the same sentence, one using “that” and the other “which.”
- “To our knowledge, it is the only body in the solar system which currently sustains life, although several other bodies are under investigation.”
- “To our knowledge, it is the only body in the solar system that currently sustains life, although several other bodies are under investigation.”
Which is the correct sentence, and what is the general rule of thumb?
Justin, I’ll give you the answer now, rather than making you read to the end of the whole article: the second version of that sentence, using that is correct.
When To Use “That” and When To Use “Which”
Before I come on to the “that”/”which” rule, just a reminder that “who” should always be used when referring to people.
- The boy who threw the ball.
- This is the woman who always wears a black shawl.
When referring to objects, though, the rule for using “that” and “which” correctly is simple:
- THAT should be used to introduce a restrictive clause.
- WHICH should be used to introduce a non-restrictive or parenthetical clause.
If that leaves you more confused than when you began this article, read on…
A restrictive clause is one which is essential to the meaning of a sentence – if it’s removed, the meaning of the sentence will change. For example:
- Chairs that don’t have cushions are uncomfortable to sit on.
- Card games that involve betting money should not be played in school.
- To our knowledge, it is the only body in the solar system that currently sustains life…
A non-restrictive clause can be left out without changing the meaning of a sentence. Non-restrictive clauses are either in brackets or have a comma before and after them (or only before them if they come at the end of a sentence):
- Chairs, which are found in many places of work, are often uncomfortable to sit on.
- I sat on an uncomfortable chair, which was in my office.
Why You Need to Use “That” or “Which” Correctly
Changing that to which or vice versa can completely change the meaning of a sentence. Consider the following examples:
- My car that is blue goes very fast.
- My car, which is blue, goes very fast.
The first sentence uses that – suggesting I own more than one car (and even implying my other cars might not be so fast). This is what happens if we leave out the clause and write:
- My car that is blue goes very fast.
- My car goes very fast.
The sentence’s meaning has changed: the reader does not know which one of my cars goes very fast.
However, the sentence using which simply informs the reader that my car is blue. We can take the clause out without losing any essential information:
- My car, which is blue, goes very fast.
- My car goes very fast.
“That” and “Which” in Common Usage
It is common today for which to be used with both non-restrictive and restrictive clauses, especially in informal contexts:
- Who ate the cake that I bought this morning?
- Who ate the cake which I bought this morning?
The clause “that I bought this morning” is essential to the meaning – I’m not asking about a cake which I bought yesterday, or this afternoon. Therefore, the first example using “that” is the correct one, but many people would not consider the second ungrammatical.
It is, however, incorrect even in informal contexts to use that for a non-restrictive or parenthical clause. For example, these sentences would be considered incorrect:
Which vs. That: What’s the Difference?
If you aren’t sure when to use which vs. that in your writing, don’t feel bad. They are one of the most common questions I get from readers, wondering when it is correct to use which word.
Which and that are both complicated words in English with many different uses inside a sentence. And while they both can be used in other constructions, the confusion between the two usually centers on their uses as relative pronouns. If you’re not sure what these are, don’t worry; everything you need is explained below.
What is the Difference Between Which and That?
Many people say the differences between these two words aren’t really differences at all. Still, many people yet swear by the traditional rule I will outline below.
That and Which as Pronouns
A brief, important note on using which or that as pronouns: be careful when using them to refer to people. Many style guides specify writers to solely use who when referring human beings and/or animals with a name. For example,
- The woman who opened the door for you is my mom. (CORRECT)
- The woman that opened the door for you is my mom. (WRONG)
Which and that are used, instead, for inanimate objects or animals without a name. For example,
"Which" or "That": Know When to Use Each
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.
- 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?
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.
- 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.
- The building, which towered over the sightseers, gave me the shivers.
- The building that towered over the sightseers gave me the shivers.
Who, That, Which
Rule 1. Who and sometimes that refer to people. That and which refer to groups or things.
Examples: Anya is the one who rescued the bird. “The Man That Got Away” is a great song with a grammatical title.
Lokua is on the team that won first place.
She belongs to a great organization, which specializes in saving endangered species.
Rule 2a. That introduces what is called an essential clause (also known as a restrictive or defining clause). Essential clauses add information that is vital to the point of the sentence.
