Punctuation Guide: When to Use a Comma

Correct use of punctuation is important, and the most common situation you need to know about is when to use a comma. So, take a closer look at several conditions for using it. But first, bookmark Custom-writing.org where you can get an outstanding help from our experts.


How to use commas in a list

There are rarely any questions about commas when listing two items. In these cases, people are more interested in colons and dashes. You can choose one that interests you in the tag cloud.

Where to put commas, using colons in a list

When listing just two items, you don’t need to put a comma in the sentence. What about the colon—it’s used before the list to emphasize the last part of the sentence:


We asked for two things: a room and a TV.

Commas in a list of three

When you list more than three actions, objects, or clauses, put commas between all of them. Include a comma before conjunctions—this is called an Oxford comma. Some writers omit an Oxford comma in their texts but using it makes a sentence clearer and more organized.

To practice these comma rules, list some items in a sentence:


There were dozens of interesting items: books, souvenirs, old notebooks full of sketches, and colorful pens.

Oxford comma with or

That is an easy rule, isn’t it?

But what if you use or instead of and? Should you still use a comma before it?

Use of commas before or is the same. Just place it before the conjunction:


At that party, you can always choose one of three activities: dancing, swimming, or chatting.


How to use commas with quotes

How to use punctuation in a sentence with dialog? This question will not bother you anymore!

Firstly, remember to use commas that are attached to the dialog tag outside of the quotation marks.

Punctuation before quotes

Commas and quotations are loyal partners. If you introduce dialog, use a comma after the introduction:


She cried, “Look! They ruined everything!”

Comma after quotation marks

When you put dialog at the beginning of a sentence, it’s also essential to end it with a comma, not a period, when using a dialog tag:


“It was a nice year,” he concluded.

Commas with quotations after question and exclamation marks

If dialog closes with a question or exclamation mark, don’t put a comma after it:


“They are so wonderful!” he said.


Use of commas in numbers

English punctuation marks and their uses aren’t always explained with numbers. Here are some examples of sentences where you should use commas.

Using commas in numbers

Most citation styles advise to use a comma to separate digits in complex numbers:


Less than 7,000,000 people live in this country.

Commas in decimals

When writing numbers, be careful with decimals. Many students ask what punctuation marks they should use in a decimal:

  • point,
  • comma,
  • or none of them.

We advise you to use a point:


Mom, please! It costs only $5.99!


Grammar rules for dates and commas

Correct punctuation for dates is another important question. You will need his information, for sure, even if you’re not a writer—we use dates everywhere from corporate e-mails to novels.

So, how to use commas with dates?

Let’s see!

Comma after day of week

When you introduce the day of the week before the date, use a comma:


You should bring the encyclopedia back on Sunday, March 19.

How to punctuate a date that includes a day, a month, and a year?

When the date is presented before the year, place a comma between them:


He would like to arrive on September 4, 2017.

Where to place a comma when writing month and year

If you mention only the month and year, a comma shouldn’t be used:


It was a challenging task to buy strawberry in December 1989.

Does a comma go after the year in a sentence?

  • Put them before and after the year:


We bought a little kitten on April 26, 2011, and she turned into a beautiful cat.

  • Proper placement of commas in the order day-month-year is easy—you don’t need any commas:


He became a participant of the knitting club on 3 September 2016 and already knows how to create fantastic sweaters.


When to use commas before and after names?

The comma is the most popular punctuation mark in the English language. Commas before names are necessary when there is a direct address in a sentence:


Leave him alone, Phillip!

But do you use a comma after a name?

Yes, of course! Commas around names is an important rule that you can practice in dialog:


How many times, Bill, did you ask her to calm down?


How to place commas in sentences

When to use a comma in a sentence? Sooner or later everyone asks this question. In this part, we’ll try to investigate the most complicated cases of comma usage.

When we use a comma in a compound sentence

To connect two or more independent clauses in a compound sentence that has a conjunction, you need to place a comma between them:


Are you preparing for an exam, or is that a game open on your computer?

The uses of comma in a simple sentence

If there is only one independent clause in a sentence, you need no comma. This punctuation rule is true for simple sentences:


She forgot my number but not my address!

How to use a comma in a complex sentence

In complex sentences, notice the placement and connections between independent and dependent clauses.

  • If the dependent clause is important for the idea of the sentence—don’t use commas, and if it isn’t essential for the sentence—put commas before and after the dependent clause:


She didn’t take notes because she was in a hurry.


She didn’t take notes, because she was in a hurry.

  • When the dependent clause is placed before the independent one, proper use of punctuation is—always separate it with a comma:


Though she bought a present, it was difficult to go to his birthday.

  • If there are two dependent clauses before the independent one—separate only the second clause by using commas:


Because she passed the test and her room is clean, she can go to the concert.

  • Proper grammar and punctuation are more challenging to use in complex-compound sentences. A complex-compound sentence includes two or more independent clauses and at least one dependent clause.

Here are some punctuation rules and examples:

When both independent clauses come after a dependent clause, use a comma to separate these types of clauses. But there is no comma needed between independent clauses:


Though the forest was saved, the environmental situation was complicated, and the government took charge of this issue.


