How to Use (and Avoid) the Phrase “of which” in a Sentence

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Some people would like you to think that the rules of English grammar are set in stone.

They want you to follow the rules, and pretend that grammar has always been the way they say it is.

You might even hear them say that you’re speaking incorrectly, even if you’ve been saying something a certain way all your life.

While these people are certainly overstating their case, there is something to be said for knowing what the rules are.

One of the most commonly maligned (and most commonly broken) grammar rule is that you are never supposed to end a sentence with a preposition.

As an example, consider the phrase “of which.”
 

How do you use “of which” in a sentence?

The phrase “of which” is a prepositional phrase used at the beginning of a relative clause, a type of clause used to identify the noun before the preposition. Specifically, “of” is the preposition, while “which” is the relative pronoun. To use this phrase in sentence, simply place a comma after a noun you wish to explain in more detail and then add the explanation, preceded by “of which.”

 

What is “of which”?

“Of which” is a prepositional phrase, meaning it is made up of a preposition, “of,” and one other word. In this case, that other word is “which,” a pronoun used to provide more detail about a person, place, thing or idea referred to elsewhere in the sentence.

Taken together, the meaning is something like “regarding the [noun] previously mentioned, some additional details include…”

Because that’s very wordy, it’s much easier to just say “of which.”

 

How to use “of which” in a sentence

The phrase “of which” can only appear at the beginning of a relative clause, a special type of clause that is used to further explain another part of the sentence in which it appears.

When using “of which” to begin a relative clause, first you must place a comma after the noun. Next, add “of which.” Finally, write the rest of the clause to better explain the noun.

Relative clauses can be inserted at the end of a sentence, in which case they are followed by a period, or they can fall in the middle of a sentence, in which case they need to be followed by another comma.

The formulas, then, are as follows:

[start of sentence] [noun], of which [relative clause]. [start of sentence] [noun], of which [relative clause], [rest of sentence]

Examples

It should be clear from these examples how “of which” is used in several different contexts.

As the first two show, the phrase is often used to begin a relative clause involving numbers. However, that doesn’t have to be the case.

 

Other ways to write “of which”

If you don’t want to figure out how to use “of which” in a sentence, try one of these alternatives.

 

 

Replacing “of which” with “which … of”

Technically speaking, you shouldn’t end a sentence with a preposition in formal writing. This is the reason for the somewhat confusing phrase, “of which.”

Today, this rule is fairly relaxed, and in more casual writing, or everyday speech, you will be more likely see the relative clause started with just “which,” and the word “of” fall either at the end or elsewhere in the clause, instead.

Examples

In the last two examples here, “of” appears at the end of the relative clause, placing it at the end of the second sentence altogether.

The first example is a little more complicated to rewrite, but what appears above is grammatically correct all the same.

 

Replacing “of which” with a separate sentence.

Another way to avoid guessing how to use “of which” in a sentence is to simply split the relative clause into its own sentence.

However, this technique can look awkward, especially if overused.

Examples

Note that the last example requires us to split the relative clause out from the middle of the main sentence, and requires additional rewriting as well to be clear what the “which” referred to.