You must put a comma before ‘but’ when it connects two independent clauses. An independent clause can function as a standalone sentence (i.e., it has a subject and a verb).
Example: Comma before ‘but’ connecting two independent clausesMariahoped to go for a walk, but itrained all day.
You must use a comma after ‘but’ only when you include an interrupter. An interrupter is a word or phrase used to emphasise or qualify the statement and to express mood or tone.
Example: Comma after ‘but’ when using an interrupterBut, of course, Natia knew that more guests would arrive.NoteThe same rules apply to using commas with the other major coordinating conjunctions: commas before and after ‘and’, and commas before and after ‘or’.
A comma splice is a grammatical error that occurs when a comma is used to join two independent clauses without a conjunction. An independent clause can function as a standalone sentence, because it has its own subject and verb.
To fix a comma splice, you can:
Replace the comma with a semicolon (;) to show that the two parts of the sentence are closely related
Replace the comma with a full stop (.) to create two separate sentences
Add a coordinating or subordinating conjunction (e.g., ‘and’, ‘although’) to indicate the relationship between the clauses or to emphasise one of them
Sentence with comma splice
Revised sentence(s)
Rose likes fruit, she doesn’t like vegetables.
Rose like fruit; she doesn’t like vegetables.
Eli is a volunteer firefighter, Ben is an event planner.
Eli is a volunteer firefighter. Ben is an event planner.
In English, you must put a comma before ‘and’ when it connects two independent clauses. A clause is independent when it could stand on its own as a sentence–it has its own subject and verb.
Example: Comma before ‘and’ connecting two independent clausesJagmeetwalks to school, and Rebeccatakes the bus.
But when ‘and’ connects two verbs with the same subject, you shouldn’t use a comma.
Example: ‘And’ connecting two verbs with the same subjectJagmeetwalks to school and arrives early.
In this case, Jagmeet is the subject who performs both actions (walking and arriving).
NoteThe same rules apply to using commas with the other main coordinating conjunctions: commas before or after ‘but’, and commas before or after ‘or’.