Comma

In the early 1990s, at school in Oxford, England, my English teacher tried to teach us how to use commas. I remember it so well because of the feeling of utter bamboozlement that overcame me. In an attempt to simplify the complex rules of comma punctuation placement, my teacher used the rough-and-ready rule of "you should use a comma where you would pause in speaking". In retrospect, I think this just confused me more. I'm sure many people have felt the same way.

Commas are one of the most frustrating grammatical concepts, even for native English speakers. Nevertheless, there are specific rules for when you should and shouldn't use commas. Building our grammar checker we've identified 26 places where you might need a comma. In this article, I will explain all of these places along with examples of how to use commas in English sentences. Just bookmark this article in case you ever get confused by a comma again.

You'll see lots of articles named things like "13 Rules for Using Commas" or "8 Simple Comma Rules". The reality is that there are many more rules for using commas. Don't despair though. Unlike many rules in English, they actually make sense, as they are designed to help avoid confusion. Missing commas can have a HUGE impact on the meaning of your sentence. Missing commas can even cost a million dollars.

To produce this list, our team of linguists analyzed thousands of sentences and classified every comma in each sentence according to its use. They also found MANY mistakes as well. We used all of this data to build our list and to train the automated comma checker in our free grammar checker. All the information below is built into our grammar checker so that every time you make a mistake you can see why.

So, where do commas go in a sentence? This is the definitive list:

• Before a coordinating conjunction when it separates two independent clauses.

• Before "then" when it separates two independent clauses.

• Before a coordinating conjunction when it separates an independent and dependent clause as an Oxford comma.

• After an initial/introductory adverb that modifies a whole sentence or independent clause.

• After a time phrase that comes before a sentence or independent clause.

• After a subordinate clause—one that starts with a subordinating conjunction.

• Before a subordinate clause—in some specific cases.

• Between two adjectives when they both modify the noun—coordinate adjectives.

• After an introductory prepositional phrase.

• Before and after a participle phrase.

• When a word is omitted intentionally for stylistic reasons.

• After an adverbial infinitive phrase.

• At the end of a quotation, before the closing quotation mark.

• Before an opening quotation mark.

• To set off contrasting phrases.

• Before an appositive.

• After an appositive.

• Before "which" in nonrestrictive phrases.

• To separate list items.

• To separate out a parenthetical element of a sentence.

• To separate city and country/city and state.

• To set off a vocative.

• To separate the day from the month, and the date from the year.

• Before and after "too."

• In numbers as a separator.

• Before and after “please.”

• Before and after "then."

That’s a long list, and it requires some knowledge of grammatical terminology to process it. So let’s look at specific questions and examples of comma usage.

Is it grammatically correct to put a comma before "and"?

It is grammatically correct to use a comma before "and" (and other coordinating conjunctions such as "but", "or", "nor") only when it splits two independent clauses (i.e. if you remove the "and" you will be left with two complete sentences), or if you're using it as an Oxford comma.

There are three ways that "and" can be used in a sentence: - To separate two independent clauses, i.e. you should be able to remove the "and" and be left with two complete sentences. - To separate two dependent clauses, i.e. if you took the "and" away then you wouldn't have two sentences. - To separate items in a list, e.g. buckets and spades, or lions and tigers and bears. A comma is used before an "and" only if it is used to separate two independent clauses, or if it is used as an Oxford comma to separate the last item in a list of three or more things.

Correct: He is great, and I admire him.

In this case there are two independent clauses as I could write: "He is great." and "I admire him."

If both the independent clauses are short then some writers may choose to omit the comma before the "and", but you will never be wrong to use it. So if you're not sure then I advise you to include it.

If I wrote instead: "He is great and works hard," this is an independent clause and a dependent clause, because "works hard" is not a complete sentence.

Correct: He is great and works hard. Incorrect: He is great, and works hard.

In some circumstances, you may use a comma before a conjunction such as "and" when it starts a dependent clause. This is when you are using the comma as an Oxford comma (sometimes known as a serial comma). The conjunction must split the third item of a list. e.g. I ate, slept, and dreamed of England.

Read more about using an Oxford comma.

Correct: He ate dinner, slept all night, and awoke refreshed. (as an Oxford comma) Incorrect: He ate dinner, and awoke refreshed. (not an Oxford comma)

Is it grammatically correct to put a comma before "then"?