Example: I do not trust products that claim “all natural ingredients” because this phrase can mean almost anything. We would not know the type of products being discussed without the that clause.
Rule 2b. Which introduces a nonessential clause (also known as a nonrestrictive or nondefining clause), which adds supplementary information.
Example: The product claiming “all natural ingredients,” which appeared in the Sunday newspaper, is on sale.The product is already identified. Therefore, which appeared in the Sunday newspaper is a nonessential clause containing additional, but not essential, information.
Essential clauses do not have commas introducing or surrounding them, whereas nonessential clauses are introduced or surrounded by commas.
Rule 3. If that has already appeared in a sentence, writers sometimes use which to introduce the next clause, whether it is essential or nonessential. This is done to avoid awkward formations.
Example: That which doesn't kill you makes you stronger. This sentence is far preferable to the ungainly but technically correct That that doesn't kill you makes you stronger.
The distinction between that and which, though a useful guideline, is not universally accepted as a hard-and-fast rule. For many centuries and up to the present, which has been routinely used by great writers and journalists to introduce essential clauses.
Are you ready for the quiz?
Which or That?
While both which and that can be used in other constructions, the confusion usually arises when they are being used as relative pronouns to introduce adjective (or relative) clauses. In the examples below, we have bracketed the adjective clauses. (Remember that a clause is simply a group of words containing a subject and a verb.):
- Our house [that has a red door and green shutters] needs painting.
- Our house, [which has a red door and green shutters], needs painting.
- The classrooms [that were painted over the summer] are bright and cheerful.
- The classrooms, [which were painted over the summer], are bright and cheerful.
In all four cases, the adjective clause tells us something about either the house or the classrooms, but the choice of which or that changes the way we should read each sentence.
How They Differ in Meaning
In the first sentence, the use of that suggests that we own more than one house and therefore must explain to you that we are talking about a particular house of ours—the one with a red door and green shutters.
We cannot leave out that adjective clause because it is essential to your understanding of the sentence; that is, you wouldn’t know which one of our houses needs the paint job without that clause, without that information.
The second sentence tells you that we own only one house and we are simply telling you—in case you want to know—that it happens to have a red door and green shutters. We could leave out the information in that adjective clause and the sentence would still make sense.
The third sentence, because it uses that to launch its adjective clause, tells us that only SOME of the classrooms were painted over the summer.
If we omitted the clause “that were painted over the summer,” we would be left with “The classrooms are bright and cheerful,” a statement that would not be accurate since it would imply that ALL the classrooms are bright and cheerful.
In this sentence, therefore, the adjective clause is essential to the meaning of the sentence.
“That” Clauses Are Restrictive/Essential
We call the adjective clauses in sentences one and three essential or restrictive because they restrict—or limit—the meaning of the nouns they modify. In the case of sentence three, they tell us that we are talking ONLY about the classrooms that were painted over the summer—not the others.
“Which” Clauses Are Nonrestrictive/Nonessential
The which clause in the fourth sentence is what we call a nonessential—or nonrestrictive—clause. Since that sentence intends to tell us that ALL the classrooms were painted, the information in the adjective clause is not essential. That is, the sentence would be clear even type if the clause were omitted.
The rule of thumb, then, is that which clauses are nonrestrictive (nonessential) while that clauses are restrictive (essential).
And They Need Commas
Nonrestrictive clauses and phrases are set off from the rest of a sentence by a pair of commas (as in our examples above) or by a single comma if they come at the end of the sentence. (Example: “I took a vacation day on my birthday, which happened to fall on a Monday this year.”)
Not Everyone Understands
Merriam-Webster’s Collegiate Dictionary, regarded by most writers as the authority on such matters, tells us that it is now common for which to be used with either kind of clause, while that must be used only for restrictive clauses. In fact, though, careful writers continue to make the distinction described above.
This Distinction Is Important in Legal Contexts
Attorneys are taught to use which for nonrestrictive clauses and that for restrictive clauses so as not to cause a misreading in legal documents. It seems just as important that we work to avoid misreadings in all writing, not only in situations when a legal ruling might be at stake.
One Final Point
Remember that we should use who and whom instead of which or that in reference to people (and animals with names, such as pets):
- These are the students who [NOT that] just finished their exams.
- Everyone who [NOT that] came to my house for dinner brought food to share.
