Comma Before or After But | Rules & Examples

You must put a comma before “but” when it connects two independent clauses. An independent clause can function as a standalone sentence (i.e., it has a subject and a verb).

Example: Comma before “but” connecting two independent clauses
Maria hoped to go for a walk, but it rained all day.

You must use a comma after “but” only when you include an interrupter. An interrupter is a word or phrase used to emphasize or qualify the statement and to express mood or tone.

Example: Comma after “but” when using an interrupter
But, of course, Natia knew that more guests would arrive.
Note
The same rules apply to using commas with the other major coordinating conjunctions: commas before and after “and”, and commas before and after “or.”

Comma before “but” connecting independent clauses

You should include a comma before “but” when the two clauses it connects each have their own subject and verb.

This is the case even when the second subject is a pronoun referring to the same person or thing as the first clause, or when the second clause repeats the verb from the first clause.

Examples: Comma before “but” connecting independent clauses
Clint looked at me, but he didn’t speak.

They spent hours on the fishing boat, but they didn’t catch anything.

It’s sunny, but it’s not warm outside.

To simplify these sentences, you can often just omit the second subject. This way, the second clause is no longer independent, and no comma is needed.

Examples: Simplified phrasings with no comma required
Clint looked at me but didn’t speak.

They spent hours on the fishing boat but didn’t catch anything.

It’s sunny but not warm outside.

When do you need a comma after “but”?

The only time when a comma should appear after “but” is when it’s followed by an interrupter, a phrase added for emphasis or to qualify the statement. A comma appears before and after the interrupter.

Examples: Comma after “but”
Karen nodded, but, unsurprisingly, she wasn’t paying attention.

The cat is independent but, on some occasions, affectionate.

Even if a sentence begins with an introductory “but,” there’s no need for a comma unless it’s immediately followed by an interrupter.

When you don’t need a comma before “but”

While a comma is needed before “but” when it’s being used to connect two independent clauses, no comma is needed before “but” if it’s connecting an independent clause and a sentence fragment.

A sentence fragment is a clause that’s missing either a verb or a subject, or one that does not form a complete thought. For example, the clause “when Paul ran” contains both a subject and a verb, but it is an incomplete clause.

Example sentences: “But” connecting independent clauses and sentence fragments
  • The market is open not only on Saturday, but also on Sunday.
  • The market is open not only on Saturday but also on Sunday.
  • Tom likes cake, but not pie.
  • Tom likes cake but not pie.
  • The sky is not green, but blue.
  • The sky is not green but blue.

Worksheet: Comma before or after but

Do you want to test your knowledge about when to use a comma before or after but? Use our practice worksheet below. Just insert commas into the sentences wherever you think they’re needed, and then check your work against the answers provided.

  1. The lights are on but no one is home.
  2. Adam tried his best but ultimately failed.
  3. I know how to dance but as you can see I’ve broken my leg.
  4. Carey wanted the promotion but of course didn’t get it.
  5. Seth wants to go on holiday. But he doesn’t know where he wants to go.
  1. The lights are on, but no one is home.
    • The “but” here connects two independent clauses, so a comma is needed before it.
  1. Adam tried his best but ultimately failed.
    • Here, no comma is needed before “but,” as the second clause is not independent.
  1. I know how to dance, but, as you can see, I’ve broken my leg.
    • A comma appears after “but” here because it’s followed by the interrupter “as you can see.” A comma also appears before “but” because it’s connecting two independent clauses.
  1. Carey wanted the promotion but, of course, didn’t get it.
    • A comma appears after “but” here, again because it’s followed by an interrupter (“of course”). There’s no comma before “but” because it’s connecting two verbs with the same subject (“Carey”), not two independent clauses.
  1. Seth wants to go on holiday. But he doesn’t know where he wants to go.
    • An introductory “but” is never followed by a comma unless an interrupter comes right after it. Therefore, no commas are needed in this sentence.
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Eoghan Ryan

Eoghan has a lot of experience with theses and dissertations at bachelor's, MA, and PhD level. He has taught university English courses, helping students to improve their research and writing.

1 comment

Eoghan Ryan
Eoghan Ryan (Scribbr Team)
July 25, 2022 at 3:18 PM

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