The word "then" can function as several parts of speech. For comma usage, the most important usage is as a conjunction. In theory, "then" is not a coordinating conjunction (like "and", "or"), but sometimes it is used as such.

Example: I went to bed, then I started dreaming.

Here, "then" is used as a shortened form of "and then". Some people might strongly disagree with this sort of sentence, but the truth is that it is widely used, even by The New York Times.

You can read more in this article.

We recommend that where "then" can be replaced by "and then" you use the same rules for comma placement as adding a comma before an "and", i.e. add one if the following phrase is an independent clause.

Should I use a comma after an introductory adverb like "apparently"?

Adverbs are words that modify verbs or even whole sentences. They often end in "-ly". Examples include "quickly", "frequently", "slowly". You can see that they "add" some information to a "verb" or the sentence that they are modifying. Some adverbs don't end "-ly", e.g. "sometimes" or "often".

When an adverb modifies an entire sentence or independent clause that follows it then you should use a comma after it.

Correct: Sadly, they didn't understand me.

Incorrect: Sadly they didn't understand me.

Correct: Strangely, the book hasn't arrived.

Incorrect: Strangely the book hasn't arrived.

So when "apparently" modifies the whole sentence or clause that follows it then it should be followed by a comma.

Correct: Apparently, he doesn't have a clue.

Incorrect: Apparently he doesn't have a clue.

Should I use a comma after a time phrase such as "in the meantime"?

A time phrase is something that gives details of the time that something happened. It might be a single word or a complete phrase. Some examples of time phrases are tomorrow, at 2pm, five hundred years ago, and in the meantime.

When a time phrase adds information to an independent clause or sentence that follows it then it should be followed by a comma. If the phrase or sentence comes before the time phrase then it shouldn't have a comma before it.

Correct: Five hundred years ago, there were no grammar books.

Incorrect: Five hundred years ago there were no grammar books.

Correct: There were no grammar books five hundred years ago.

Incorrect: There were no grammar books, five hundred years ago.

Correct: Yesterday, there was no new news.

Incorrect: Yesterday there was no new news.

Correct: There was no new news yesterday.

Incorrect: There was no new news, yesterday.

How should I use a comma with a subordinate clause?

Subordinate clauses are sentence fragments that start with a subordinating conjunction (e.g. after, although, as, as if, as long as). They can't form a sentence on their own, but they add information to the main clause, usually some form of condition, e.g. if you do this, whenever you see him.

Subordinate clauses are great because they add variety to your writing, but often, writers are not sure how to use commas with them. A missed comma after a subordinate clause is one of the most common mistakes that we see. So how do you punctuate a subordinate clause? It turns out there is a pretty simple rule:

If a subordinate clause comes before the clause it is attached to then it should be followed by a comma. You do not need a comma before a subordinate clause if it follows the main clause (except "whereas" and "although").

Correct: If you're ready, we can begin.

Correct: We can begin if you're ready.

Incorrect: If you're ready we can begin.

Incorrect: We can begin, if you're ready.

Correct: Although you're ready, we must wait.

Correct: We must wait although you're ready.

Incorrect: Although you're ready we must wait.

Incorrect: We must wait, although you're ready.

Should you use a comma before "whereas" and "although"?

The words "whereas" and "although" are subordinating conjunctions. The general rule for subordinating conjunctions states that you shouldn't use a comma before a subordinating conjunction that comes after the main clause. However, "whereas" and "although" are examples of "adverbs of concession," along with "though" and "even though". They are used where a dependent clause is contrasting to the main clause (a bit like "but"). You should use a comma to introduce a dependent clause that starts with an adverb of concession.

Correct: I waited at the door, whereas Katy waited in the street.

Incorrect: I waited at the door whereas Katy waited in the street.

Should you use a comma before "while"?

Slightly more complex is the question of whether you should use a comma before "while." While is a subordinating conjunction, but in some circumstances it can act as an adverb of concession as well. In these circumstances it should have a comma before it.

If you can replace while with as, then it shouldn't have a comma before it. It is just a normal subordinating conjunction. If you can replace while with whereas then you should use a comma before it because it is being used as an adverb of concession.

