Comma Before or After So | Correct Use & Examples

Commas updated on  January 10, 2024 3 min read
You need a comma before the conjunction “so” when it could be replaced with “therefore” (i.e., “for that reason”).

Example: Comma before so meaning “therefore”
I was tired, so I went to bed.
I was tired. Therefore, I went to bed.

No comma is needed before “so” when it instead means “so that” (i.e., “with the result that” or “in order that”).

Example: No comma before so meaning “so that”
Tom left early so he could arrive at the office on time.
Tom left early so that he could arrive at the office on time.

When “so” is used as an adverb, pronoun, or other part of speech, commas are generally not needed (e.g., “I hope so,” “he stayed a week or so,” “there’s still so much to do”).

Note
To learn more about using commas with other coordinating conjunctions, you can read our articles on when to use commas before or after but, commas before or after and, and commas before or.

When to use a comma before so

You should put a comma before “so” when it’s used as a coordinating conjunction to connect two independent clauses. A clause is independent if it contains both a subject and a verb and expresses a complete thought. When used in this way, “so” means “therefore” or “for this reason.”

To check whether “so” is being used in this way, try substituting it with “so that” and “therefore” to see which one more closely fits your intended meaning. For instance, consider the sentence “Jane was tired, so we rescheduled.”

When “so” is replaced with “so that,” the sentence lacks coherence, seeming to suggest that Jane’s tiredness was a deliberate tactic to make us reschedule:

Jane was tired so that we rescheduled.

When “so” is replaced with “therefore,” the sentence conveys the correct meaning (albeit in a more formal style).

Jane was tired. Therefore, we rescheduled.

In this context, “so” is acting as a coordinating conjunction and a comma is needed before it.

When you don’t need a comma with so

You don’t need a comma before “so” when it’s used as a subordinating conjunction to connect an independent clause with a dependent clause (i.e., a clause that does not express a complete thought). When used in this way, “so” is a synonym for “so that.”

To check whether “so” is being used in this way, try replacing it with “therefore” and “so that” to see which one fits the intended meaning. For instance, consider the sentence “I studied hard so I could pass the test.”

When “so” is replaced with “therefore,” the sentence makes sense, but it is unlikely to reflect the original meaning.

I studied hard. Therefore, I could pass the test.

When “so” is replaced with “so that,” the sentence accurately conveys the intended meaning: that the speaker studied hard in an effort to pass.

I studied hard so that I could pass the test.

In this context, “so” is acting as a subordinating conjunction and no comma is needed before it.

Note
While “so” is commonly used in everyday speech to mean “so that,” it’s generally better to write the complete phrase “so that” in more formal contexts, like academic writing. Doing this will make your writing more coherent.

When to use a comma after so

When “so” is used as a coordinating conjunction or subordinating conjunction, there’s generally no need to put a comma after it.

This is the case even when “so” appears as a conjunction at the start of a sentence.

It was late. So, I went to bed.
It was late. So I went to bed.

When “so” is used as an interjection, a comma is optional. You can include one to express a natural pause in the sentence.

So, how are things?
So I’ll talk to you soon.

A comma should also appear after “so” when it is followed by an interrupter (i.e., a parenthetical expression that adds emphasis or qualifies a statement). In these instances, a comma should also appear after the interrupter.

Example: Comma after so
So, unfortunately, the concert has been canceled.
There’s room in the bus, so, if you like, you can join us.

Quiz: Comma before or after so

Test your knowledge about when to use a comma before or after “so” with the worksheet below. Add commas wherever you think they are needed. Some sentences do not require a comma.
Do you want to know more about commas, parts of speech, email, or other language topics? Check out some of our other language articles full of examples and quizzes.


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Eoghan Ryan

Eoghan has taught university English courses on effective research and writing. He is particularly interested in language, poetry, and storytelling.

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