Comma Rules

When to Use a Comma

The comma is a frequently used type of punctuation that helps separate words and ideas in a sentence. Writers can use a comma in many different ways. Below are some examples of the proper comma rules.

Comma Rules in a Series

Comma Rules: When listing three or more items, insert a comma after all of the items except the last one.

What is a Comma?
Over the next two weeks, I’ll be traveling to California, Nevada, Utah, and Colorado.
Benjamin Franklin invented the lightning rod, bifocal glasses, and a special stove.
Kimeko gathered her materials, packed her lunch, and headed to school.
We went swimming, dug for clams, and built sand castles at the beach.


Comma Rules Between Adjectives

Comma Rules: When using two or more adjectives to describe someone or something, insert a comma between the adjectives.

Candied almonds are a sweet, spicy snack.
The haunted house in the movie sat at the edge of a dark, ominous forest.
I’ll put the warm, blue, knitted blanket on the bed.
The sweet, babbling, laughing baby lit up the room.

Comma Rules: Generally, do not insert a comma after adjectives that indicate either a number or the size, shape, or age of something or someone.

I’m going to use the square black pan to make the brownies.
My old gray shoes need to get repaired.
Cecily and Ryan have three small children.
We watched the gigantic white boat sail across the lake.
Five brown ants crawled across our picnic blanket.


Comma Rules with Introductory Elements

Comma Rules: Insert a comma after introductory words and mild interjections that come at the beginning of a sentence.

Therefore , we will probably be a few minutes late to the party.
However , Hillary said she could come over this morning to help us move.
Furthermore , I’m concerned about what the weather will be like this weekend.
Well , I’m not exactly sure when I’ll get home.

Insert a comma after an introductory prepositional phrase if it contains at least one additional prepositional phrase. You don’t need to use a comma if either the sentence starts with just one prepositional phrase (unless you’d naturally pause after saying it aloud) or the prepositional phrase is very short.

Comma Rules: At the end of the street, take a left turn.
Near the steps by the front door , you’ll find your jacket.
By the end of the day , we’ll be tired from our bike ride.
Across the hall from the master bedroom , there’s a guest room.
Past the gates by the barn , horses are running in the field.

Comma Rules: Insert a comma after a verbal phrase that comes at the beginning of a sentence.

Slipping across the ice , the car finally came to a stop.
Barking at passersby , the dog protected its territory.
Sparkling in the sunlight , the lake looked inviting to the swimmers.
To increase their sales , authors go on book tours.
To improve his test scores , Roman spent a lot more time studying.

Comma Rules: Insert a comma after an introductory adverb or adverb clause that comes at the beginning of a sentence.

Consequently , we will need to reassess our business plans.
Apparently , Veronica forgot to inform her coworker about the upcoming deadline.
Eventually , Lucien decided to join our soccer team.
When the rain started coming down , we ran under a tree for shelter.
If we put too many things in our backpacks , they’ll be too heavy to carry.


Comma Rules with Interrupters

Comma Rules: Insert a comma around parenthetical expressions—words, phrases, or clauses that interrupt other words, phrases, or clauses.

This book is, frankly , the most boring one I’ve ever read.
Orson Welles was, I think , the best movie director.
Shrimp, for example , is a type of shellfish many people are allergic to.
The Wilsons are going to be late getting here, I suspect , because traffic is bad.
Dark chocolate is sometimes referred to, strangely enough , as a “super food” because it contains so many antioxidants.

Comma Rules: Insert a comma to set off words of direct address, such as names, titles, or terms of respect.

Doctor , could you let us know how the patient is doing?
Would you like some coffee, Ms. Hughes ?
Thank you, Damon , for helping me unload groceries from the car.
Judge , I would like to call the next witness to the stand.
Yeah, Mom , let’s get pizza tonight!


Comma Rules with Nonessential Information

Comma Rules: Insert a comma to set off nonessential clauses, participles and participial phrases, and appositives and appositive phrases. Nonessential elements add additional information that isn’t necessary for understanding a sentence’s meaning.

A tabby coloring, which is common in cats , consists of streaks of dark stripes.
Hazelnuts, which are also sometimes called filberts , add a great flavor to desserts.
Juliette, stretching on her mat , waited for yoga class to begin.
Nick, a boy I went to school with , is coming to the class reunion.
Ludwig van Beethoven, a famous composer, was born in Germany.


Comma Rules in Compound Sentences

Comma Rules: Insert a comma before the coordinating conjunction that joins two independent clauses in a compound sentence.

Noah tried to make the turn, but his bike skidded in the leaves and crashed.
I’m either going to take piano lessons, or I’m going to take guitar lessons.
Elena sent in her university applications, and then she spent weeks nervously waiting for responses.
Rachel wanted to throw a surprise party for her brother, so she secretly sent out invitations to his friends.
I’m excited about my acting class, but I’m afraid of performing in front of big groups of people.


Comma Rules with Quotations

Comma Rules: Insert a comma in direct quotations to set off words telling who is speaking. Always place a comma inside of a closing quotation mark.

Comma Examples
Brad asked, “Can I get a ride with you?”
“I’ve got some big news,” Louis announced.
Sophia said sweetly , “Thank you so much for the great birthday present!”
“Everyone, please come to the dinner table,” Dad said .

Comma Rules in Dates

Comma Rules: Insert a comma between a day of the month and a year. If a date is part of a sentence, then insert a comma after the year as well. If only a month and a year are given with no specific day, then do not include a comma.

We’ll be flying to Spain on December 12, 2015.
My parents’ 20th wedding anniversary party will be held on August 15, 2016 .
On June 14, 2014 , Lisa and Kurt got married.
I’m going to make sure I watch the meteor shower on December 13, 2015 , since I missed the last one.
Shawn’s little brother was born in September 2006 .


Comma Rules in Places

Comma Rules: Insert a comma between a city and its state, country, or province. If a place is part of a sentence, then insert a comma after each item in the place’s name.

Next year my family is traveling to Orlando, Florida .
Mika is an exchange student from Tokyo, Japan
Whistler, British Columbia , is famous for its great skiing conditions.
We’ll stay at a hotel in Moab, Utah , when we visit Arches National Park.
Vienna, Austria , is well known for its coffeehouses.


Comma Rules in Letters

Comma Rules: Insert a comma after the salutation of a friendly letter and also after the closing of either a friendly letter or business letter.

Dear Muriel,
Thank you for your gift!
Hello Mark,
It was great to see you when we were recently in town.
Tim Warner
With love,
Aunt Grace


Comma Rules in Names

Comma Rules: Insert a comma between a person’s name and any abbreviation or acronym that follows it. Many, though not all, businesses follow a similar practice by inserting a comma between their names and any accompanying abbreviations or acronyms.

I got a business card from Samantha Jones, M.D.
At the conference, I spoke to Francesca Gasparotto, Ph.D.
My lawyer is Phyllis Davis, J.D.
His business is listed in the directory as Johanowicz and Sons, LLC.
We bought our garden pots and furniture from Earthen Places, Inc.


Comma Rules in Numbers

Comma Rules: In numbers insert a comma after every third digit from the right. (This rule does not apply to zip codes, phone numbers, or house numbers.)

We experienced an elevation change of over 4,000 feet on our hike.
The temperature of lava generally ranges from 1,300 to 2,200 ºF.
Homo sapiens came into existence approximately 150,000 years ago.
The distance between New York City to Los Angeles is nearly 3,000 miles.
Chicago’s population is approximately 2,700,000 .