Comma rules: when to use a comma (with examples)

Separate three or more items: "We need flour, eggs, sugar and butter."

The comma before "and" in a list is the Oxford (serial) comma: "flour, eggs, sugar, and butter." It's optional in British English and common in American English. Use it when it prevents confusion: "I thanked my parents, Ana, and Leo" (four people? or my parents are Ana and Leo?).

Put a comma after a word, phrase or clause that comes before the main sentence:

• "However, the results were surprising."
• "After the storm, the river flooded."
• "Because the bus was late, we missed the start."

If the main clause comes first, you usually don't need a comma: "We missed the start because the bus was late."

When a conjunction (for, and, nor, but, or, yet, so) joins two clauses that could each be a sentence, put a comma before it:

"The test was hard, but most students passed."

No comma is needed if the second part isn't a full sentence: "The test was hard but fair."

Use a pair of commas around information that could be removed without changing the meaning:

"My brother, who lives in Leeds, is a nurse." (I have one brother.)

Without commas, the clause becomes essential: "My brother who lives in Leeds is a nurse" suggests I have more than one brother.

Commas also mark people being spoken to: "Thanks, Sam."

A comma splice joins two full sentences with only a comma:

✗ "It was raining, we stayed inside."

Fix it with a full stop, a semicolon, or a conjunction:

• "It was raining. We stayed inside."
• "It was raining; we stayed inside."
• "It was raining, so we stayed inside."

Examiners notice comma splices in GCSE English Language, where accurate punctuation is part of the writing marks.

• A comma between the subject and the verb: ✗ "The students in the class, were tired."
• Only one comma around extra information: "My brother, who lives in Leeds is a nurse."
• Commas wherever you'd pause when speaking: pauses and commas don't always match.

Our AI English tutor checks punctuation in your own sentences and explains each fix.

1. "I enjoy reading, my brother prefers football."
2. "However the plan was too expensive."
3. "My best friend who lives next door is starting a new school." (I have one best friend.)
4. "We bought apples bananas and grapes."

Answers:

1. Comma splice: "I enjoy reading, but my brother prefers football." (or a full stop or semicolon)
2. "However, the plan was too expensive."
3. "My best friend, who lives next door, is starting a new school."
4. "We bought apples, bananas and grapes."

• Speech: "Come here," she said. / She said, "Come here." The comma goes inside the speech marks when the speech comes first.
• Large numbers: 1,000 and 25,000 (some style guides leave out the comma in four-digit numbers).
• Dates: "On 5 May 2025, the results were published." In US style: "On May 5, 2025, the results were published."
• Addresses and places: "She moved to Leeds, West Yorkshire, last year."