Comma Before or After But: Rules and Examples Explained

Few punctuation marks confuse students quite like “but.” Does the comma go before or after but? Students mess this up every day and can turn otherwise good writing into carelessness. Here’s the rule of thumb. When “but” connects two complete sentences, you should put a comma before it. You almost never need a comma after “but,” unless there is an interrupter (a removable phrase) after it.

In this article, we will show you both rules with examples. We will discuss putting a comma before or after but, when it is optional, and what to avoid.

Comma Before "But"

The most common reason for using comma before but is when it’s a coordinating conjunction. A conjunction is any word that joins two elements of equal importance. When “but” links two independent clauses (i.e., two sets of words that could each form a complete sentence), you should put a comma before it.

Here’s a quick test. Look at everything after the “but”. Can you imagine it starting the sentence? If yes, you probably need a comma. 

• Correct: She studied all night, but she still felt nervous about the exam.
• Incorrect: She studied all night but she still felt nervous about the exam.

In that sentence, “she still felt nervous about the exam” would be just fine all by itself. Therefore, you need the comma before but. 

Now for the reverse: If but isn’t joining two complete sentences, you most likely want to omit the comma. This will be the case most often when the two parts of the sentence have the same subject, and but merely connect the two verbs or verb phrases.

• Correct: He is tired but happy. 
• Incorrect: He is tired, but happy. 

Here, “happy” would not be a complete sentence by itself. Therefore, you don’t need the comma. 

Consider this pair:

• I called him, but he didn’t answer. (Two complete sentences, so precede but with a comma.)
• I called him but got no answer. (The second clause doesn’t have a subject by itself, so no comma.) Whenever in doubt, cover up the part before but and read the part that remains. If it sounds like a complete sentence, insert the comma.

Pro Tip: Consider replacing "but" with a period. If you are left with two complete sentences ("She studied all night. She still felt nervous. "), then you should use the comma. If the second sentence dwindles into a fragment ("He is tired. Happy. "), then you don't need it.

Writers studying language and meaning may also find these double entendre examples useful for understanding wordplay and interpretation.

Comma After "But"

Under most circumstances, do not insert a comma after but immediately. The word serves as a connector to the clause that follows it, and using comma after but only gets in the way.

• Correct: “I was nervous but I finished the speech anyway.”
• Incorrect: “I was nervous, but, I finished the speech anyway.”

There is one exception. You can place a comma after “but” if you are offsetting an interrupter. An interrupter is a phrase that you can remove from the sentence without rendering the sentence grammatically incorrect. In these instances, the comma will come in pairs. One will be placed after but, and the second will appear after the phrase.

• Correct: “She apologized but, to be fair, the mistake wasn’t entirely hers.”
• Correct: “But, honestly, I never expected to win.” 
• Correct: “We can leave now but, if you prefer, we can wait a little longer.”

Notice that in each of these examples, the interrupter (“to be fair,” honestly,” “if you prefer”) can be removed from the sentence and the sentence will still make sense. This is how you know the commas are in the correct spot.

If there is no interrupter, then the comma should not appear.

• Correct: “But of course you already knew that.” 
• Incorrect: “But, of course you already knew that.” (There should be a second comma after “course” to close off the phrase.)

Pro Tip: A comma following but almost never travels alone. If you find yourself writing one, double check to make sure that there is another comma that closes off the phrase. If you can’t find a place to put the second comma, the first one doesn’t belong.

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"But" at the Beginning of a Sentence

You’ve probably heard about never starting a sentence with but. That’s simply not true. It’s perfectly fine to do so. In fact, good writers do it frequently to add emphasis or signal a shift in thought. The rules about commas don’t change just because “but” gets moved to the front.

The baseline is still no comma. If you have “but” introducing your main clause directly, you want that sentence to run on without pause.

• Correct: “But I wasn’t ready to give up.”
• Incorrect: “But, I wasn't ready to give up.” 

You only want to add a comma if you have something interrupting the thought after “but”. Just like before, that comma needs to come in pairs to close off the interrupting phrase.

• Correct: “But, to be honest, the plan never made sense.”
• Correct: ‘But, knowing her, she’ll arrive early anyway.” 
• Incorrect: “But, the plan never made sense.”

The example sentence has no interrupter, and thus that comma is not needed.

• “But everyone deserves a second chance.” (no comma because we’re getting right to the thought)
• “But, in my experience, second chances are rare.” (The interrupting phrase “in my experience” gets two commas to close it off)

Pro Tip: Using comma when starting a sentence with but is great for adding emphasis in informal and persuasive pieces. But try not to overdo it in formal papers.

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When You Need No Comma at All

Not all instances of “but” require using comma before them. In fact, most simple sentences require none. Omit the comma whenever what comes after “but” would not form a complete sentence on its own. To be complete, it must have its own subject and verb.

This will be true any time you’re joining two fragments with “but,” or if you’re connecting an independent clause with a dependent one.

Do not add a comma: 

• Before or after “but” when joining fragments: “I like coffee but hate tea.” (The fragment after “but” has no subject.)
• When both verbs share the same subject: “He wanted to go but couldn’t afford the ticket.”
• When writing short contrasts: “She smiled but said nothing.” 
• Right after “but” if there’s no interrupter: “But she never replied.”

Consider the following examples which do require commas. Watch for the difference: 

• Immediately before “but” when there are two complete clauses: “She loves the beach, but he prefers the mountains.”
• On both sides of “but” when there’s an interrupter: “She is tough, but, of course, she has a soft side.”

See the similarity? Each of the first examples above (“hate tea,” “said nothing,” etc.) would fail if you tried to turn them into their own sentences. The second set (“he prefers the mountains”) would not. That tiny difference is what determines whether you need a comma.

Pro Tip: If the sentence reads short and sweet, with no natural pauses, you probably don’t need to use a comma. Hold onto your commas for when two complete thoughts come together, or when you want to use an interrupter.

Grammar questions often go beyond commas. For example, many students confuse mater or masters when referring to academic degrees.

Wrapping It Up

Deciding where to place a comma with the word but can be simplified with this question: can both sides of but stand alone? If the answer is yes, put a comma before but. If the answer is no, then don't. The only time you should ever place a comma after but is when you have an interrupter between but and the rest of the sentence. Learn this, and you'll never worry about punctuation again.

For broader grammar guidance, see our guide on how to use punctuation marks

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