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I’d bet that if I were to ask anyone which punctuation mark they have the most trouble understanding how to use, their answer would be “I don’t know how to use commas.”
Commas are notorious in the writing and proofreading worlds. There are several comma rules you can follow, but sometimes their use is subjective, and that’s where a lot of people (proofreaders, in particular) have difficulty. We like rules! 😉
In this article, you’ll learn what commas are used for, comma rules you need to know, and comma mistakes you need to avoid.
(Please note that I used The Chicago Manual of Style (CMOS) as my reference guide unless otherwise noted.)
Table of Contents
What Are Commas Used For?
A comma is used to indicate a smaller pause or break. It provides a weaker separation than the period.
However, that doesn’t mean you should use a comma whenever you would pause for breath in a sentence. There’s more to it than that!
Commas are one of the most used (and most abused) punctuation marks in the English language.
So how do you use commas? There are several rules you need to follow to ensure you’re using them correctly.
You can use commas with
- Coordinating conjunctions
- Lists
- Coordinate adjectives
- Dependent clauses
- Introductory clauses
- Certain introductory words
- Nonrestrictive clauses
- Appositives
- Direct address
- Dates
- Addresses
- Quotations
Commas with Coordinating Conjunctions
You can use a comma to join two independent clauses that are connected by a coordinating conjunction.
These include words like for, and, nor, but, or, yet, and so. To easily remember these conjunctions, use the acronym FANBOYS!
Examples:
We went to the zoo, and we saw the polar bears.
She thought it would be difficult, but it was very easy.
Occasionally, the comma can be omitted before a coordinating conjunction if the clauses are very short and closely connected.
One question that’s often asked is “Does the comma go before or after but?”
Answer: A comma usually precedes the conjunction but; however, if the words following the word but make up a restrictive clause, you can put a comma after but. You can choose to leave the comma after but out unless omitting it would cause confusion.
Example:
We were having a great time at the party, but, realizing the hostess was tired, we decided to call it a night.
Commas with Lists
One of the most common questions is “Can you use a comma before and in a list?” You can use a comma to separate items in a list of three or more items.
This is called the Oxford comma or the serial comma. The Chicago Manual of Style recommends the use of the Oxford comma to prevent ambiguity.
Examples:
The Irish flag is green, white, and orange.
Her parents, Ringo, and Cher were there to cheer her on.
In the second example, the comma is essential. Otherwise, some people may think that her parents are Ringo and Cher instead of two other people who are there in addition to her parents.
However, a comma is not necessary in a list of only two items.
Incorrect: He had a red ball, and a blue skateboard.
Correct: He had a red ball and a blue skateboard.
Commas with Coordinate Adjectives
You can use a comma between coordinate adjectives that describe the same noun.
To figure out if the adjectives are coordinate, ask yourself two questions:
- Can the order of the adjectives in this sentence change?
- Can I put the word and between them and it would still make sense?
If you can answer yes to those questions, then you can use a comma between the adjectives.
Examples:
She lives in the enchanting, charming house on the left.
They were generous, loving people.
Both of these sentences could be written with the adjectives in a different order or with the word and inserted between them.
If you can’t switch the order or insert the word and without the sentence sounding awkward, then the adjectives are cumulative adjectives instead of coordinate.
Incorrect: She lived in a yellow, wooden house.
Correct: She lived in a yellow wooden house.
Yellow and wooden are cumulative adjectives because it wouldn’t sound correct to switch the order. Cumulative adjectives must appear in a certain order in a sentence. See below table for the order adjectives should come in.
| Order | Type of Adjective | Examples |
| 1 | Determiner | A, the, this |
| 2 | Quantity | Two, four, three hundred |
| 3 | Opinion | Attractive, stupid, charming |
| 4 | Size | Large, tiny, small |
| 5 | Physical quality | Fat, smooth |
| 6 | Age | Young, old, middle-aged |
| 7 | Shape | Round, square, oblong |
| 8 | Color | Blue, yellow, pastel |
| 9 | Proper adjectives (i.e., ethnicity, religion, etc.) | Irish, Catholic |
| 10 | Material | Wooden, metal |
| 11 | Purpose | Writing, eating, swimming |
| 12 | Noun | House, car, boat |
Commas after a Dependent Clause
When a dependent clause introduces the main clause, a comma should follow it.
