Knowing when to use a comma with conjunctions is essential for clear writing. The rules differ depending on the type of conjunction.
Comma with Coordinating Conjunctions (FANBOYS)
Use a comma before a coordinating conjunction when it joins two independent clauses (complete sentences).
- I like coffee, but I don't like tea. (two complete sentences)
- She studied hard, so she passed the exam.
Do not use a comma when joining words, phrases, or when the second part is not a complete sentence.
- I like coffee and tea. (words, no comma)
- She sang and danced. (words, no comma)
- He opened the door and walked inside. (phrases, no comma)
Comma with Subordinating Conjunctions
Use a comma after the dependent clause when it comes before the independent clause.
- Although it was raining, we went for a walk.
- Because I was tired, I went to bed early.
- If you study hard, you will pass.
Do not use a comma when the dependent clause comes after the independent clause.
- We went for a walk although it was raining.
- I went to bed early because I was tired.
- You will pass if you study hard.
Comma with Correlative Conjunctions
Generally, do not use a comma with correlative conjunctions (either/or, neither/nor, both/and).
- Either you come or you stay.
- She is both smart and kind.
However, with "not only...but also," a comma is often used before "but also" when it connects clauses.
- Not only did she win the race, but she also broke the record.
The Oxford Comma with "And" and "Or"
The Oxford comma is the comma before "and" or "or" in a list of three or more items.
Without Oxford comma: I love my parents, Lady Gaga and God. (ambiguous) With Oxford comma: I love my parents, Lady Gaga, and God. (clear)
Use it or don't — but be consistent.
Common Comma Errors
| Incorrect | Correct | Explanation | | ------------------------------------------ | ---------------------------------- | --------------- | | I like coffee , and tea. | I like coffee and tea. | Not two clauses | | Although he tried , but he failed. | Although he tried, he failed. | Remove "but" | | I was tired , because I worked late. | I was tired because I worked late. | Clause after |