Commas matter. That tiny period-with-a-tail can change the meaning of your entire sentence, and your use of it quickly demonstrates just how well you know the English language. Here are 8 comma rules writers should know and use.
Today, I have just a few comma tips for you. This is nowhere near an exhaustive guide, but if you learn these rules, you'll give a better impression with your written word everywhere you go.
The Purpose of Commas
The biggest confusion regarding commas stems from a terrible urban legend. That urban legend is this: “If you want to know where a comma goes, just put it wherever you want a pause in your writing.” (And then say “comma” three times in front of a mirror, etc.)
This is not true.
Commas serve a specific purpose; they exist to divide content by clause, to delineate list items from one another, and to indicate sentence continuation before and after quotation marks.
Generally speaking, commas only show up for clarity's sake—and I'll be explaining how they clarify in each of the following examples.
8 Comma Rules: When to Use Commas
1. Use commas with dates and addresses
We'll start with the easy ones: use commas with dates and addresses.
In the United States, when dates are written out, use a comma after the number indicating the date:
- July 25, 2023
When writing out an address in a sentence or paragraph, use a comma after the street and after the city
- 1234 S. Elm Street, Birchwood, NC 27215
When the address is stacked for a mailing address on an envelope or package, use a comma after the city only:
- Charlie Smith
1234 S. Elm Street
Birchwood, NC 27215
2. Use Commas Between Items in a Series
In a list, two items never require a comma. Three or more, however, do. For example:
- I can go to the store for milk and eggs. (No comma required.)
- I can go to the store for milk, eggs, and bread. (Comma required.)
This applies to subjects, too. Two subjects do not require a comma; three or more do.
- INCORRECT: Sandy, and Jim went to the store. It should just be “Sandy and Jim went to the store.”
- Sandy and Jim went to the store. (Huzzah, correct!)
- Sandy, Jim, and Carlos went to the store. (Also correct.)
Three or more verbs require a comma, too.
- Shirley Temple sang and danced. (Correct.)
- Shirley Temple sang, danced, and acted. (Also correct.)
Compound verbs (that is, multiple verbs that describe a single action) can get complicated, but if you follow the “three or more” rule, you can usually make it work.
- I took the spatula and stirred. (Compound verb: took and stirred.)
- I took the spatula, scraped the icing, and stirred the mixture until smooth. (Three parts to this compound verb = comma. Also, bonus points for noticing parallel structure here!)
Some will argue you don't need that last comma, sometimes called the serial comma or the Oxford comma. You can read all about that here. In short though, clarity always wins, and the Oxford comma is clear in nearly every context. (And necessary in some style guides and legal documents!)
3. Use Commas Before (NOT After) Conjunctions that Join Independent Clauses
Coordinating conjunctions are those tiny words that join other words or sentences or clauses together. (“Or” is the conjunction in that last sentence, you see?) In school, you may have learned an acronym to remember them: FANBOYS. For, And, Nor, But, Or, Yet, So.
Independent clauses include a subject and a verb AND can stand alone.
Example: She took a nap. (subject: she; verb: took; complete as a sentence.)
When you combine two or more independent clauses, use a comma and a coordinating conjunction. The comma comes before the conjunction. It doesn't come after. I've actually seen this error multiple times:
- INCORRECT: She took a nap and, she made a sandwich.
- CORRECT: She took a nap, and she made a sandwich.
The first independent clause is “she took a nap” and the second one is “she made a sandwich.” Note: this type of sentence construction is also called a compound sentence.
If you didn't want to use a comma, you could simply make the verb compound by removing the second subject in the sentence. Like this:
She took a nap and made a sandwich.
Although it might be hard to make a sandwich while taking a nap?
4. Use Commas to Set Off Nonrestrictive Phrases and Clauses
A nonrestrictive phrase or clause is one that gives extra information. Meaning, we don't need the information to understand the sentence. For example:
- Charlie, who lives next door to me, just got a new car.
The nonrestrictive clause here is “who lives next door,” and it is set off by commas. We could take that clause out of the sentence and the meaning doesn't change.
Another type of nonrestrictive phrase is the appositive. Appositives offer more information about nouns. Again, if the appositive gives info that isn't needed to understand the sentence, it is set off by commas. Example:
- Charlie, the man next door, just got a new car.
When you give extra information, check to see if you need a comma to set it off in the sentence.
5. Use Commas to Introduce/Identify Spoken Dialogue
Quotation marks are what we use in English to indicate spoken word, as opposed to narrative voice or inner thought. Commas are needed to add dialogue tags (“he said,” etc.) and to connect the words to their speaker. For example:
- “I like her voice,” he said. (The statement between quotation marks is complete, but we don't use a period because “he said” has to be attached to it to identify the speaker.)
- I said, “Are you out of your mind?” (Again, between the quotation marks, the sentence is complete, but we need the comma after “I said” to link the words to the speaker.)
The only exceptions for this are when a different punctuation mark is required inside the quotation marks and the dialogue tag still comes after the statement. For example, if someone asks a question:
- “Do you like her voice?” he said. (Note that “he” is lowercase, even though there's no comma.)
- I said, “Can you turn that down?” (The quotation mark is attached to the statement inside the quotation marks, but the dialogue tag still requires a comma when the tag comes before the statement.)
Just remember: a dialogue tag generally requires a comma. If the tag comes before the quotation marks, a comma is always required. If it comes after, the dialogue tag is almost always lowercase.
