When to use a coma: before or after "but"?

By Strategically AI. Reviewed by Rebecca Hey.
Updated February 18, 2023
8 minute read
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Using commas with "but" can be quite a conundrum. Even seasoned writers can get tripped up by this tricky punctuation rule. But surprisingly, the rules are pretty simple, and we are here to explain everything to clear up your confusion. 

You must figure out whether you deal with independent or dependent clauses. Independent clauses are sentences that can stand independently. In contrast, dependent clauses need help (of a main clause or independent clause) to make sense. Got it? Good.

When you've two independent clauses in a sentence, use a comma before that "but." And when the word "but" needs an interrupter word to stand, place a comma after it.

If you still find it hard to wrap your head around these rules, don't fret. We'll explain everything with plenty of examples so you can see this comma rule in action. 

When to use 'but' in a sentence?

The word "but" is one of the seven coordinating conjunctions. You can connect two independent clauses by using "but" after a comma or period.

But there are some specific conditions for starting the sentence with "but." Suppose two successive sentences present contrasting ideas, or the concept in the second sentence goes against the first sentence. In that case, you can start the second one with "but."

For example:

  • There's a DJ party on Sunday. But my best friend wants to go to a movie, so I'm going with her. 

In addition, you can also present both contrasting thoughts in a single sentence by using this coordinating conjunction to connect the clauses. 

For example:

  • This color suits you, but I don't like this outfit.
  • The food looks delicious, but I'm not hungry. 

But why is there a comma before "but" when connecting two independent clauses? We'll discuss this in the following section.

Why do you put a comma before 'but'?

The simple comma rule is to use a comma before "but" when two independent clauses are related, not sequential. It means a comma before this conjunction should be placed when connecting two thoughts that can function as standalone sentences.

Grammar rules

In educational or white paper writing, you must follow proper punctuation rules to make the writing error-free. It's pretty common to use unnecessary commas because it's one of the most used punctuation marks in English. 

You must use a comma before conjunctions like "but" or "yet" to prevent confusion and highlight the contrast between two clauses.

In addition, using a comma before conjunctions can join two independent clauses. If both clauses can stand alone, you can use a comma before "but." However, using a comma will be incorrect when a sentence has two verbs or objects with one subject. 

  • He thought the movie was great but his friend disagreed. (Incorrect)
  • He thought the movie was great, but his friend disagreed. (Correct)
  • Billy had the skills, but lacked confidence. (Incorrect)
  • Billy had the skills but lacked confidence. (Correct)

Avoid comma splice

Generally, a comma splice refers to misplaced commas in a sentence. We use a comma to divide two independent clauses using a coordinating conjunction. Don't use a comma before the conjunction if the two clauses are joined using a semicolon, period, or colon.

Also, this phenomenon can occur when you connect two independent clauses by a comma but do not use conjunction. 

For example: 

  • Mike was tired, he took a nap. (Incorrect)
  • Mike was tired, so he took a nap. (Correct)
  • Emma loves ice cream, she often catches a cold. (Incorrect)
  • Emma loves ice cream, but she often catches a cold. (Correct)

When do you need a comma before 'but'?

Depending on the sentence structure, you may sometimes need to use a comma before "but." Here is the rule of comma usage:

Generally, standalone sentences are independent clauses. 

For example:

  • I want to buy a cake.
  • The cake shop is closed.

These simple example sentences contain a subject, verb, and object. You don't necessarily need to use any added phrases to make the sentence a complete sentence.

However, the second example doesn't contain an object and is still an independent clause. Now if you want to join these two independent clauses into one sentence, you need to use a conjunction to build a link by placing a necessary comma before it. 

For example:

  • I want to buy a cake, but the cake shop is closed.

Common issues of using commas before 'but'

Some people make the mistake of placing a comma before "but" when they connect a dependent clause with an independent one. Generally, the simple rule is you don't need a comma in this situation.

