When to use Which or That: the most common cases

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    When to Use Which or That: The Most Common Cases

    When do you use which or that? People use these two words every day when composing sentences. But everything isn’t as simple as it seems at first sight. In modern English, “that” and “which” are considered practically interchangeable. And it makes understanding the difference between them even harder.

    In fact, incorrect use of which or that is one of the most common grammar mistakes. You could learn English for years and still doubt when to use each word. If you want to finally understand when to use which or that in a sentence, learn the difference between restrictive and nonrestrictive clauses.

    Restrictive & nonrestrictive relative clauses

    There are two types of the relative clause ‒ restrictive and nonrestrictive. Let’s have a closer look at each of them:

    • A restrictive clause (also called a “defining/essential clause”) is a part of a sentence that limits the meaning of the noun it modifies. If a restrictive clause is not included, the meaning of a sentence will change.
    • A nonrestrictive clause (also known as a “non-defining/nonessential clause”) provides additional information about the noun and can be removed from the sentence without changing its meaning.

    Of course, with only these definitions it is hard to know when to use which or that. Follow our detailed explanations and examples to tackle this topic.

    The difference between that and which

    That is used for a restrictive clause

    A restrictive clause contains necessary information about the noun that comes before it. It identifies or limits the preceding word. Thus, you can’t remove the restrictive clause from a sentence without changing the sentence’s meaning. For example:

    Baby food products that contain soybeans are the best ones.

    Note that there should be no commas before and after the clause.

    As you can see, this sentence contains a restrictive clause “that contain soybeans”, and you understand that there are many different kinds of baby food. In case you remove it from the sentence, you will change its meaning, Baby food products are the best ones. Thus, “that clause” adds a sort of specification which influences the whole sentence.

    “Which” is used for a nonrestrictive clause

    On the other hand, a nonrestrictive relative clause describes a noun providing additional insignificant details. Just compare the following example with the previous one:

    Soybean baby food products, which are Tom’s favourite, are the best for his diet.

    Note that commas separate a nonrestrictive clause.

    Can you see the difference when to use which or that? Like a restrictive clause, a nonrestrictive clause adds extra details to the sentence. But it’s not vitally important to include it. This part of the sentence could be easily removed without affecting the meaning or structure of a sentence: “Soybean baby food products are the best for his diet”.

    When to use which or that in examples

    Using which instead of that or vice versa can change the meaning of your words. Let’s consider the following examples:

    • Our office that has three meeting rooms is located in New York.

    We have several offices, but the office with three meeting rooms is located in New York.

    • Our office, which has three meeting rooms, is located in New York.
    • We have only one office, and it’s located in New York.
    • Can I get the pen that I gave you this morning?
    • Cheesecake, which is my favourite treat, goes well with strawberry jam.
    • The luggage that is over 25 pounds will not be permitted.
    • My bedroom, which is on the third floor, is very light.

    What about exceptions?

    You’ve already found out that a restrictive clause is usually introduced by that. However, in British English, the word that can be substituted by which without any effect on the meaning.

    • Who ate the chocolates that I bought yesterday?
    • Who ate the chocolates which I bought yesterday?

    The first example is the correct one. But many people also do not consider the second sentence wrong. In British English, you can use which or that for the restrictive clause, and it won’t change the meaning, especially in informal contexts. But note that in American English, which is used only for the nonrestrictive clause.

    We recommend following the American rules to be on the safe side. It also makes it easier to decide whether to put commas or not, since, by the American rules, commas should precede which, but they shouldn’t come before that. As simple as ABC.

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