Commas with interrupters

Use commas to separate nonessential parts of the sentence. It can be a word such as however, therefore, moreover or phrases as in the end, of course, in addition:


The dog, of course, was surprised by this action.


Commas with adjectives

When to use commas with adjectives

To answer this question, you need to understand coordinate and cumulative adjectives.

  • Coordinate adjectives each modify the object:


He used to wear big, long pants.

Both big and long define the noun pants. That means these adjectives are coordinate and need a comma between them.

  • Now, let’s look at an example with cumulative adjectives:


He used to wear dark green pants.

Here the word dark defines not the noun pants but the phrase green pants. That’s why we don’t need to put a comma between them.

You can easily determine if the adjectives are coordinate or cumulative by placing and between them. We can say big and long pants, but the phrase dark and green pants sounds unnatural.


FAQ: When to use a comma

When do you use a comma before and after but?

Firstly, you should understand what type of sentence you have.

  • When one clause is independent, and the other is dependent, don’t use a comma. How can you distinguish them? Clauses have a subject and a verb. An independent clause makes sense by itself, while a dependent clause doesn’t express a complete thought by itself:


She bought pens but not pencils.

  • Comma usage when but connects two separate independent clauses is the following:


She bought pens, but she didn’t find where to buy pencils.

Do you use a comma before and?

To know where to insert a comma—determine the type of sentence.

  • If you connect independent and dependent clauses, you don’t need a comma:


Sarah went outside and started dreaming about the forgotten umbrella.

“…started dreaming about the forgotten umbrella” is a dependent clause, because it can’t stand by itself. So, we don’t need any punctuation before the word and.

  • When you connect two independent clauses, put a comma before and:


He’ll arrive on September 17, and Alice is already at our place.

  • Don’t forget where do commas go in the list. In academic language, you can often see Oxford commas—commas before and:


We cooked pizzas, pasta, and burgers all week.

When to use commas with however?

Comma use with however is a bit challenging, but we know you can handle it!

  • Place commas before and after however, when it separates two parts of one clause:


The children, however, continued their journey.

  • But when you connect two independent clauses, do you put a comma before however?

No, you should put a semicolon instead:


We haven’t spent a single night in the forest before; however, now we tried to sleep in our broken car and patiently wait for help.

  • You don’t use however and comma together, if you mean no matter how, in whatever manner:


However fast you run, you can’t catch this.

  • If you use however to connect two sentences, and the meaning of the adverb is nevertheless, use a comma:


The meeting was delayed until lunch; however, the agenda remained the same.

When do you use a comma before because?

Commas with because entirely depend on the meaning of the sentence.

Let’s take an example. Here’s a sentence without punctuation before because:


She didn’t come in time because the homework wasn’t done.

In this case, we’re not sure what the author means. It’s possible that the reason why she didn’t come in time isn’t connected with undone homework.

But when we put a comma into the sentence, we clarify the idea:


She didn’t come in time, because the homework wasn’t done.

This sentence means that she was late because of the homework.

When to use a comma with so in the beginning of the sentence?

When you use so with the meaning well, you should use a comma:


So, do we go to watch the new Marvel movie?

When you use so with the meaning so that, don’t put any commas:


Why did you buy snacks?
So we could save time before the party.

When to use a comma with too?

The comma use in these conditions depends on your preferences. The slight difference between the two variants of punctuation is in the emphasis in the sentence with a comma:


I adore this band, too!

When to use a comma with as well as?

If the information that goes with as well as isn’t important, you should put commas around it:


The portrait, as well as her other favorite stuff, was ready to ship to her new home.

Don’t use a comma, when as well as means in addition to:


Alex decided to throw the cigarette out of the window as well as all the worries about being caught by his parents for smoking.

When you compare two objects, things, or people, there’s also no comma before as well as:


He doesn’t drive as well as I do.

When to use a comma with such as?

  • Commas around such as are necessary when the information which follows it isn’t essential for the sentence:


Bill tried dozens of hobbies, such as football, dancing, writing, playing drums, and swimming.

  • We don’t put a comma before such as and after it when the information after it is important for the sentence:


Hobbies such as football and swimming will help Bill to strengthen his health.

To know whether the information is essential or not, imagine yourself deleting this part from the sentence. Did it ruin the meaning of the sentence? If yes, it’s an essential part.

When to use a comma with which?

  • According to modern grammar, a comma before which is added only for a nonessential clause:


Her drawing, which was hidden out of sight, laid under the bed.

  • If you use the phrase in which, there’s no comma:


The room in which she heard them talking was locked.

And you definitely don’t need any commas in direct questions:


In which drawer did you put the batteries?

Is there a comma between city and state?

When you give an address, put commas before and after the state:


The stolen Toyota was found yesterday in Miami, Florida, by a local office manager.

Comma – further study

In this article, we’ve covered the main cases of correct comma usage. Anytime you need some help with punctuation marks, open this guide and find the right answers on when to use a comma!

We developed easy navigation via tag clouds so that you can always know where to put commas.