When is it appropriate to use that as opposed to which with relative clauses?

  • 6
    I heard a story once about someone copy-editing something by Alfred Tarski. They had switched every occurrence of "that" and "which", since they considered that Tarski had got them completely the wrong way round. Tarski sent back the manuscript with all the occurrences of "that" and "which" swapped back again.
    – Seamus
    Commented Sep 6, 2010 at 14:12
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    I am a native speaker and I confess I don't know either; the only time I ever notice it is when using a certain Microsoft product, and I always do what it suggests just to get rid of those damned green squiggles. Commented Mar 5, 2011 at 11:36
  • 5
    @Brian Hooper: This is precisely why I turn off the grammar checking in Word. I still write however I want, but it bothers me that a software program doesn't approve. I guess that's one definition of neurosis.
    – Robusto
    Commented Mar 5, 2011 at 12:13
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    Wish I could up-vote the question twice; this is something that always gets me as well, and I never seem to remember the rules governing the use of the two words.
    – Will
    Commented Mar 5, 2011 at 12:47
  • 9
    this made me think of, "That which does not kill me makes me stronger"
    – iamserious
    Commented Apr 13, 2011 at 14:00

14 Answers 14


That and which are interchangeable when introducing integrated relative clauses. Although some grammar mavens (i.e., people who hold forth on such topics but know little or nothing about linguistics) and copy editors will insist otherwise, the rule is completely bogus.

See, for instance, Language Log on that vs which, written by the co-editor of The Cambridge Grammar of the English Language.

Practically speaking, it is not something that any normal person will generally notice or follow in spoken English and it's frequently — and rightly — ignored even in literary writing. So even from that point of view it's not worth worrying about.

  • 5
    Three cheers for Language Log! Commented Aug 9, 2010 at 2:25
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    Thanks for the link and the answer. I had been wondering about the distinction some people claim (but I had never learned in English classes), and your answer allowed me to understand the issue better. Commented Dec 9, 2010 at 18:32
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    -1, I hate this answer. There is a difference between that and which in that the latter is nonrestrictive.
    – Jez
    Commented Aug 17, 2012 at 21:21
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    @Jez: There is a difference between that and which in that the latter may be used grammatically to mark a nonrestrictive relative clause, and the former may not. In restrictive clauses, of course, both are grammatical. Commented Feb 10, 2013 at 17:19
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    -1 The most useful information here would surely be that that *CAN'T be used in non-defining clauses!!! (you edit it and I'll upvote it!) Commented Jun 14, 2014 at 19:29

Well, the difference is slight but real. According to the New Oxford American Dictionary:

In U.S. English, it is usually recommended that which be employed only for nonrestrictive (or nonessential) clauses: the horse, which is in the paddock, is six years old (the which clause contains a nonessential fact, noted in passing; the horse would be six years old wherever it was). A that clause is restrictive (or essential), as it identifies a particular thing: the horse that is in the paddock is six years old (not any horse, but the one in the paddock).

Note also that the word that can be omitted where it introduces a subordinate clause:

He said he was coming. [He said that he was coming.]

But it is required when it is the subject of the clause:

The family that plays together stays together.

More usage notes from NOAD:

Is there any difference between the use of that and which in sentences such as any book that gets children reading is worth having, and any book which gets children reading is worth having? The general rule is that, in restrictive relative clauses, where the relative clause serves to define or restrict the reference to the particular one described, that is the preferred relative pronoun. However, in nonrestrictive relative clauses, where the relative clause serves only to give additional information, which must be used: this book, which is set in the last century, is very popular with teenagers, but not this book, that is set in the last century, is very popular with teenagers.

