Using Commas

The Rules for Using Commas

Commas are dividers. They are used to divide long texts into shorter, single-function sections. The main job of commas is to make text easier to read by showing the boundaries of words, phrases, and clauses with specific grammatical roles in your sentence.

The secret to using commas accurately is understanding what parts of a sentence are supposed to be grouped by commas. As we will cover, there are 10 ways to use commas.

Table of Contents

10 Ways to Use Commas
Use of Commas Explained in Detail
(1) Using a Comma after "Setting the Scene"
(2) Using a Comma after a Transitional Phrase (e.g, "However," "As a result")
(3) Using a Comma after an Interjection
(4) Using a Comma before a Conjunction
(5) Using Commas for Parentheses
(6) Using Commas in Lists
(7) Using a Comma after a Long Subject
(8) Using Commas in Numbers
(9) Using a Comma before Speech Marks
(10) Using Commas with the Vocative Case
Test Time!

10 Ways to Use Commas

Mastering commas is an essential part of becoming a competent writer. There is no generic rule that covers how to use commas. In other words, you cannot learn a simple rule like "a comma is used for a slight break." There are, in fact, 10 ways to use commas.

(1) After setting the scene at the start of a sentence.

For example:

Now that I am older, I understand.

(2) After a phrase like "however," "consequently," or "as a result."

For example:

As a result, I now understand.

(3) After an interjection (e.g., an expression of joy or surprise).

For example:

Wow, I see your point.

(4) Before a conjunction (e.g., "and," "but") that joins two "sentences."

For example:

I like cake, and I like cheese.

(5) As parentheses around additional information (i.e., like brackets).

For example:

Janet and John Baxter, who live next door, adore cakes.

(6) To separate list items.

For example:

bread, milk, and cheese ()
bread, milk and cheese ()

(7) After a long subject if it helps the reader.

For example:

A, B, C, and D, are required to bake this cake.

(8) In numbers.

For example:

3,213

(9) With direct address (also called "the vocative case").

For example:

I know your auntie, John.

(10) Before a quotation.

For example:

She said, "I understand."

Use of Commas Explained in Detail

This section explains when to use commas in more detail and gives examples for each type of comma usage.

Comma? Take a Breath

At school, many of us were taught that a comma is where you take a breath. This is fairly good advice when you're reading someone else's work aloud. However, it is terrible advice when you're thinking about where to put commas in your own work.

The ten rules for using commas are listed above and detailed below. The idea that you should put a comma whenever you want your reader to take a breath is wrong.

That's a reading technique not a writing technique.

(1) Using a Comma after "Setting the Scene"

It is quite common for a sentence to start with words which "set the scene." These words usually state a place, a time, a condition, or a fact before the main part of the sentence. Words that "set the scene" at the start of a sentence are usually followed by a comma. You do not have to use a comma; i.e., it is not a strict ruling. It's just a common style. However, as it will help your reader, it is a useful style to adopt. For example:

In Paris, they simply stared when I spoke to them in French.
At exactly 4 o'clock, two of the kidnappers re-entered the room.
If you don't know where you are going, you will probably end up somewhere else. (Author Laurence J. Peter)
As you were born here, it makes sense for my group to take the map.

Often, the words that "set the scene" are a little harder to spot:

When a man tells you that he got rich through hard work , ask him "Whose?" (Journalist Don Marquis)

These "scene setting" words (or adverbial clauses or adverbial phrases as they're really called) vary hugely. You do not have to use a comma after an adverbial clause or phrase, but a comma will make it clear where the main clause starts. When an adverbial clause or phrase is very short (e.g., Nowadays, Now, Yesterday, Today), you are safer to omit the comma. For example:

When I was a boy, I was told that anybody could become President. Now I'm beginning to believe it. (American lawyer Clarence Darrow)

When an adverbial clause or phrase is at the end of a sentence, there is usually no need for a comma before it. When it is in the middle of a sentence, you should use commas (i.e., one at the start and one at the end) if you think the commas will help the reader. For example:

Two of the kidnappers re-entered the room at exactly 4 o'clock.
Two of the kidnappers, at exactly 4 o'clock, re-entered the room.

(2) Using a Comma after a Transitional Phrase (e.g, "However," "As a result")

using a comma after a conjunctive adverb like however

A transitional phrase is a term like However, Consequently, Therefore, and As a result. (There are others, but these are the most common.) A transitional phrase sits at the start of a sentence and acts like a bridge to an idea in the previous sentence. A transitional phrase is usually followed by a comma. For example:

John has eaten at least two cakes a day for the last decade. As a result, he has been placed in a high-risk group for diabetes.
I think. Therefore, I am. (French philosopher Rene Descartes)
All progress is initiated by challenging current conceptions, and executed by supplanting existing institutions. Consequently, the first condition of progress is the removal of censorships. (Irish playwright George Bernard Shaw)
Orthodox medicine has not found an answer to your complaint. However, luckily for you, I happen to be a quack.

A transitional phrase (or conjunctive_adverb as you will hear them called) is never preceded by a comma. You can, on occasion, precede it with a semicolon (or a dash replacing a semicolon), but never a comma. That's called a run-on error.

Read more about using a comma after a transitional phrase.

(3) Using a Comma after an Interjection

An interjection is usually a short word inserted into a sentence to express an emotion or feeling. Expressions such as yes, phew, and indeed are examples of interjections. Often, an interjection sits at the start of the sentence but not always. It is normal to offset an interjection with a comma (or commas if it's in the middle of the sentence). In the examples below, the interjections are shaded:

Oh great, the boiler's broken down.
Yes, that's three out of three.
I understand your predicament, but, crikey, there is nothing we can do.