Correct: The man left the restaurant while [as] it was raining.

Incorrect: The man left the restaurant, while [as] it was raining.

Correct: The man left the restaurant, while [whereas] his partner stayed.

Incorrect: The man left the restaurant while [whereas] his partner stayed.

Should you have a comma before "because"?

In most circumstances, "because" is a subordinating conjunction, so when it starts a dependent clause after the main clause, it shoudn't be preceded by a comma. However, there are two exceptions to this rule:

• when the independent clause that comes before "because" contains a negative verb (e.g. don't, couldn't, wouldn't)
• when the independent clause that comes before "because" contains two elements and it is unclear which one "because" refers to.

Let’s look at an example of when the independent clause that comes before "because" contains a negative verb:

He didn't take the exit because of the fog.

This example is confusing because you're unsure whether it was the fog that caused him to miss the exit, or some unknown factor. e.g. He didn't take the exit because of the fog, but because he wasn't paying attention.

Where you mean that the fog didn't cause him to miss the exit it might be best to rewrite it as: The fog didn't cause him to miss the exit. If you mean that he missed the exit because of the fog, then you should include a comma.

Correct: He didn't take the exit, because of the fog.

Incorrect: He didn't take the exit because of the fog. (ambiguous)

Correct: I couldn't come, because of the traffic.

Incorrect: I couldn't come because of the traffic. (ambiguous)

Correct: I couldn't come because of the traffic, but because my car broke down.

Correct: It wasn't the traffic that meant I couldn't come, it was because my car broke down.

Let’s look at an example of when there are two elements in the independent clause that precede “because” and the dependent clause could refer to either one.

I thought you sent me flowers because I saw you yesterday.

Did you send me flowers because you saw me yesterday, or did I think you sent me flowers because I saw you yesterday and you hinted you might?

As a side note, these kinds of ambiguous constructions are best avoided. Rewrite them to be unambiguous. Any sentence that cause ambiguity in your readers' minds stops them understanding your message.

Should I use a comma before "for"?

In some circumstances, "for" can be replaced with "because". In that case then it follows the rules for "because" outlined above, i.e. only include a comma before "for" when the verb in the independent clause that precedes it is negated and this might cause confusion.

Should I use a comma before "since"?

In some circumstances, "since" can be replaced with "because". In that case then it follows the rules for "because" outlined above, i.e. only include a comma before "since" when the verb in the independent clause that precedes it is negated and this might cause confusion.

Should I use a comma between two adjectives?

Adjectives are words that modify a noun to add more detail, for example: "old", "red", "greasy". They should really be called "adnouns" to be consistent with "adverbs." Sadly, they're not, but that's a good way to think of them.

You should use a comma between two adjectives when they are coordinate adjectives. Coordinate adjectives are two or more adjectives that describe the same noun equally.

With coordinate adjectives you can put "and" between them and the meaning is the same. Similarly, you can swap their order.

For example: The long, metal pole. "Long" and "metal" are both adjectives that describe the noun "pole": I could write "long pole" or "metal pole". I could also write "long and metal pole" and "metal and long pole" and "metal, long pole". They might sound slightly strange but the meaning is retained.

Cumulative adjectives build on each other and cannot be re-ordered or split with "and," for example: bright yellow jacket. It can't be "bright and yellow jacket" or "yellow bright jacket".

Because coordinate adjectives are equally important, they are separated by a comma. Cumulative adjectives aren't equally important and so they are not separated by a comma. Only use a comma to separate two adjectives if you could also write "and" there and keep the same meaning.

Correct: The long, metal pole stuck out of the ground.

Incorrect: The long metal pole stuck out of the ground.

Correct: The bright yellow jacket looked amazing.

Incorrect: The bright, yellow jacket looked amazing.

Do you always put a comma after a prepositional phrase?

An introductory prepositional phrase sets the scene for the main phrase. It is often to do with time or location, e.g. In the morning or In 2018. An introductory prepositional phrase starts with a preposition (words like in, on, after, before).

For short introductory phrases (fewer than four words), you can choose to add a comma or not. For longer phrases, you should always use a comma.

Short prepositional phrase:

Correct: In the morning let’s go to the zoo.

Correct: In the morning, let’s go to the zoo.

