It’s not the first time you felt stymied as a writer.
It happens. You’re looking at a sentence you wrote and thinking, “Do you put a comma before so?”
Is so a coordinating conjunction? Is it a subordinating conjunction? Is it an adverb?
The short answer is, “Sure. It can be any of those things.” But until you see when and how, knowing that doesn’t help much.
Once you know the rules described in this post, though, say goodbye to confusion.
You won’t miss it.
What Is The Word “So?”
The purpose and meaning of the word “so” depends on where it stands. It can take on any of the following roles:
- Coordinating conjunction
- Subordinating conjunction
- First word of a parenthetical expression
You’ll see all these uses in the rules and examples below.
You’ll see commas before “so” and commas after it.
And by the end of this post, you’ll know exactly why.
A Comma Before or After “So”? All You Need to Know
Once you read through the following rules and examples, you’ll know when to use a comma with so and when to leave it out. When in doubt, listen for the pause.
Comma After So At Beginning of Sentence
If you’re using “so” as a conjunctive adverb at the beginning of a sentence—which happens often enough in dialogue and other less formal writing—a comma comes right afterward.
- “I only have just enough in the bank to pick up some bread and eggs. So, I won’t be buying any frozen pizzas today.”
- “You’ve spent an awful lot of time talking and laughing together over the past few weeks. So, I’m guessing divorce is off the table? Or am I wrong?”
Notice in that second example how a comma goes after the “so” but not after the “Or” at the beginning of the next sentence. The reason for that is the implied pause, however brief, that often comes after the word “so.”
It’s that implied pause that often gets writers to add the comma, even if they’re not 100% sure it belongs there.
On the other hand, the “or” takes about as much auditory space as the words that follow. It doesn’t need a pause for effect. It takes the same number of beats as the syllable that comes afterward.
You’ll hear the same pause in the next examples.
Commas After So Before a Parenthetical
Whether the “so” comes at the beginning of a sentence or somewhere in the middle, you need a comma right after it if it precedes a parenthetical expression.
- “So, after you graduate, what are your plans?”
- “So, as soon as he hung up, he went upstairs to talk to her.”
- “So, before you get angry, hear me out.”
If, on the other hand, the word “so” is part of the parenthetical expression (rather than separate), the comma comes before it, as you’ll soon see.
Commas Before So
The next time someone asks you, “Do you put a comma before so,” you can tell them, “So glad you asked! And yes, you do — in one of the following two cases:
- When it’s being used as a coordinating conjunction
- When it’s part of a parenthetical expression.”
Examples with “so” as a coordinating conjunction:
- “I had no idea where I left my pants, so I didn’t wear any. I wore a dress.”
- “He left her standing at the side of the road, so that’s the last time I ask him to take her out for driving practice.”
- “They were out of butter pecan ice cream, so I went with cherry chocolate fudge.”
Examples with “so” as part of a parenthetical expression:
- “The leader of the study group, so tired she could barely keep her eyes open, announced it was time to call it a night.”
- “The dog, so cold it was visibly shivering, walked slowly toward the blanket near the woodstove and curled up against the bricks.”
So, if the comma is part of a parenthetical, the comma comes before. If “so” comes before and is separate from the parenthetical, the comma comes afterward.
Examples of before and after:
- Part of a parenthetical (comma before): “She walked out the door, so angry at what he’d said she couldn’t speak.”
- Preceding a parenthetical (comma after): “So, despite her anger, she stayed and finished the project.”
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When is a Comma Unnecessary?
You don’t need a comma before or after so in the following cases:
#1: When “so” is an adverb of degree (like “very”)
- “He’s so busy he doesn’t have time for a pet.”
- “She’s so mad at me right now, and I’m at a loss for what to say.”
#2: When “so” means “also” — as an additive adverb
- “He fell into the hole, and, five seconds later, so did she.”
- “We’re here for a reason, and so are you.”
#3: When “so” is a subordinating conjunction
- “He drew the curtain shut so as to give her more privacy.”
- “He installed a security camera so as to scare off would-be burglars.”
None of the dependant clauses after the word so could stand alone (hence the word “dependant”). This is what sets this construction apart from the use of “so” as a coordinating conjunction joining two independent clauses.
- Coordinating: “We didn’t recognize the stranger at the front door, so we didn’t open it.”
- Subordinating: “When we don’t recognize someone at the door, we keep it locked so as to stay safe while our parents are gone.”
Put aside for the moment that the second example—and both examples of “so” as a subordinating conjunction—would sound better without the “so as.”
This is one of those cases where we’ll sacrifice simplicity and elegance to make a point.
Wrapping Up The “So” Comma Rules
Here’s a final, quick look at the rules about putting a comma before or after so.
#1 — If you can replace “so” with “and so” or “therefore,” it’s a coordinating conjunction.
If a coordinating conjunction joins two independent clauses, a comma goes before the conjunction.
Here, the word “so” implies causation. The second clause follows from the first.
- Incorrect: “She forgot the eggs so we won’t be making cookies this evening.”
