Blog / Comma Mistakes: 35 Real Examples and How to Fix Them

Comma Mistakes: 35 Real Examples and How to Fix Them

Commas cause more questions than any other punctuation mark, partly because some comma rules are firm and others are matters of style. The examples below are real sentences that people sent to Proofread Bot, grouped by the rule involved.

The corrections are written in formal, academic English, so contractions are spelled out in full. Where a contracted or colloquial form is common in everyday writing, it is shown underneath as the informal version.

1. After an introductory word, phrase, or clause

Put a comma after an element that comes before the main clause.

✗ However I like this idea.
✓ However, I like this idea.

✗ Furthermore Buck knew he could not rely on the new men.
✓ Furthermore, Buck knew he could not rely on the new men.

✗ In addition I would like John to get involved.
✓ In addition, I would like John to get involved.

✗ When it started raining we went inside.
✓ When it started raining, we went inside.

✗ Because of his training program Bill refused the apple crisp.
✓ Because of his training program, Bill refused the apple crisp.

✗ By pressing ahead with the BFR Musk is accelerating the push.
✓ By pressing ahead with the BFR, Musk is accelerating the push.

✗ Yes I like pizza.
✓ Yes, I like pizza.

With a very short introductory phrase ("In 2020 the law changed"), the comma is optional. After transition words like however, furthermore, and moreover, it is required.

2. Between items in a list

✗ I bought apples cherries bananas and grapes.
✓ I bought apples, cherries, bananas, and grapes.

✗ John Locke Voltaire Adam Smith and Mary Wollstonecraft all argued that society could be improved.
✓ John Locke, Voltaire, Adam Smith, and Mary Wollstonecraft all argued that society could be improved.

✗ The office worker possessed a jacket. A laptop. And a briefcase.
✓ The office worker had a jacket, a laptop, and a briefcase.

✗ I like cooking my dog and family.
✓ I like cooking, my dog, and my family.

The comma before "and" in a list is the serial or Oxford comma. It is optional in British English and in journalism, but most academic style guides (APA, Chicago, MLA) require it. The last example shows why: without commas, the sentence describes a crime.

3. Between two independent clauses joined by "and," "but," or "so"

When and, but, or, so, or yet joins two complete sentences, put a comma before it.

✗ Tom reads novels but Jack reads comics.
✓ Tom reads novels, but Jack reads comics.

✗ I like to cook and grandma likes to eat.
✓ I like to cook, and Grandma likes to eat.

✗ I used to play but now I do not.
✓ I used to play, but now I do not.

✗ I am very tall whereas my wife is quite short.
✓ I am very tall, whereas my wife is quite short.

4. Not between a verb and its second action

If the second part has no subject of its own, it is not an independent clause, and there should be no comma.

✗ He went to the store, and bought candy.
✓ He went to the store and bought candy.

✗ She was confused, and wanted to know more.
✓ She was confused and wanted to know more.

✗ I could not decide if I should continue writing, or go to bed.
✓ I could not decide whether I should continue writing or go to bed.

5. Not before "because" at the end of a sentence

✗ I went to bed, because I was tired.
✓ I went to bed because I was tired.

✗ I washed my dog yesterday, because he smelt awful.
✓ I washed my dog yesterday because he smelled awful.

When a dependent clause (because, since, although, when) comes after the main clause, it usually takes no comma. When it comes first, it does (see rule 1).

6. Around extra information

Information that could be removed without changing the meaning of the sentence goes between a pair of commas. Forgetting the second comma is the most common error.

✗ Arlene Blum, visiting scholar at UC Berkeley talks about bottled water.
✓ Arlene Blum, a visiting scholar at UC Berkeley, talks about bottled water.

✗ My cat Henry who likes fish sleeps on my bed.
✓ My cat Henry, who likes fish, sleeps on my bed.

✗ Jonas a young boy ran to the car.
✓ Jonas, a young boy, ran to the car.

✗ I'm from Clinton Mississippi and I want to go to college in Jackson Mississippi.
✓ I am from Clinton, Mississippi, and I want to attend college in Jackson, Mississippi.

7. When addressing someone

✗ Let's eat grandma.
✓ Let us eat, Grandma.
Informal: Let's eat, Grandma.

✗ Good morning Mom!
✓ Good morning, Mom!

✗ Hello my name is Dave.
✓ Hello, my name is Dave.

8. Commas that do not belong

✗ I love pizza, and cake.
✓ I love pizza and cake.

✗ Sally had a picnic, on the grass.
✓ Sally had a picnic on the grass.

✗ There is, a long stick on the driveway.
✓ There is a long stick on the driveway.

✗ Reflecting telescopes have two mirrors which, reflect light off each other.
✓ Reflecting telescopes have two mirrors that reflect light off each other.

Never put a single comma between a subject and its verb, or between a verb and its object.

9. Comma splices

✗ Dan was late, we left without him.
✓ Dan was late, so we left without him.

✗ Our spring musical will occur in March, however, it will still be very cold outside.
✓ Our spring musical will take place in March; however, it will still be very cold outside.

A comma alone cannot join two complete sentences. Use a period, a semicolon, or a comma plus a conjunction. However between two sentences needs a semicolon before it.

10. Spacing

✗ I hate green beans,corn,and apples.
✓ I hate green beans, corn, and apples.

✗ I like apples , mangoes and bananas.
✓ I like apples, mangoes, and bananas.

A comma is followed by a space and never preceded by one.

Proofread Bot checks each of these rules and explains why a comma should be added or removed. For quotation marks and citations, see punctuation with quotation marks and citations.

Revisar agora