  • which of the following would be right? or do they have different meanings? 1. Use the interface that provides access. 2. Use the interface which provides access.
    – Lea Hayes
    Commented Jul 26, 2011 at 2:49
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    @Lea: #1 urges you to use whichever interface provides access. #2 says the interface in question does provide access. Also, #2 should have a comma after interface to make clear that you don't mean it in the restrictive, relative sense.
    – Robusto
    Commented Sep 10, 2011 at 13:35
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    simplest way for me to remember this is: use "which" to tell that; use "that" to tell which. In other words, use "which" to provide additional (non-essential) information, and use "that" to specify which one.
    – user428517
    Commented Jan 22, 2014 at 22:41
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    It's useful to distinguish British from American usage, here. The OED considers them "equally correct" for restrictive relative clauses oxforddictionaries.com/words/that-or-which. Being an American, I prefer the finer distinctions afforded by the NOAD in this answer.
    – Reb.Cabin
    Commented Jul 7, 2015 at 16:28
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    @user405662: In my view, you do need a that in "The horse [that] raced past the barn fell."
    – Robusto
    Commented Apr 5, 2021 at 12:34

Actually, there's more to this than mentioned in some other answers. The word that is a subordinator; it is not a relative word like who, where, when, or which. Even in integrated relative clauses, they are not always interchangeable. When the relative construction follows a fronted preposition, only relative words will do, so relative pronoun which is available, but that isn't.

We have to protect the environment in which we live.

No art can be properly understood apart from the culture of which it is a part.

Conversely, when the relative clause is post-modifying superlatives, we can choose between that or no subordinator, but which is not possible:

He's the best (that) I've ever seen.

He's the fastest runner (that) I've ever seen.

Also in cleft sentences with prepositional phrases like the following, only that is available.

It wasn't for you that I bought it.

It was from John that she heard the news.

Finally, which usually cannot be used where other relative words would work, but that typically can:

They gave the prize to the girl that spoke first. [who]

He was to leave at the time that she arrived. [when]

They looked every place that she could be. [where]

That's not the reason that she resigned. [why]

I like the way that she plays. [*how]

  • 2
    A great way to explain the differences; the examples are the best I could ask to clarify the point.
    – Kris
    Commented Dec 20, 2011 at 14:50
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    I would say that for the last batch of examples, which would be marginally grammatical though awkward for me—more for some than others. It seems that which can substitute more easily for when, where, and why than for who and how
    – nohat
    Commented Jan 24, 2012 at 7:17
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    In today's enlightened times, even an inherently good answer on ELU is deemed sub-optimal without linked, attributed supporting reference/s. Commented Apr 2, 2020 at 10:53
  • Way, reason, place and time are all exceptional nouns which behave oddly when it comes to relative clauses *That's the restaurant that I met my wife won't work even though its integrated and would be grammatical with where, for example. Commented Oct 31, 2022 at 11:16

Generally, "that" goes with restrictive clauses - those where the information provided in the clause is necessary to identify the subject: "The beer that belongs to me" (as opposed to all other beers in the world).

"Which" goes with non-restrictive clauses - those which give information but which do not define the subject: "The beer, which was a little warm, was still tasty."

  • 13
    +1. But as the Language Log (or any sensible grammar book really) points out, "which" is also acceptable in restrictive clauses: "the beer which belongs to me" is fine. But it's definitely wrong to use "This beer, that was a still warm, was …". Commented Aug 6, 2010 at 0:23

It's not the most authoritative/formal source ever, but the grammar book Woe is I provides an easily remembered rule of thumb that has stuck with me through the years:

"Commas, which cut out the fat, go with which, never with that."

  • 3
    +1 for Woe is I, which is a great guide to "most grammar issues that still confuse well-educated people". And because I still use this rhyme from it to remember this particular issue.
    – Jaydles
    Commented Aug 17, 2010 at 2:16
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    Yikes, that book doesn't know about "singular they"!? books.google.com/… Commented Sep 24, 2010 at 18:27

In this particular case, either 'which' or 'that' is grammatical.

In general, 'which' and 'that' are interchangeable when referring to something inanimate.