- Correct; ‘She forgot the eggs, so we won’t be making cookies this evening.”
- Also correct: “She forgot the eggs, and so we won’t be making cookies…. ”
- Also correct: “She forgot the eggs, therefore we won’t be making cookies…. “
#2 — If you can replace “so” with “so that,” it’s a subordinating conjunction.
A subordinating conjunction joins an independent clause with a subordinate one. No comma is necessary.
The subordinate clause depends on the independent clause. In the latter, the subject does something so that something else will happen or be true.
The subordinate clause details the result of the subject’s intentional action.
- Incorrect: “He installed a security camera, so his family would be safe.”
- Correct: “He installed a security camera so his family would be safe.”
- Also correct: “He installed a security camera so that his family would be safe.”
While it’s perfectly correct to say, “He installed a security camera. His family would be safe,” you can guess that the two are connected, but you lose the part where he installed the security camera with the express intention of keeping his family safe.
#3 — If your “so” comes at the beginning of a sentence as a conjunction, a comma goes after it.
Like it or not, starting a sentence with a conjunction has become more accepted. The Chicago Manual of Style even defends it as grammatically correct.
If you’re starting a sentence with “so,” you can hear the slight pause afterward — which you don’t typically have after a “but,” an “and,” or an “or.”
Putting a comma after the so enforces that pause. It’s just enough of a pause to warrant a comma but not enough to justify a dash, which would look pretty ridiculous there, anyway.
Let’s look at some examples:
- Incorrect: “So he’s hoping you’ll forgive him for the whole toaster debacle.”
- Correct: “So, he’s hoping you’ll forgive him…. ”
- Incorrect: “So, I was wondering if we could stop at the store.”
- Correct: “So, I was wondering if we could stop at the store.”
The exception would be a sentence that starts with a construction like, “[Just] So you know… “ or “[Just] So we’re both on the same page,” in which case, “so” is part of a parenthetical expression (with an implied “just” before it) rather than as a conjunction.
As you know, when “so” leads a parenthetical expression, a comma goes before it. But if the expression is at the beginning of the sentence, the comma has nowhere to go.
- Example → “So you know, I ate the last piece of pie.”
- Slightly different meaning → “So, you know, I ate the last piece of pie.”
#4 — If your “so” comes at the end of a quotation, a comma goes after it.
When you’re writing dialogue, if the word “so” comes at the end of a quotation, unless it’s the end of the sentence, too, you’ll need a comma after it.
- Example → “If only it were so,” he said, “but it’s not.”
- Example → “He always knew it would be so.”
Often, when “so” appears in dialogue, it’s used as a conjunction, in which case a comma would go after it even if it didn’t come at the end of a quotation.
- Incorrect: “So” I said, “You coming or what?”
- Correct: “So,” I said, “You coming or what?”
- Also correct: “So, I said, ‘You coming or what?’”
#5 — If your “so” comes at the beginning of a parenthetical expression, a comma goes before it.
If “so” is the first word of a parenthetical expression, a comma goes right before it — as it would even if so were not part of the expression. That’s just how parenthetical work.
Allow us to demonstrate with a few examples:
- Incorrect: “Also so we’re clear, no one gets to borrow my toothbrush.”
- Incorrect: “Also so we’re clear no one gets to borrow my toothbrush.”
- Correct: “Also, so we’re clear, no one gets to borrow my toothbrush.”
#6 — If your “so” comes right before a parenthetical expression, a comma goes after it.
If “so” comes right before a parenthetical expression, you need a comma to separate the two.
- Incorrect: “So before you say anything, you should know I just got here.”
- Correct: “So, before you say anything, you should know I just got here.”
- Incorrect: “So instead of cooking, I thought we’d try UberEats, just this once.”
- Correct: “So, instead of cooking, I thought we’d try UberEats…. “
Granted, with “so” at the beginning of the sentence, you’ll almost always need a comma after it, anyway.
What about sentences where “so” isn’t the first word?
- Incorrect: “He agreed to the meeting, so to be fair we should go.”
- Incorrect: “He agreed to the meeting so to be fair, we should go.”
- Incorrect: “He agreed to the meeting, so to be fair, we should go.”
- Correct: “He agreed to the meeting, so, to be fair, we should go.”
#7 — If your “so” means “very” or “also,” it’s an adverb, and you don’t need a comma.
Sometimes, “so” is just an adverb meaning “very” or “also.” And you don’t put commas before or after adverbs unless another rule comes into play.
Example: “He’s so, you know, awkward.”
In the above example, the comma comes after “so” only because it comes right before a parenthetical expression.
That’s not an issue with the following examples:
- Incorrect: “He’s so, nervous about the play, he’s locked himself in the bathroom.”
- Incorrect: “He’s, so nervous about the play…. “
- Correct: “He’s so nervous about the play…. “
Now that you’ve seen all the rules and examples regarding commas before and after “so,” which ones did you find most helpful? And what’s your biggest takeaway?