This comprehensive guide will clarify the comma rule for “so” and provide examples to help you use it correctly. We’ll cover the different functions of “so” in English grammar and when a comma is necessary or unnecessary.
Here’s a quick summary of when you should use commas before or after SO:
Usage of "So" | Comma Before | Comma After |
---|---|---|
Coordinating conjunction | Yes | No |
Subordinating conjunction | No | No |
Introductory clause | No | Yes |
Parenthetical expression | No | Yes |
Emphasis/Interjection | No | Yes |
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Contents
What Is The Function Of “So” In English Grammar?
The word “so” can serve as a coordinating conjunction, subordinate conjunction, and adverb.
1. As Coordinating Conjunction
One of the primary functions of “so” is as a coordinating conjunction, which means it connects two independent clauses, complete thoughts that can stand alone.
For example, in the sentence, “I was tired, so I went to bed early,” the word “so” links two ideas: being tired and going to bed.
In this case, you need a comma before “so” because it connects these two independent clauses. Just know that whenever you see “so” joining two complete thoughts, use a comma.
2. As a Subordinating Conjunction
“So” can also act as a subordinating conjunction. It introduces a dependent clause, which cannot stand alone as a complete thought.
Let’s consider the sentence, “She studied hard so she could pass the exam.” “so” introduces the reason for studying hard here.
Since this is not linking two complete thoughts but rather connecting a dependent clause to the main idea, you do not need a comma before “so.” Recognizing when “so” serves this role will help you avoid common punctuation mistakes.
3. As An Adverb
Additionally, “so” can function as an adverb, indicating degree or extent. In the sentence, “It was so hot that we stayed indoors,” “so” emphasizes how hot it was. In this context, there is no need for a comma either.
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When Should I Use A Comma Before “So”?
The most common reason to use a comma before “so” is when it connects two independent clauses. An independent clause is a complete thought that can stand alone as a sentence.
For example, in the sentence, “I wanted to go for a walk, so I grabbed my jacket,” both parts can be understood on their own.
Since “so” links these two ideas, you need a comma before it. Another helpful tip is to check if you can replace “so” with the word “therefore.”
If the sentence still makes sense with this substitution, then you should include a comma before “so.” In the sentence, “He was late, so he missed the bus,” you could say, “He was late; therefore, he missed the bus.”
This shows that a comma is necessary before “so.” Trust me, this technique can help you confidently determine when to use punctuation correctly.
It’s also important to be aware of common mistakes people make regarding commas before “so.” For example, consider the sentence, “I was hungry so I made dinner.” In this case, there should be a comma before “so” because it connects two independent clauses.
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When Should I Not Use A Comma Before “So”?
One situation where you should not use a comma before “so” is when it introduces a dependent clause. A dependent clause is a part of a sentence that cannot stand alone as a complete thought.
Let’s take a look at the sentence “She was excited so she could see her friends,” the phrase “so she could see her friends” depends on the first part of the sentence and does not need a comma.
“So” here connects a dependent clause to the main idea, you should skip the comma. Another situation where you don’t need a comma before “so” is when it functions as an adverb.
In this case, “so” indicates degree or extent rather than connecting two clauses. For example, “It was so cold that we stayed indoors,” you do not use a comma because “so” emphasizes how cold it was rather than linking two complete thoughts.
Similarly, in the sentence “She was so happy that she cried,” there’s no need for a comma because “so” describes the extent of her happiness.
You should also avoid using a comma when “so” connects two independent clauses without needing separation.
In this case, “I was tired so I went to bed,” there’s no comma because it directly connects two complete thoughts.
If you were to write, “I was tired, so I went to bed,” that would be correct because it separates two independent clauses with a comma.
Additionally, consider the example, “He studied hard so he could pass the exam.” There’s no comma before “so” here because it introduces the reason for studying hard and connects a dependent clause to the main clause.
Another example is, “The movie was boring so we left early.” In this case, no comma is needed because “so” directly connects two independent clauses without needing separation.
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When To Use A Comma After “So”?
There are scenarios where placing a comma after “so” is necessary. One common case is when “so” starts a new sentence.
If you write, “I was feeling tired. So, I decided to take a nap,” the comma after “so” helps to create a pause that makes the sentence easier to read.
This pause signals to your reader that you are introducing a new thought that connects back to the previous sentence.
Another example could be, “The weather was terrible. So, we stayed indoors all day.” The comma here emphasizes the reason for staying inside.
You should also use a comma after “so” when it is part of a parenthetical element. A parenthetical element is an extra information added to a sentence that can be removed without changing the main meaning.
In this scenario, “So, as you can see, we need to make some changes,” the commas around “as you can see” provide extra information without interrupting the main idea.
The comma after “so” helps clarify that what follows is an explanation of what was just stated. Another example could be, “So, in conclusion, we must act quickly.”
This structure allows you to insert additional thoughts smoothly. Additionally, using a comma after “so” can help emphasize your point.
Let’s take for instance, “So, this is why we need to hurry,” the comma adds a slight pause that draws attention to the reason being presented.
This makes your writing more engaging and helps your readers understand the relationship between your ideas. You could also say, “So, remember to bring your notes,” where the pause gives weight to what follows.
That being said, you need to avoid common mistakes with commas after “so.” Many people forget to include the comma when it is needed, which can lead to confusion.
Let’s say you write, “I was excited so I went to the concert,” it would be clearer with a comma: “I was excited, so I went to the concert.”