- The technician whom [not that] I called this morning was at my house by noon.
Which pronoun—which or that—belongs in each blank below?
- Carlos gave Maria a study guide for material ________ was going to be on the test.
- Carlos gave Maria notes from chapters 3 through 7 _________ were going to be on the test.
- Mark and Sarah took their children on every vacation _________ they took to the coast.
- The teachers gave awards to all paintings ________ showed originality.
- Carlos gave Maria a study guide for material that was going to be on the test. [To say simply “Carlos gave Maria a study guide for material” would not be complete information. We need the adjective clause to tell us which material, in particular.
Since the information is, therefore, essential, we use that and no comma.]
- Carlos gave Maria notes from chapters 3 through 7, which were going to be on the test.
[The fact that chapters 3 through 7 were going to be on the test is not essential to our understanding exactly which notes Carlos gave Maria, so we use a comma and which.]
- Mark and Sarah took their children on every vacation that they took to the coast.
[If we said simply “Mark and Sarah took their children on every vacation,” we would be inaccurate. The information in the adjective clause is essential to our understanding that the children went on certain vacations and not others. Therefore, we use that and no comma.
- The teachers gave awards to all paintings that showed originality. [To say simply “The teachers gave awards to all paintings” would be inaccurate. The information in the adjective clause is, therefore, essential to the meaning of the sentence, so we use that and no comma.]
©2000 Get It Write. Revised 2003 and 2019.
APA Style 6th Edition Blog: That Versus Which
- by Tyler Krupa
- This week, we address another item on the list of frequent APA Style points that writers find most challenging (on the basis of the article by Onwuegbuzie, Combs, Slate, & Frels, 2010; also see their guest post to our blog): the use of that instead of which.
According to the 6th edition of the APA Publication Manual (p. 83), APA prefers for writers to use the term that for clauses that are essential to the meaning of the sentence. These types of clauses are referred to as restrictive clauses. The term which should be used for clauses that merely add further information to the sentence that is not essential to its meaning. These types of clauses are referred to as nonrestrictive clauses and should be set off with commas.
To help clear up any confusion regarding the proper use of these terms, let’s begin with looking at some examples of that being used correctly:
|It is important to include additional predictors of alcohol or other substance use disorders that were present before treatment. A poor economy can create and stimulate forces that operate at multiple levels of a society to influence those operating within it. One way to predict who may benefit from posttraumatic stress disorder treatment is to investigate variables that impact naturalistic recovery.|
Note that in each example above, the meaning of the sentence is not properly conveyed if the that clause is not included. These clauses are essential to understanding the sentences and therefore are restrictive.
Now for comparison, let’s look at some examples of which being used correctly:
|In the Level 2 equations, the r terms represent random effects, which describe provider variation for the intercept and various client effects. Binge eating disorder symptom counts, which are identified in Figure 2, were used at each time point. One key difficult child characteristic is hyperactivity/impulsivity, which has been proposed to contribute to the development of oppositional defiant disorder by eliciting negative family functioning.|
Note that in these examples, if you remove the which clause from the sentences, the meaning of each sentence is still conveyed. The which clauses are just providing additional information to the reader and therefore are nonrestrictive.
Consistent use of that for restrictive clauses and which for nonrestrictive clauses will help make your writing clear and precise. If you still have questions regarding the proper use of these terms after reviewing the examples above, feel free to leave a comment, which we will reply to as soon as possible.
World Wide Words: Which versus that
To judge from correspondence, people are confused about which and that and, especially, which one to use when introducing clauses that modify nouns. This isn’t surprising, as there has been a shift in usage over the past century or so and older guides give different advice from newer ones.
The usage is intimately tied up with the distinction that grammarians make between two types of clause, which they call restrictive and non-restrictive. A restrictive clause is one that limits, or restricts, the scope of the noun it is referring to. Take these examples:
The house that is painted pink has just been sold. The house, which is painted pink, has just been sold.
In the first one, the clause “that is painted pink” is a restrictive clause, because it limits the scope of the word “house”, indicating that the writer doesn’t mean any house, only the one that has been painted in that particular colour; if he takes that clause out, all that’s left is The house has just been sold: the reader no longer knows which house is being referred to and the sentence loses some crucial information. In the second example the clause is non-restrictive: the writer is giving additional information about a house he’s describing; the clause which is painted pink is here parenthetical — the writer is saying “by the way, the house is painted pink” as an additional bit of information that’s not essential to the meaning and could be taken out.