Examples:
If you don’t clean your room right now, I’m going to kill you!
When we finish school, we’re going to travel.
However, don’t put a comma after a main clause that is followed by a dependent or subordinate clause if it is restrictive (i.e., essential to understanding the meaning of the main clause).
Examples:
I’m going to kill you if you don’t clean your room!
We’re going to travel when we finish school.
Commas after an Introductory Clause
A comma may or may not follow an introductory word or phrase. This is where it gets subjective. A writer or editor can choose to omit the comma if the meaning is clear without it.
Examples:
Every evening, they sat down to eat dinner together.
On Tuesdays, they ate pork chops.
You could omit the comma in both of these sentences if you prefer.
Example of when a comma is necessary in an introductory phrase:
Incorrect: Before eating the children washed their hands.
Correct: Before eating, the children washed their hands.
You can see how misreading could occur with this example (before eating the children…!).
Commas after Certain Introductory Words
Commas usually follow certain words that begin a sentence like yes, no, well, oh, ah, etc.
Examples:
Yes, I do think you can become a successful proofreader.
Well, we really should eat something first.
Oh, I didn’t know you were a millionaire!
Commas with Nonrestrictive Clauses
A nonrestrictive clause provides extra information about something, but this information is not necessary for your reader to understand the sentence. You can use a comma to set off nonrestrictive words and phrases.
Examples:
My daughter, who is wearing a red dress, won the award.
Who is wearing a red dress is extra information about your daughter that isn’t necessary for the reader to understand who won the award.
My daughter who is wearing a red dress won the award.
If you remove the commas, it implies that you have more than one daughter, but it was the one wearing the red dress who won the award. The information is restrictive in this case.
Commas with Appositives
An appositive is a noun phrase that provides explanatory or additional information about another noun. Use commas to set off appositives.
Examples:
The headmaster, an angry man, witnessed the kids sneaking out the back gate.
Her brother, John, was at the party as well.
This second example brings up a tricky situation. It implies that she has one brother and his name is John. His name is extra information that isn’t necessary for understanding the sentence. It is nonrestrictive information.
Her brother John was at the party as well.
When you omit the commas, it implies that she has more than one brother, so providing his name is necessary for us to understand which brother was at the party.
Commas with Direct Address
Use a comma (or commas) to set off a person’s name when they’re being addressed directly. This applies to nicknames and terms of endearment as well.
Examples:
Jane, dear, you need to put the work in, or you won’t see the results!
Hey, buddy!
Did you make my lunch, Mom?
Commas with Dates
If you follow the month-day-year style of dates, commas are usually used to separate the day of the month from the year.
Examples:
It all began on June 5, 2013.
The special offer began on September 6, 2018, and ran until January 6, 2019.
We met on Friday, April 3, 2020.
If the year is mentioned midsentence, it needs to be followed by a comma as well. A comma should also follow the day of the week in this type of construct.
However, if you are only referencing the month and the year, you do not need to use a comma.
Example:
It was the October 2017 edition.
In contrast, the day-month-year style of dates common in British English doesn’t require a comma.
Example:
It all began on 5 June 2013.
Commas with Addresses
Use a comma to separate a city from its state, province, or country.
Examples:
I’ve been living in Dublin, Ireland, since 2008.
She visited San Francisco, California, right after she finished school.
Use a comma to set off separate lines of an address.
Example:
Dory set off to find P. Sherman, 42 Wallaby Way, Sydney.