The main restriction is that that is not usually used to introduce a so-called "non-restrictive relative" (essentially, relative clauses where a pause is obligatory between the relative clause and the surrounding sentence).

However, in your case, the relative clause is of the "restrictive" type and speakers would use either 'that' or 'which' fairly interchangeably.


My answer comes so late that it is probably doomed to dwell at the bottom of the answer column, but the question remains a question about which I care, so my answer adds a point other answers have missed.

"Which" instead of "that" is almost always used in sentences with nonrestrictive qualification, as

The horse, which is in the paddock, is six years old.

The horse would still be six years old even if it were in the stable, see? Alternately and more to the point, there seems to be no second horse in view; there is no four-year-old horse about that might (which might?) also concern us.

As other answers have noted and as NOAD has advised, American English slightly, abstractly prefers the word which—as a conjunctive pronoun—to be reserved for this nonrestrictive use.

However, the best American writers have not uniformly followed NOAD's advice. Peggy Noonan does indeed follow it (with no recent exception I have observed):

My thought, which is really a question, is that candidates for president, while natural competitors, sometimes get to the point where they think they are going to win, and it messes with their heads.

John Steinbeck however does not:

The mattresses which had been on the floor were gone.

Even if you are of the rigid, conservative, antidemocratic school of proper usage, as I tend to be, it is hard to argue with Steinbeck. Nor is Steinbeck the only one.

NOAD's advice, quoted in another answer, is fine as far as it goes. NOAD is correct. NOAD should be heeded. However, there is more to the story than NOAD tells.

The trouble with the conjunctive pronoun that is that that is not just a conjunctive pronoun. It is a word with too many uses for its own good—too many uses, even in this very paragraph. The word that is a word which (a word that?) serves so many roles, in various parts of English speech, that the less frequent word which makes a welcome change. In the usage of which versus that, the euphonic has trumped the strictly logical.

Germanic languages are sometimes like that. Can't help it. It's in the bones of the language. English is not like Greek.

In short, heed NOAD's advice by default, but where which sounds better than that—as in complex sentences it often does, and even sometimes in simple sentences like Steinbeck's—even if you are American, feel free to switch to which.

You may often find cause to switch.

  • @sumelic: If you have time, would make the suggested edits? I had not known that all languages are like that. In particular, I had thought that the peculiar usage of "das" and its cognates was a Germanic thing -- unlike, say, "qua," whose cognates are not used in such a way. But my Greek is not so good (as in, my Greek is practically nonexistent), so you may be right.
    – thb
    Commented Jan 23, 2016 at 16:54
  • @sumelic: I like the changes, and find nothing further to add to them. You have been generous with your time. Thanks.
    – thb
    Commented Jan 23, 2016 at 17:25

[This is an important question because of all the folks visiting this site for guidance, who may well pass answers on to other students and writers. I myself in my pre-linguist days used to fall victim to this 'rule'. I have total sympathy for the Original Poster, as I do for my former self, and all literature, EFL students and authors who are confronted with this so-called grammar rule. GMAT students don't despair, just find which non-existent rule they're looking for now. It's quite good fun and not that difficult. Anyway here's my answer to the question...]

The idea that which is not used for restrictive clauses is a myth promulgated in the worst English grammar text-books and style guides ever written. The greatest writers in the English language have continuously used which as a relative pronoun in restrictive relative clauses — as has everyone else too.

Some info from the post Sidney Goldberg on NYT grammar: zero for three, by Geoffrey Pullum, Professor of General Linguistics at the University of Edinburgh, co-author of the Cambridge Grammar of the English Language (2002), shows how far through various books you would need to go before finding which appearing as a restrictive relative pronoun. The first number given in the list below shows the number of lines in the entire book. The second number shows on which line the author first used which as a relative pronoun in a restrictive relative clause:

  • A Christmas Carol (Dickens): 1,921 lines, first occurrence on line 217 = 11% of the way through;
  • Alice in Wonderland (Carroll): 1,618 lines, line 143 = 8%;
  • Dracula (Stoker): 9,824 lines, line 8 = less than 1%;
  • Lord Jim (Conrad): 8,045 lines, line 15 = 1%;
  • Moby Dick (Melville): 10,263 lines, line 103 = 1%;
  • Wuthering Heights (Bronte): 7,599 lines, line 56 = 0.736%...