Again, following different style guides is also an issue. Some style guides suggest using a comma, while others don't. 

For example:

  • Mark baked a cake but did not put in any sugar.

Some may use a comma before "but" in this above example. However, this will be a mistake because the part after "but" is a dependent clause that cannot form a meaningful sentence. 

Do you put a comma after "but"?

We all know that a comma before "but" is necessary when connecting two independent clauses. But did you know there's one situation where a comma after "but" is allowed?

If you're using an interrupter, a phrase that qualifies or emphasizes the following statement, using a comma after "but" is acceptable. Remember, though, that you'll need to add another comma after the interrupter.

  • Amelia had prepared her presentation well, but, as usual, she was still nervous.

In this example, the word "but, as usual," dramatically draws attention to the last clause. And this is the motive behind using commas after "but."

When do you need a comma after "but"?

A sentence that begins with "but" after a period doesn't need a comma after "but." However, there are still comma rules that you have to follow.

Generally, when professional content writers want to create emphasis or present the sentence as a literary device, they use a comma. The two sentences need an interrupter in the middle with an extra word or phrase. 

For example:

  • Tina's so-called friend accused her of stealing a stamp book. But, as we all know the truth, Tina was at the library when her friend lost it.

In this example, the clause "as we all know the truth" after "but" breaks the sentence flow. The punctuation after the word "but" emphasizes and draws attention to the concluding clause. And this is the primary purpose of using a comma after "but." 

Here are a few more examples:

  • The topic is exciting but, in reality, fails to capture the mass attention. 
  • My friends and I are planning a trip to the Maldives. But, who knows, we may go on a trip to Sweden instead.

In short, the ultimate goal of placing commas after "but" is to emphasize the situation using an interrupter.

When to use no comma before or after "but"

There are some simple rules for using commas before and after "but." However, you don't need to use a comma in one situation—before a dependent clause.

A dependent clause is a group of words containing a subject and a verb but does not express a complete thought. In other words, it relies on an independent clause to make sense.

These clauses are usually introduced by subordinating conjunctions such as "although," "since," "because," "while," and "if" when used at the beginning of a sentence. 

  • Although I love pizza, I can't eat it every day.

In this sentence, "although I love pizza" is the dependent clause because it has a subject (I) and a verb (love), but it doesn't express a complete thought. You get the full idea only after combining it with the independent clause, "I can't eat it every day."

However, they will be preceded by coordinating conjunctions, such as "but," "so," "and," or "yet," otherwise.

  • Ava wants to go to the Bieber concert but does not have the money. 

If you break the sentence, you will get two separate clauses:

  1. Ava wants to go to the Bieber concert.
  2. Does not have the money.

You can see that the second clause does not express a complete thought because of latching the "subject." So, this dependent clause needs an independent clause, "Ava wants to go to the Bieber concert," to be meaningful. And the coordinating conjunction, which is "but," in this case, connects the two clauses. 

In this case, using a comma before or after "but" is unnecessary to make the sentence flow seamlessly. In short, you don't need to use a comma when you connect independent clauses with dependent clauses.

Comma before or after "but": quick tips to remember 

The simplest way to determine whether you need a comma is to check the first and last sentences.

However, if the above elaborate discussion is a little tricky to remember, you can follow these quick tips.

  • If the sentence contains connecting clauses that CAN express the context, use a comma before the word "but."
  • If the word "but" joins hands with an interrupter phrase or word, you must place a comma after "but." 
  • If the first clause of the sentence is connected with a second clause that CAN'T highlight the context on its own, there is no need to put a comma before "but."

Conclusion

So, there are only three simple rules to master the correct use of putting a comma before or after "but." However, to apply these rules correctly, you must know the differences between independent and dependent clauses. 

Struggling with confusing grammar rules? No worries, we've all been there. Follow our blog to get more tips on conquering pesky commas, tricky conjunctions, and more.

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Rebecca Hey
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