Longer phrase:

Correct: On the morning of his birthday, Robbie wanted to go to the zoo.

Incorrect: On the morning of his birthday Robbie wanted to go to the zoo.

Note: you might also find these prepositional phrases in the middle of sentences after a conjunction, e.g. He went to bed, and in the morning, he wanted to go to the zoo. For these, you should follow the same rules as if they came at the beginning of a sentence.

Should I use a comma with a participle or gerund phrase?

Participle phrases are phrases that modify a noun or pronoun. They add extra context. Here are a couple of examples:

Example: Walking to the shops, he saw his cousin.

Example: Upset by his cousin, he went home.

Example: Frank, hoping to get promoted, applied for the role.

Example: Anne applied for the role, hoping to get promoted.

Example: Katy walked home, tired from a hard day in the office.

The two forms of participle phrase you can see here are:

• Present participle (always ending -ing), e.g. walking, hoping.

• Past participles (often ending -ed, but sometimes irregular), e.g. tired, upset.

Note: sometimes participle phrases can be disguised if there is an adverb on the front, e.g. Desperately seeking shelter, he ran into the building.

The comma rules you need to know for participle phrases are:

• For participial phrases before the main clause, put a comma after the participial phrase.

• For participial phrases in the middle of the sentence, the phrase requires commas both before and after it.

• For participial phrases after the main clause, put a comma before the participial phrase.

Do I need a comma when I omit a word for stylistic reasons?

Sometimes when writing we omit words for stylistic reasons. This comma of omission is often seen when parallel structures are used, such as two sentences taking the same form.

Example: I loved playing tennis; my brother [loved] volleyball.

Correct: I loved playing tennis; my brother, volleyball.

Incorrect: I loved playing tennis; my brother volleyball.

We also need to include a comma of omission when we have removed a coordinating conjunction (usually "and"). This construction is fairly rare.

Example: I opened the boot [and] saw the spare tyre.

Correct: I opened the boot, saw the spare tyre. Incorrect: I opened the boot saw the spare tyre.

Correct: Carrie mimicked his tilted head, [and] then laughed.

Incorrect: Carrie mimicked his tilted head [and] then laughed.

Do you need a comma after an adverbial infinitive phrase?

Infinitive phrases begin with an infinitive (to + the simple form of the verb), e.g. to be better, to win at tennis, to save money.

Infinitive phrases can function in a sentence as nouns, adjectives or adverbs. From a comma perspective you only need to worry about ones that function as adverbs. These are often found at the start of a sentence, but are not the subject.

Example: To be the best, you must practice.

Example: To read more, please subscribe to our newsletter.

When an adverbial infinitive phrase introduces a main clause then you should always follow it by a comma:

Correct: To be the best, you must practice. Incorrect: To be the best you must practice.

But be careful that the phrase is not acting as a noun. Never put a comma after an adverbial phrase when "is" or "was" directly follows:

Correct: To be the best is his goal.

Incorrect: To be the best, is his goal.

When an adverbial infinitive phrase is found in the middle of a sentence you should surround it with commas. In this case, it is acting as an interrupter:

Correct: The suit, to be fair, suited him.

Incorrect: The suit to be fair suited him.

Incorrect: The suit, to be fair suited him.

Incorrect: The suit to be fair, suited him.

When an adverbial infinitive phrase finishes a main clause then you shouldn't use a comma before it:

Correct: The suit suited him to be fair.

Incorrect: The suit suited him, to be fair.

Should I use a comma at the end of a quotation, before the closing quotation mark?

In American English, you should always place a comma or period inside quotation marks. In UK usage, you can choose. Most style guides, such as the Modern Language Association (MLA), Associated Press (AP), and The Chicago Manual of Style (Chicago) suggest the American rule. If you're uncertain who your audience will be then it's best to always place your commas inside of quotes. That way you'll never been seen as wrong.

Correct: "I'll come along later," said Mary.

Incorrect in US: "I'll come along later", said Mary.

Incorrect in US: "I'll come along later" said Mary.

Should I use a comma before an opening quotation mark?

When you include quoted material or dialogue in a sentence then you should proceed it with a comma unless it fits into the flow of the sentence seamlessly, e.g. The President said that there is "no smoking gun" to be found.