Note: If the interjection is to express a powerful emotion or feeling (and it's not in the middle of your sentence), then it can be followed by an exclamation mark.

Read more about using a comma after an interjection.

(4) Using a Comma before a Conjunction

Words like and, or, and but are known as conjunctions. (There are other conjunctions, but these three are the most common.)

When a conjunction joins two standalone sentences (or independent clauses), it is usual to place a comma before it. For example (conjunctions shaded):

Lee can sing, and he can dance

and

Lee can sing, and dance

and

Using Commas in Lists

Here are some real examples:

No amount of time can erase the memory of a good cat, and no amount of masking tape can ever totally remove his fur from your couch. (American author Leo Buscaglia)
When you have got an elephant by the hind leg, and he is trying to run away, it's best to let him run. (US President Abraham Lincoln)

(5) Using Commas for Parentheses

using commas like brackets or parentheses

We all know that additional information (such as an explanation or an afterthought) can be offset with brackets. However, brackets are just one of the choices you have. You can also use commas or dashes. The information which is offset by commas, brackets, or dashes is called a parenthesis. The punctuation marks used to offset a parenthesis (i.e., dashes, brackets, or commas) are called parentheses.

Examples (with each example of parenthesis shaded):

The case has, in some respects, been not entirely devoid of interest.
At 4 o'clock yesterday, David Frost, a cleaner from the Lakes Estate, was charged with "dog napping" his former headmaster's poodle.
Joanne Baxter, who originally appeared as a witness, has been found guilty of handling stolen goods.

who

which

relative pronoun

Commas are often more suitable for formal writing than brackets, as brackets can make your work look a little unorganized. Also, commas are often preferable to dashes because dashes are quite stark. The disadvantage of using commas as parentheses is they can be easily confused with other commas in the sentence because — as you can see from this page — commas have lots of uses.

Read more about using commas to replace brackets.

(6) Using Commas in Lists

When writing a list in "sentence form" (i.e., not as bullet points), it is normal to separate the list items using commas. For example:

Fish, chips, and peas

The big question is whether there needs to be a comma before the conjunction (in this example, the word and). Unfortunately, there is no simple rule for this.

The first part of the rule is easy enough: when there are just two items in a list, there is no need to use a comma between them.

Fish and chips

However, you can use a comma if you think it helps your reader.

The Bakerloo Line runs between Harrow and Wealdstone, and Elephant and Castle.

When there are more than two list items in a list, then those following "US convention" should use a comma before the conjunction (usually and or or), and those following "UK convention" shouldn't. Therefore:

Fish, chips, and peas ()
Fish, chips and peas ()

Unfortunately, it gets a little more complicated than that. The comma before the conjunction is known as an Oxford Comma, and it is condoned by lots of individuals and organizations in the UK, and it is avoided by a few individuals and organizations in the US. Therefore:

Fish, chips, and peas () (This is correct if you're an advocate for the Oxford Comma.)

The bottom line is you should follow whatever convention those around you (e.g., your company seniors) follow. If there is no guidance like that, then follow whatever convention you like — but be consistent. If you have to break that convention for the sake of clarity, then have the confidence to do it. Clarity trumps style every single time.

Read more about using commas in lists.

(7) Using a Comma after a Long Subject

When the subject of a sentence is made up of lots of elements, it is known as a compound subject. For example:

Janet is popular.
Janet and John are popular.
The large gorilla is popular.
The large gorilla with the bright blue eyes and the albino lion cub with piercing pink eyes are popular.

In the last example, the compound subject is starting to get quite long. When a subject starts getting complicated, some writers like to show the end of the subject with a comma. Be aware that this is not a popular practice among many grammarians, but if you think it helps your reader, you can do it. For example:

Leaving a list of internet passwords, increasing your life insurance, and writing a will, will give you peace of mind while you are on operations.

will

(8) Using Commas in Numbers

Commas can be used every 3 digit positions in large numbers to make them more readable. For example:

3,356
12,128,153,356
175,757.01

In Europe, the use of commas and full stops (

) / periods (

) is reversed. So, in Europe, the numbers above would be written:

3.356 (in Europe)
12.128.153.356 (in Europe)
175.757,01 (in Europe)

(9) Using a Comma before Speech Marks

Words like He said, She shouted, The author stated, and She wrote often precede a quotation. A comma can be used after these words to separate them from the quotation. For example:

He said jokingly, "The world is my lobster."
Paul whispered, "Is he always that miserable?"

Note: You don't have to use a comma. Using nothing and using a colon after the words that introduce a quotation are also options.

In fact, it's your choice whether you follow your introductory words with a comma, a colon, or nothing. It depends on your desired flow of text. If you don't really care about the desired flow of text and you'd like some guidelines to help you decide which to use, then there is a useful guideline which states that a comma should be used for short quotations (six words or fewer) and colon should be used for longer quotations. (This is not a rule. It's a useful guideline.)

Read more about using a comma before speech marks.

(10) Using Commas with the Vocative Case

When words are used to address somebody (or something) directly, those words are said to be in the vocative case. In English, the vocative case is shown by offsetting it from the rest of the sentence with a comma (or commas if it's in the middle of the sentence). In the examples below, the words in the vocative case are shaded:

Do me the courtesy of shutting up, Alan.
Darling, can you take the casserole out the oven?
I know your sister, Jason.
Tell me it's good news, doctor.
And that, your Majesty, is how you make Eccles Cakes. I mean, it's how one makes Eccles Cakes.