Here’s another example:
Which vs That! ???? Is there a Difference Between Which and That?
Well that depends, there is no difference in meaning but there is a difference in the way we use it. There are various ways to use both. However, we are going to look at how they work as relative pronouns.
To start with, we use “that” when we refer to people, animals, and things. We use “which” when we refer to animals and things.
However, the main difference between both depends on the clause. Is the clause restrictive or non-restrictive?
If the clause is restrictive, you need to use the relative pronoun that, without it, the meaning would be unclear.
- The car that he bought is very expensive.
You would use the pronoun which when a clause is non-restrictive. Meaning that you are not being specific but instead you are adding extra information to a sentence. A comma usually accompanies this as it denotes a pause in speech and it always precedes which.
Check your Grammar ››
- He bought a car, which is very expensive.
There is one exemption where it is possible to use “which” in a restrictive clause when preceded by a preposition.
- The car in which I came was very expensive.
???? When to Use Which vs That?
Correct use of that or which, depends on identifying the clause as restrictive or non-restrictive. If the clause is restrictive, use the relative pronoun that.
For clauses that are non-restrictive use the pronoun which. Do not forget about the exemption to the rule; you can use which in a restrictive clause when preceded by a preposition.
Both which and that can function as relative pronouns. That is only used in defining relative clauses while which can be used in both defining and non-defining clauses.
That can be used to refer to both objects and persons.
Which is not used for persons.
- The girl that you saw at the party is my sister. (defining clause)
- I’ve never read the book which is on the table. (defining clause)
- Pride and Prejudice, which was written by Jane Austen, is a great novel. (non-defining clause)
In a non-defining clause, which can refer to either a word or the whole meaning of the main clause:
- We love spending our holidays in my aunt’s house, which is by the seaside.
- One of the weakest jockeys came first in the horse race, which was a surprise to everyone.
In a defining clause, both that and which can occur:
- Please give me the book that my sister lent you last week.
- Please give me the book which my sister lent you last week.
However, only that (or the zero pronoun) should be used with reference to
Conditionals in English: First, Second, Third, Zero and Mixed
1. indefinite pronouns or structures with indefinite pronouns:
- Everything that you do will be remembered.
- She cooked all the potatoes that were in the basket.
- I’ll tell you something that will shock you.
- I can’t find some of my T-shirts; I wish I could find the one that has yellow sleeves.
- The police examined each bag that was left in the locker.
2. superlative adjectives or phrases with superlative adjectives:
- This is the best film that I’ve ever seen.
- The most important thing that you must always keep in mind is honesty and hard work.
3. (phrases with) ordinal numbers:
- A book is the first that I would take to a desert island.
- The third excursion that we made in the mountains was a failure.
4. the only…, thing, etc.
- The only music that
When to Use Which or That
When to use which or that is one of the most grammatically confusing grammar lessons ever taught.
The fact that the two words are considered practically interchangeable in modern English does not make learning the distinction between the two much easier.
You could sit through four years of English classes and still not fully understand when to use “which” or “that.” Hopefully, the illustrations below will help you.
The elements up for illustration are not earth, wind or fire. Let's talk sentence elements. They are restrictive and non-restrictive elements.
- A restrictive element is a word, phrase or a clause that manages to limit the meaning of the sentence element that it modifies. When a restrictive element is not included then the entire meaning of the sentence will change.
- The non-restrictive element is a word, phrase or a clause that provides excess information about the beginning of a sentence without restricting the meaning of that part of the sentence.
Keep these two definitions in the back of your mind because they will be crucial in understanding when to use “which” or “that.”
The word “that” is considered to be a restrictive element of any sentence that it may be used in.
Look again at the definitions above – a restrictive element limits the meaning of the sentence element that it modifies. For example, in the sentence, “Baby foods that contain soybeans are best,” the restrictive element of the sentence are the words “that contain.” These words restrict the type of baby food that is being discussed.
In effect, without the words “that contain” the whole sentence meaning would be altered. In fact, there would be no restrictive element of the baby food. Instead the sentence would imply that all baby food is best.