In these cases, the sentence would be syntactically correct without the quotation marks, and you are just using the quotation marks to show that the quote is a direct quote. Often, in this scenario, the quote will be preceded by "that", e.g. He said that "the country will continue to grow."

Otherwise, you should use a comma before opening quotation marks, e.g. Sandra called out, “What do you want from the store?”

Should I use a comma before "which"?

To understand if you should use a comma before which we need to understand the difference between a restrictive and a non-restrictive clause.

A restrictive clause is one where its removal would alter the meaning of the sentence. It is necessary for understanding the meaning of the sentence. In the US, many style guides suggest that you should use "that" rather than "which" for restrictive clauses, e.g. The fruit that we bought was tasty.

A non-restrictive clause does not alter the meaning of the sentence. This additional information is used with “which” and a pair of commas placed before and after the clause:

Correct: The fruit, which everyone found tasty, was my best idea.

Incorrect: The fruit which everyone found tasty was my best idea.

Incorrect: The fruit, which everyone found tasty was my best idea.

Incorrect: The fruit which everyone found tasty, was my best idea.

"Which" can also appear as part of a prepositional phrase, e.g. The team in which we played was great. When "which" appears in a prepositional phrase, it should not be preceded by a comma. Other examples of which in a prepositional phrase are "on which" and "of which."

Correct: The games, the longest of which lasted two hours, were fun.

Incorrect: The games, the longest of, which lasted two hours, were fun.

Correct: The situation in which we found ourselves was fun.

Incorrect: The situation in, which we found ourselves was fun.

Should you use a comma before "which" in an indirect question?

When you're using "which" at the start of an indirect question, it should be preceded by a comma.

Correct: I asked, which is the best?

Incorrect: I asked which is the best?

This is similar to the rule about using a comma before a quotation as you can imagine the indirect question being surrounded by quotation marks.

Should I use a comma before and after an appositive?

An appositive is a word or phrase that helps to further identify a noun. Often the appositive can be swapped with the noun it helps describe.

Example 1: Manuel Picon, the former French President, visited the UK yesterday.

Example 2: The former French President Manuel Picon visited the UK yesterday.

Notice that in the first example, we use commas around the appositive, but in the second example we don't. That's the trick here. If the appositive is essential to the meaning of the phrase then we don't have commas, i.e. in Example 2 if we remove "Manuel Picon" we don't know which former French President we're talking about. In Example 1, we know exactly who visited the UK, so we add commas around the appositive because it is non-essential.

In some cases it can be tricky to decide. For example, if I say: My sister, Mary, will come then I may or may not use commas depending on the context. If I have several sisters and it is unclear which one will come without the appositive then I should not use commas. If I have only one sister then I should use commas. Just consider whether the meaning is unclear if the appositive is removed and if it is then don't use commas.

Should I use a comma before "not"?

Commas are often used to set off a contrasting element in a sentence. These contrasting elements often start with "not": e.g. He chose the green, not the red., It happened at night, not during the day.

When not starts a contrasting phrase then you should proceed it with a comma.

Not can also be used as a simple adjective. In this case, you wouldn't use a comma before not: e.g. He is not happy., She is not going to come.

Should I use a comma before "yet"?

Yet can be used to start a contrasting element in a sentence, e.g. She was sad, yet relieved.

When yet is used to set off a contrasting element of a sentence then it should have a comma before it, just like with not.

Other examples of contrastive elements that should be preceded with a comma are:

You're coming, aren't you?

The statue seemed different, almost alive.

The politician seemed stupid, possibly even moronic.

This last example shows that sometimes contrasting elements can be disguised with an adverb before them. So sometimes you might have to look at the second word of a contrasting element to decide whether or not it needs to be proceeded with a comma.

Do I need to use a comma with list items?

When we have a list of three or more items, we use a comma to split the items in the list. This comma is known as a listing comma, e.g. I like rice, beans, and plantains. Listing commas can usually be replaced by "and" or "or," e.g. I like rice and beans and plantains.

Listing commas can separate lists of nouns, verbs, adjectives, dependent clauses, or even complete sentences. This can mean that you can have a comma before an "and" that is followed by a dependent clause if it is the last item in a list of dependent clauses. Some authors like to join sentences with listing commas, e.g. I came in, I saw the package, and I opened it.