Now, I know these authors are idiots who didn't know how to speak English properly, but just how did their editors and publishers get away with it? And all the people who decided to put these books on school syllabi? They, of course, should be shot.

Getting serious again: importantly, as Pullum also shows in the post A Rule Which Will Live in Infamy, there are situations when we, in fact, cannot use that for restrictive clauses and in which we have to use which. (Oh look one of them happened right there. I couldn't for example have written ... "and in that we have to use which"). Here are the three situations Geoff Pullum describes:

  • The putative ban can’t apply when a preposition precedes the relative pronoun: The town in which she lived is grammatical but *the town in that she lived isn’t.
  • The supposed rule should be ignored when modifying demonstrative that, because that which you prefer is clearly preferable to ?that that you prefer.
  • The rule can’t apply to a conjoined which: We must trust the unknown entity who or which created us is grammatical but *We must trust the unknown entity who or that created us isn’t.

Here is the passage in which (Oh no, there I go again with another one!) the famous quote that Pullum is playing with appears:

“Yesterday, December 7, 1941—a date which will live in infamy—the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan.” That was how President Franklin D. Roosevelt opened his famous infamy speech, 71 years ago. Ignoring the writing handbooks, he opened with a passive construction, which of course is just right for the rhetorical context (America as innocent victim). And he also ignored another bogeyman rule: He introduced a restrictive relative clause with which.

The answer to the OP's question, therefore, is that which can, and sometimes must, be used for restrictive relative clauses. It's not a mistake to do so.

I leave you with Geoff Pullum's last words from the link above:

Grammar snobs trying to show off their linguistic rectitude by playing gotcha with an invented rule that never matched educated usage; copy editors slaving away trying to enforce it; Microsoft Word blindly putting wavy green underlining under every relative which not preceded by a comma. What a senseless waste of time and energy.

Follow the Fowler rule if you want to; it’s up to you. But don’t tell me that it’s crucial or that the best writers respect it. It’s a time-wasting early-20th-century fetish, a bogeyman rule undeserving of the attention of intelligent grownups.

  • 1
    I appreciate the time spent to post this answer and its detail. I'm curious about the apparent annoyance about my (seeming) misconception--it was just a question! The resources you picked seem particularly vitriolic about the topic. Also, I didn't find the use of in which to be compelling or clever--clearly, in which is restrictive, but I wasn't asking about it. Also, when that is not correct, which must obviously be used. My question was not about those cases.
    – ErikE
    Commented Aug 21, 2014 at 22:48
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    @ErikE Sorry if it came across that I'm annoyed about your question. I'm not!! Really, really not! I think it's a very, very important question indeed, and I don't for one sec think there's anything wrong with having this idea per se. What does kind of make me mad though is that someone invented this rule, and it now affects language learners, writers, students, grammarians and GMAT sitters all over the globe, when the so-called grammar point never had any basis in the actual language! I don't understand what GMAT want people to use when they want need to say the box in which its hidden ... Commented Aug 21, 2014 at 23:15
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    I think saying "Which cannot be used in any restrictive sense" is patently false. It can be used, but with different constructions such as in which or that which. As a drop-in replacement for that (when used in its restrictive sense), it seems less apt to me.
    – ErikE
    Commented Aug 22, 2014 at 0:04
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    @ErikE: the difference between restrictive which and non-restrictive which in speech is conveyed by intonation, stress, and whether there is a short pause before which. The difference in writing is conveyed by context and/or by a comma before a non-restrictive which. There's no need to restrict which to non-restrictive clauses, and this is a very confusing rule because it goes against the natural tendencies of several hundred million native English speakers, most of whom wouldn't be able to tell you what a non-restrictive clause was, even though they know intuitively. Commented Aug 22, 2014 at 14:24
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    You should repost this answer on the much older and much upvoted page english.stackexchange.com/questions/78/… but then you've got to explain why you posted this comment -1 The most useful information here would surely be that that *CAN'T be used in non-defining clauses!!!
    – Mari-Lou A
    Commented Jun 20, 2018 at 19:06

