When to Put a Comma Before or After “But”| Grammarly Blog

Deciding whether to put a comma before or after but in a sentence is hard for a lot of writers, but it doesn’t have to be for you!

When to put a comma before or after but

Before we get into the details, here’s a quick overview of when to use a comma before or after but:

Before but: when but is used as a coordinating conjunction to connect independent clauses
After but: when but is used as an interrupter, usually at the beginning of a sentence
No comma with but: when but is used to connect phrases but not independent clauses

When do you need a comma before but?

You should put a comma before but only when but is connecting two independent clauses.

I would go for a walk, but it’s raining outside.

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How do you know you have two independent clauses? First, look at the words before but: I would go for a walk. Then look at the words after but: it’s raining outside. Both of those phrases could stand alone as complete sentences. That means they’re independent clauses, so you need to use a comma before but.

When you don’t have two independent clauses, leave the comma out.

I would go for a walk, but for the rain.

This time, but is connecting an independent clause to a dependent clause. How do you know? Look at the words after but: for the rain. That phrase can’t stand by itself as a complete sentence, which means it’s a dependent clause. Therefore, you shouldn’t use a comma before but.

I would go for a walk but for the rain.

Examples of when you should and shouldn’t use a comma before but in a sentence

The dog is young, but well trained.

The dog is young but well trained.

Grammar is boring, but necessary.

Grammar is boring but necessary.

The dog is young but he’s well trained.

The dog is young, but he’s well trained.

Grammar is boring but it’s necessary.

Grammar is boring, but it’s necessary.

By the way, this comma rule applies to all conjunctions, including and, or, and so.

Do you need a comma after but?

If you’re wondering whether you need a comma after but, the answer is that you probably don’t.

The only time you need a comma after but is when it is immediately followed by an interrupter. An interrupter is a little word or phrase that interrupts a sentence to show emotion, tone, or emphasis. You should always use a comma before and after an interrupter.

But, of course, it’s not safe for Spot to go outside on his own.

In the sentence above, of course is an interrupter. You could take it out of the sentence without losing any meaning. The only reason it’s there is to emphasize the obviousness of the statement. If your sentence happens to place an interrupter directly after but, then go ahead and use a comma. Otherwise, you don’t need a comma after but.