Main comma rules
Most commas fall into one of these uses.
| Rule | Example |
|---|---|
| Between items in a list | We visited Jaipur, Agra and Delhi. |
| Before and, but, or, so, yet when they join two full clauses | The flat is small, but the rent is low. |
| After an opening word, phrase or clause | However, the plan failed. After the match, we ate. |
| Around extra information (non-defining clauses and phrases) | Mr Shah, our new manager, starts today. |
| When speaking to someone directly | Thank you, Priya. |
| Before or after direct speech | She said, "I'm tired." |
| Between two adjectives of the same kind | a long, tiring journey |
The Oxford comma
The Oxford comma, or serial comma, is a comma before and or or at the end of a list: "red, white, and blue". It is optional. It is a matter of style, not a grammar rule, and both forms are correct.
Many British publications leave it out; many American ones and Oxford University Press use it. Whichever you choose, be consistent, and add it whenever it prevents confusion: "I thanked my parents, Ali, and Sara" makes clear that Ali and Sara are not your parents.
Where not to put a comma
Between a subject and its verb: "The number of students who passed rose", not "The number of students who passed, rose".
Before a that clause: "He said that he was busy", not "He said, that he was busy".
Before a defining clause: "People who exercise sleep better" needs no commas, because the clause tells you which people.
Alone between two full sentences: "It rained, we stayed in" is a comma splice. Add a joining word or use a full stop.
Common mistakes
Wrong: The main problem in big cities, is traffic.
Right: The main problem in big cities is traffic.
Never separate a subject from its verb with one comma.
Wrong: She told me, that she was leaving.
Right: She told me that she was leaving.
No comma before a that clause.
Wrong: Mr Rao who is our principal retired today.
Right: Mr Rao, who is our principal, retired today.
The clause is extra information about a named person, so it needs a pair of commas.
Wrong: Unemployment fell, inflation rose.
Right: Unemployment fell, but inflation rose.
Two full sentences need a joining word after the comma, or a full stop.
Using this in IELTS and PTE
Comma errors are frequent in IELTS and PTE writing, and the costly ones are the comma splice and the comma between subject and verb. Linking words at the start of a sentence ("However," "In addition," "Overall,") take a comma after them. In PTE Summarize Written Text, commas and joining words let you build one correct sentence from several ideas.
5 questions
Exercise
Try each one, then open it to check your answer.
1. Add commas: "Before the test I revised my notes."
Before the test, I revised my notes.
A comma follows an opening phrase. With very short phrases some writers drop it, but it is never wrong.
2. Add commas: "Dubai which is in the UAE is very hot."
Dubai, which is in the UAE, is very hot.
Non-defining information about a named place goes between commas.
3. Comma or not? "I was hungry (,) so I made some soup."
Comma.
So joins two full clauses.
4. Is "apples, pears, and plums" correct?
Yes, and so is "apples, pears and plums".
The Oxford comma is optional.
5. Remove the wrong comma: "Students who work hard, usually pass."
Students who work hard usually pass.
The comma split the subject from its verb, and the defining clause needs none.
Frequently asked questions
Is the Oxford comma correct?+
Yes, and so is leaving it out. It is a style choice. Use it when it prevents confusion and be consistent.
Do I need a comma before because?+
Usually not: "We left because it was late." Add one only if the because clause is extra information or the sentence could be misread.
Do I need a comma after however?+
Yes, when it starts a sentence or follows a semicolon: "However, the cost rose." In the middle of a clause, it takes commas on both sides.
What is the difference between a comma and a semicolon?+
A comma separates parts within a sentence. A semicolon can join two complete sentences on its own; a comma can't.
Keep going
More grammar lessons
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