Comma Before Because | Rules & Examples

You normally shouldn’t use a comma before “because” when the reason that “because” introduces is essential to your meaning. For example, the point of the sentence below is to give a reason for good grammar’s importance.

Examples: “Because” introducing essential clause
Good grammar is important because it allows you to express yourself clearly.

When you add a comma before “because,” it removes the emphasis from the reason it introduces. The main point of the sentence below is simply to state the importance of good grammar; the reason is an afterthought.

Examples: Comma before “because”
Good grammar is important, because it allows you to express yourself clearly.
Note
Similar rules apply to other subordinating conjunctions: commas before “while” and commas before “as well as.”

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When to use a comma before “because” in positive statements

In a positive statement (one that doesn’t include “not”), adding the comma before “because” draws the reader’s focus to what comes before it as the main point of the statement. Leaving it out makes them focus on the “because” clause.

The choice is often informed by the surrounding context. Consider the example below.

Example: “Because” introducing essential information
Colin went to bed late because he stayed up playing video games. I went to bed late because of a family emergency. It’s not the same!

The point of these sentences is to contrast the two subjects’ reasons for going to bed late. It wouldn’t make sense to add a comma to either sentence; the “because” clauses are the main point (they’re called restrictive clauses or essential clauses).

Now consider another example where the comma is added.

Example: Comma before “because” in a positive statement
Colin went to bed late, because he stayed up playing video games, but he still woke up on time.

The point of this sentence is that, despite staying up late, Colin still woke up on time. His reason for staying up late is included but not essential. It’s a nonrestrictive or nonessential clause. It could just as well be placed in parentheses, set off by em dashes, or removed.

Example: Nonessential “because” clause
Colin went to bed late (because he stayed up playing video games), but he still woke up on time.

Colin went to bed late—because he stayed up playing video games—but he still woke up on time.

Colin went to bed late but still woke up on time.

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When to use a comma before “because” in negative statements

The issue is slightly different in a negative statement (one that includes the adverb “not” or a contraction like “didn’t” or “won’t”). This is because there’s some ambiguity about whether the “because” clause represents:

  • An incorrect reason for something that did happen, or
  • A correct reason something didn’t happen

Incorrect reason

When the “because” clause indicates an incorrect reason, you should leave out the comma. Consider the example below.

Example: “Because” clause giving an incorrect reason
People don’t listen to him because he makes controversial statements. They listen because his commentary is genuinely insightful.

From these sentences, it’s clear that people do in fact listen to the person being discussed but that it’s not because of his controversial statements.

Note that the first sentence alone would be ambiguous. The context is needed to clarify whether it’s the “because” clause or the “people listen” clause that’s being negated. With sentences like this, it’s important to either provide the necessary context (as above) or rephrase:

  • People don’t listen to him because he makes controversial statements.
  • It’s not because of his controversial statements that people listen to him.

Correct reason

When the “because” clause correctly describes why something didn’t happen, you should add a comma before “because.” This lets the reader know that the “because” clause gives the reason for the negative statement. Consider the example below.

Example: Comma before “because” in a negative statement
People don’t listen to him, because he makes controversial statements.

From this sentence, it’s clear that people actually don’t listen to the person in question and that the reason for this is his controversial statements.

Unlike with the previous examples, the inclusion of the comma makes this clear from this sentence alone. There’s no possibility of misreading and no need to rephrase or add additional context in this case.

Is there ever a comma after “because”?

Normally, you shouldn’t place a comma after “because.” In most cases, there’s no reason to add one, and it’s incorrect to do so.

  • This is because, the temperature was not set correctly.

The only time when you need a comma after “because” is when it’s immediately followed by an interrupter—a phrase that interrupts the flow of the sentence to add some special qualification or emphasis. Such phrases are surrounded by commas.

Examples: Comma after “because”
This is because, as you know, the temperature was not set correctly.

Colin went to bed late because, once again, he stayed up playing video games.

When the “because” clause comes first

“Because” is a subordinating conjunction. A clause introduced by it is a subordinate clause. That means that it can’t stand on its own but must be connected with an independent clause before or after it.

The previous sections discuss how to punctuate the subordinate (“because”) clause when it comes after the independent clause. But when the “because” clause comes first, a comma should always separate it from the following independent clause.

Examples: “Because” clause at the start of a sentence
Because the weather was so nice, we decided to have a picnic in the park.

Note that it’s grammatically incorrect for a “because” clause to stand on its own as a sentence. This creates a sentence fragment.

Although sentence fragments are common in everyday speech, you should avoid them in academic writing. Always join the “because” clause to another clause before or after it:

  • We were unable to establish a causal relationship between the two variables. Because of the inherent limitations of the study design.
  • Because of the inherent limitations of the study design, we were unable to establish a causal relationship between the two variables.

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Worksheet: Comma before or after “because”

Want to test your understanding of when a comma is needed before (or after) “because”? Try completing the worksheet below. Add commas wherever you think they’re needed in the sentences given (there may be no commas needed in some cases).

  1. I’m going to be late because of traffic but please don’t start without me.
  2. I didn’t change my mind because of his arguments. I changed my mind after looking at the data myself.
  3. She didn’t vote because of her political principles. She viewed the whole system as corrupt.
  4. That’s because you never listen!
  5. This is because for all intents and purposes the issue is resolved.
  1. I’m going to be late(,) because of traffic, but please don’t start without me.
    • In this sentence, you could use a comma before “because” if the main point you’re making is just that you’ll be late. If the reason for your lateness is essential, you should omit this comma. The comma before “but” is necessary because it introduces a new independent clause.
  1. I didn’t change my mind because of his arguments. I changed my mind after looking at the data myself.
    • No commas are needed in this case. Adding a comma before “because” here would suggest that the speaker didn’t change their mind, but in fact they did—just not for the reason initially stated.
  1. She didn’t vote, because of her political principles. She viewed the whole system as corrupt.
    • It’s best to write this sentence with a comma before “because,” since without the comma it could be interpreted as meaning “she voted, but not because of her political principles.” The second sentence shows that this is not the intended meaning.
  1. That’s because you never listen!
    • There’s no need for a comma before or after “because” in this sentence.
  1. This is because, for all intents and purposes, the issue is resolved.
    • There’s a comma after “because” in this sentence to introduce the interrupter “for all intents and purposes.” Another comma appears after the interrupter.

    Other interesting language articles

    If you want to know more about commonly confused words, definitions, common mistakes, and differences between US and UK spellings, make sure to check out some of our other language articles with explanations, examples, and quizzes.

    Sources in this article

    We strongly encourage students to use sources in their work. You can cite our article (APA Style) or take a deep dive into the articles below.

    This Scribbr article

    Caulfield, J. (2023, September 11). Comma Before Because | Rules & Examples. Scribbr. Retrieved February 29, 2024, from https://www.scribbr.com/commas/comma-before-because/

    Sources

    Butterfield, J. (Ed.). (2015). Fowler’s dictionary of modern English usage (4th ed.). Oxford University Press.

    Garner, B. A. (2016). Garner’s modern English usage (4th ed.). Oxford University Press.

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    Jack Caulfield

    Jack is a Brit based in Amsterdam, with an MA in comparative literature. He writes for Scribbr about his specialist topics: grammar, linguistics, citations, and plagiarism. In his spare time, he reads a lot of books.