It can be tricky to work out when the word “but” needs a comma before or after it. Even professional copywriters get this wrong sometimes. But it doesn’t have to be difficult. Once you’ve learned a few simple rules, this grammatical stumbling block becomes much easier to understand.
When Do You Need a Comma Before But?
Short answer: sometimes, but not always. The way to work this out is to look at the two parts of the sentence this punctuation mark is separating. The basic rule is this: you should put a comma before “but” only when it is connecting two independent clauses.
Independent clauses are parts of a sentence that could function as complete sentences of their own. In other words, they have a subject and an object. For example:
I want to buy a new car, but I don’t have any money.
In this sentence, each clause either side of “but”—“I want to buy a new car” and “I don’t have any money”—could work as a sentence on its own. This means they are independent clauses, and it is correct to use a comma before but.
Dependent clauses are the opposite of independent clauses—they would not work as standalone sentences. For example:
I would buy a new car but for the cost.
In this variation on the previous example, the clause after but is “for the cost”, which would not make sense on its own as a sentence. It’s easy to see where the term comes from: the clause is dependent on the rest of the sentence to give it context.
When the word “but” connects an independent clause to a dependent clause, you should not use a comma.
Some More Examples
Here are some more sentences which correctly use—or don’t use—commas before “but.” Think about whether the clauses are independent or dependent, and how this has informed the comma usage.
The bakery is far away but sells amazing cookies.
The bakery is far away, but it sells amazing cookies.
Julia went to the post office, but she forgot to take her shopping list.
Julia went to the post office but forgot her shopping list.
Learning punctuation rules is a tedious experience, but it improves your writing.
Learning punctuation rules is a tedious but worthwhile experience.
It’s worth noting that this same rule applies to all other coordinating conjunctions, which can be remembered using the acronym FANBOYS: For And Nor But Or Yet So.
Do You Need a Comma After But?
Most of the time, you don’t need a comma after “but”—including when you start a sentence with it. For example:
But it doesn’t have to be so difficult.
There is no need for a comma here. However, there is an exception to this…
Comma Usage With Interrupters
The only times where you do need the comma after “but” are when it is immediately followed by an extra word or phrase, like in this example:
But, of course, it doesn’t have to be so difficult.
Here, “of course” is what’s known as an interrupter—an extra subordinate clause that interrupts the flow of the main clause and so needs to be separated off using a pair of commas.
The same rule applies when “but” does not begin the sentence:
Learning grammar is important, but, of course, it doesn’t have to be difficult.
In other cases, the interrupting clause works like an adverb to add additional meaning to the main clause that follows it, and so it’s known as an introductory phrase or introductory word. Here are some more examples of these:
But, from the beginning, he was the best member of the team.
But, naturally, I forgot all the grammar rules after learning them.
3 quick tips for remembering if you need a comma before or after but
To summarize, if you’ve got a sentence using the word “but” and you’re not sure if there should be a comma before or after it, answer these three questions:
- Does the word “but” link two phrases that would work as sentences on their own? If yes, put a comma before “but.”
- Does “but” link one phrase which would work as a standalone sentence with one that does not? If yes, you do not need a comma beforehand.
- Is the word “but” followed by an interrupter word or phrase? If yes, put a comma after “but.” If no, you do not need a comma after it.
An easy way to check whether your sentence fits the first or second criteria on this list is to break it into pieces—the piece before and after “but.” Test each piece on its own. Does each one have a subject (noun or pronoun) that performs an action (verb)?
Use this test and the tips above consistently in your writing, and soon the correct way to punctuate before and after the word “but” will become intuitive to you. You’ll be one step closer to becoming a grammar professional.
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Kieron Moore is a writer, script editor and filmmaker living in Manchester, England. As part of the Eleven Writing team, his specialisms include video editing and how to correctly use an apostrophe. He can be found on Twitter at @KieronMoore, usually when he’s meant to be writing.