In British English usage the two are largely interchangeable, with the restrictive/non-restrictive distinction being indicated only by the presence or absence of a comma preceding the pronoun in question. This more often manifests itself as a restrictive "which" rather than a non-restrictive "that".

The only dissent that one may encounter in the UK tends to be a result of over-familiarity with the Americanish preferences of the Microsoft Word grammar checker, especially in earlier versions.


I have always learned - and therefore taught - that the choice to use "that" or "which" in a restrictive/identifying clause is purely based on register. "That" is used in an informal or spoken setting, whereas "which" is preferably used in more formal situations, for example in a formal report or essay.

"That" and "which" are therefore interchangeable in a restrictive clause, in my book.

Similarly, we can use "that" to refer to a person in informal, spoken register. Here below are examples which are all grammatically correct but go from least to most formal. The last two are probably outdated today.

The guy that I spoke to yesterday was French.

The guy who I spoke to yesterday was French.

The gentleman whom I spoke to yesterday was French.

The gentleman to whom I spoke yesterday was French.

As for usage in non-restrictive clauses, you can only use "which" with commas to mark the non-essential relative clause.

  • Register is probably part of it. However, I don't think there's a clear-cut gradient in usage based on register; obviously people who believe restrictive "which" is "grammatically incorrect" will not use it even in formal situations.
    – herisson
    Commented Jan 23, 2016 at 16:45

The so-called American preference for banning "which" from restrictive relative clauses represents nothing more than the penetration of the educational system by Strunk and White's Elements of Style, which essentially invented the distinction where none could be demonstrated by even the most rudimentary statistical analysis.


  • You're saying that the influence was unwarranted. Nevertheless, influence it has been. Commented Jan 16, 2020 at 16:11

At times it seems rather confusing about the appropriate usage of which and that (both are used for groups and/or things and never for person*s*, at least i cant think of any such situation).

I have a simple rule to use them,

'That' implements a Restrictive/Essential clause and 'which' implements a Non-restrictive/Non-essential clause.

In your example, the 1st sentence gives an idea that the particular class of motorcycles are already identified, hence, which begins a non-essential clause.

  • 4
    There's just one problem with your rule: native speakers don't actually use 'that' and 'which' in this way...! Commented May 23, 2012 at 8:30
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    @Downvoters: Do you mind leaving a comment for voting down?!! I don't mind receiving down-votes when my answer is not good enough, it will let the readers get a better information about a subject. That's the reason I wouldn't delete an answer even if it has negative votes.
    – Fr0zenFyr
    Commented Feb 4, 2014 at 5:31
  • Reason for downvote (I suspect): Your answer was a duplicate of two previous answers and doesn't actually add anything new. Commented Apr 10, 2014 at 19:55
  • @PeterShor: I originally answered to this question which was later merged here. I doubt your reason for down-vote, i got a down-vote before it was merged. Thanks for taking time to read my comment.
    – Fr0zenFyr
    Commented Apr 14, 2014 at 9:33

The literary examples that (not which) Pullum gives are from the 19th century. The farther you go back in American history, the more closely American literary language adheres to British usage, and British usage favors the use of which over that in the case in question.


There is a difference between that and which:

  • which may be used grammatically to mark a nonrestrictive relative clause, and
  • that may not.

In restrictive clauses, of course, both are grammatical.

                                                                                                                                   John Lawler

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