6. Use Commas on Both Sides of An Interruption
Commas are used to set off an interruption in the sentence. FYI, it's crucial to remember to close that interruption with a second comma. For example:
- The challenge, in the final analysis, was finding a way out of the tunnel. (“in the final analysis” is an interruption. You could actually remove it without changing the sentence's meaning.)
- Jackie, of course, had a different opinion. (“of course” is an interruption. It lends personality and flavor to the sentence, but could be removed without changing the meaning.)
- My cats, without question, are the cutest in the world. (“without question” is an interruption and can be removed.)
7. Introductory Phrases Need a Comma
If an introductory phrase in a sentence is more than four words, use a comma to set it off from the main clause in the sentence. For example:
- When she gets here, we'll go to the store. (When she gets here is a conditional introductory clause and needs the comma to set it off from the main independent clause in the sentence.)
- After the dinner and show, we plan to crash the cast party at the hotel.
8. Use a Comma With Coordinate Adjectives
Coordinate adjectives are describing words that hold equal weight as they describe a noun. When you use them in a sentence, you use a comma after the first one to be clear that you are using adjectives in a short list. Example:
- The wise, old teacher knew how to use coordinate adjectives.
Here, the adjectives “wise” and “old” are used one after the other to describe the teacher. You could write “wise and old teacher,” but it changes the flow of the sentence.
When Not to Use Commas
Don't Use Commas Between Subject and Predicate
The subject is the primary subject of the sentence (hence the name). The predicate is what the subject does, what's done to the subject, or some identifying detail about the subject. There should be no comma between them. Why? So the reader sees they're linked (remember, a comma divides).
- INCORRECT: The car, was fast. (“The car” is the subject; “was fast” is the predicate.)
- CORRECT: The car was fast.
- INCORRECT: Phoenix, is warm in the summer. (“Phoenix” is the subject, and “is warm” is the predicate.)
- CORRECT: Phoenix is warm in the summer.
This only gets complicated when you have multiple subjects, but even then, as long as you apply the “three or more” rule, you'll be fine. For example:
- Tom and Harry went to the store. (Multiple subjects, but only two—thus, no comma.)
- Tom, Harry, and Jane went to the store. (Three subjects require a comma.)
Don't Use Commas With Subordinate Clauses
You may recall that commas are required between clauses—that is, between complete subject-predicate sentences. That means if you have a subordinate clause (a sentence snippet that isn't complete), you do NOT need a comma.
If you want to use a comma between clauses, ask yourself this question: is there a subject and predicate on both sides?
A few examples:
- CORRECT: He stepped into the room to explain his side.
- INCORRECT: He stepped into the room, to explain his side. (“to explain his side” is not a complete clause, so no comma is required.)
- CORRECT: Tony likes carrot-cake because it makes him happy.
- INCORRECT: Tony likes carrot-cake, because it makes him happy. (“because it makes him happy” is a sentence fragment.)
- CORRECT: Sandra sings the blues with great passion.
- INCORRECT: Sandra sings the blues, with great passion. (“with great passion” can't stand on its own.)
If this is confusing, I suggest you study sentence fragments. Once you learn what they are and how they work, you'll spot them, and you'll be able to avoid putting a comma anywhere near those things.
Don't Use a Comma Between Two Clauses WITHOUT a Conjunction
This is called a comma splice, and it's the bane of editors everywhere. Remember how a complete clause has both a subject and a predicate? Complete clauses require either a full stop between them or a conjunction to join them together. Without a conjunction, you have a run-on sentence, also called a comma splice:
- INCORRECT: Talia worked hard, her dinner tasted great. (Talia and dinner are both subjects; worked hard and tasted great are both predicates. Those are two complete sentences.)
- CORRECT: Talia worked hard, and her dinner tasted great.
- ALSO CORRECT: Talia worked hard. Her dinner tasted great.
- ALSO CORRECT: Talia worked hard; her dinner tasted great.
If a clause can stand on its own, it's a complete sentence. If that clause is complete, don't join it to another one without a comma.
- INCORRECT: Joe picked the clover, he couldn't believe it had four leaves.
- CORRECT: Joe picked the clover. He couldn't believe it had four leaves.
- INCORRECT: Marston sheathed his sword, he knew the enemy would return.
- CORRECT: Marston sheathed his sword for he knew the enemy would return.
Final Thoughts on Commas
This can all seem pretty confusing if you've never encountered these rules before. Subject, predicate, clause… I keep using crazy words like that, but for a reason. These are all identified parts of speech, and knowing how they work is crucial to clear communication. If you want your readers to believe you know what you're doing, learn to use the comma. It will give your readers confidence in your writing, and will ensure your editor's good will.
Quick tip: A great way to learn comma usage is to READ A LOT. Go to your library and sign up. Prefer e-books? Still sign up at your library, then use Overdrive to get e-books right on your reader. The more you read, the more you'll learn. Read with your thinking cap on, and before you know it, you'll be writing like a pro.
Do you ever run into trouble using commas? Let me know in the comments!
We all struggle with comma-usage (yes, even me). For the next fifteen minutes, write the next part of your WIP (or use one of these writing prompts) and try to use several types of commas (in a list, with conjunctions, etc.) correctly. It can be messy; we're not looking for polished drafts here! Just do your best and post it in the Pro Practice Workshop here. Don't forget to spot-check three other people's work, as well!