Commas with Quotations
A comma usually precedes a direct quotation if the quotation is introduced with words like said, asked, replied, etc.
Examples:
Jack said, “I have never been to the zoo.”
It was Catherine who said, “Commas aren’t so bad once you learn how to use them.”
“Well,” Mark said, “that’s that then.”
Related Content:
Colon vs. Semicolon: When and How to Use Them
How to Use an Apostrophe (and Mistakes You Need to Avoid)
En Dash vs. Em Dash: When and How to Use Them
How to Use Quotation Marks (and the Difference between Single Quotes vs. Double Quotes)
How to Use an Ellipsis: Chicago vs. AP Style
Comma Mistakes to Avoid
I covered some instances when you don’t need to use a comma above, but here are some instances when you really need to avoid using a comma.
Don’t Use Commas with Run-On Sentences
Run-on sentences or comma splices are one of the most common ways commas are misused. You’ll often see this error on social media. It happens when two independent clauses are run together without using a coordinating conjunction.
Example of a comma splice:
I tasted her food, it wasn’t good.
To fix the comma splice, you could rewrite the sentence in the following ways:
- Add a coordinating conjunction
-
- I tasted her food, and it wasn’t good.
- Make it two separate sentences by adding a period
-
- I tasted her food. It wasn’t good.
- Use a semicolon to separate two independent clauses
- I tasted her food; it wasn’t good.
Don’t Use Commas with Restrictive Clauses
A restrictive clause is when a clause is essential to the meaning of the sentence.
Example of a restrictive clause:
The swimmer who won the race got the award.
In this example, who won the race is essential to the meaning of the sentence. They’re getting the award because they won the race. This means that it is a restrictive clause and commas should not be used.
The swimmer, who won the race, got the award.
In the second example, the fact that the swimmer won the race is supplemental. We’re not necessarily saying that they won the award because they won the race. The award could be for something else.
Don’t Use Commas with Compound Predicates
A compound predicate occurs when a subject that has two or more verbs is not repeated after the first verb.
A comma should not separate a subject from its verb, so if the subject doesn’t appear in front of the second verb, don’t use a comma.
Examples:
Incorrect: He got out of bed, and ran straight to school.
Correct: He got out of bed and ran straight to school.
Correct: He got out of bed, and he ran straight to school.
Incorrect: I intended to go to the party, but fell asleep after dinner.
Correct: I intended to go to the party but fell asleep after dinner.
Correct: I intended to go to the party, but I fell asleep after dinner.
Comma Quiz
Punctuate these sentences with commas where necessary. You can find the answers at the bottom of this post.
- They got married in Mobile Alabama on July 7 1959.
- Frankly my dear I don’t give a damn.
- My favorite ice cream flavors are chocolate mint and salted caramel.
- There were highs and there were lows.
- They lived next door to the kind gentle giant.
Related Post: Punctuation Myths That Refuse to Die
Final Thoughts on How to Use Commas
I hope you now have all the information you need to use commas correctly. Don’t forget to take the quiz to cement what you’ve learned!
Need More Grammar and Punctuation Help?
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If you’d like to improve your grammar and punctuation skills so you can communicate better or hone your proofreading skills, Grammar Lion: A Grammar Refresher is an in-depth but easily digestible course.
Here’s what you’ll learn:
- Learn how to identify the parts of speech
- Recognize and correctly use commonly mixed-up words
- Spot sentence fragments, and rework them into complete sentences
- Master the rules of punctuation and capitalization
- And much more
Commas tripping you up? Take this free comma course to refresh your knowledge.
If you want to learn more, here’s my review of the Grammar Lion course.
Further Reading
Comma Quiz Answers
- They got married in Mobile, Alabama, on July 7, 1959.
- Frankly, my dear, I don’t give a damn.
- My favorite ice cream flavors are chocolate, mint, and salted caramel.
- There were highs, and there were lows.
- They lived next door to the kind, gentle giant.