When using listing commas, the comma before the final "and" or "or" is optional depending on if you are using Oxford commas or not. How to use an Oxford (or serial) comma.

How do I use commas with parenthetical elements?

A parenthetical element is an element of a sentence that is added but is not essential to the meaning of the sentence. It adds color to the sentence, e.g. Of all the chilli sauces I’ve tried, and I’ve tried a lot, this is my favourite. or Some people, who I won’t name, wouldn’t like this.

Normally a parenthetical element has a comma before and after it. Instead, you might choose to use brackets or dashes to separate a parenthetical element from the rest of the sentence.

Here are some examples of parenthetical items used correctly with commas:

• Maria, although she comes from Spain, hates paella.

• This is, in my opinion, the most important issue.

• The biggest issue, as you will see, is where we will store all the extra components.

• The holidays in Spain, of which there are many, are mostly religious.

Interjections such as “yes” and “no” are generally treated as parenthetical elements. When they come at the start of a sentence, they should be followed by a comma. When they come at the end of a sentence, they should be preceded by a comma.

Should I use a comma between a city and a country/a city and a state?

In geographical names with two or more elements, you should use a comma after each different element. This helps the reader to see the different component parts of the address. You should also use a comma after the last item in the name unless it comes at the end of the sentence in which case you should use a period (or question mark if it is a question). e.g. Is Oxford, England, full of clever people?

The main times when geographical names are composed of two or more entities are:

• between a village/town/city and a state, e.g. I live in Miami, Florida.

• between a village/town/city and a country, e.g. I live in Liverpool, England.

• between a county and a state, e.g. I live in Cook County, Illinois.

• between a county and a country, e.g. I live in Cornwall, England.

• between a village/town/city and a region, e.g. I live in Garsington, Oxfordshire.

• between a region and a country, e.g. I live in Tabasco, Mexico.

A classic example would be if you used an address in a piece of text, e.g. Eric Wimp, living at 29 Acacia Road, Nuttytown, eats a banana to transform into Bananaman.

The parts of an address should be separated by commas and it should be followed by a comma unless it appears at the end of a sentence.

Should I use a comma before and after vocative?

A vocative is when you use address someone by name, e.g. Pass the salt, Mary. or Are you a prince, Harry? or Meg, are you there?

Vocatives are usually found at the beginning or the end of a sentence, but they can be included in the middle of a sentence, e.g. What, Harry, is your title?

Vocatives should always be used with commas. Here are the three rules for using commas with vocatives:

• use a comma after a vocative at the start of the sentence.

• use a comma before a vocative at the end of the sentence.

• use a comma before and after a vocative in the middle of the sentence.

Correct: What is that, Frank?

Incorrect: What is that Frank?

Correct: Frank, what is that?

Incorrect: Frank what is that?

Correct: What, Frank, is that?

Incorrect: What Frank is that?

Incorrect: What, Frank is that?

Incorrect: What Frank, is that?

In some cases you might not use someone's name to refer to them, but a title, or other description. Some examples of this are: sir, madam, boy, darling, sweetheart, pal, gentlemen, folks. e.g. It's great to see you here today, folks.

When using a vocative in the middle of a sentence, make sure that you're not actually creating a comma splice by joining two independent clauses.

Correct: This is great, Joe. I love it.

Incorrect: This is great, Joe, I love it.

Correct: We love it, Louise. We'll use it.

Incorrect: We love it, Louise, we'll use it.

Do you need a comma to separate the day from the month, and the date from the year?

When you write a date, you should use a comma to separate the day from the month, and the date from the year, e.g. He was born on October 8, 1977. or Today is Tuesday, August 8, 2019.

Correct: I was born on Saturday, October 8, 1977.

Incorrect: I was born on Saturday October 8, 1977.

Incorrect: I was born on Saturday October 8 1977.

Incorrect: I was born on Saturday, October 8 1977.

If you put the day of the month first, e.g. 12 May 2012, then there is no need to include commas in the date.

Do you need a comma before or after "too"?

Too is an adverb. It's usually used to mean "in addition" or "also." I would say that "too" is one of the hardest words to know whether you should use a comma or not. It really depends and many editors will have contradictory views. On the other hand, you could say that's great news as you'll never be wrong. If you want to emphasize the "too" then use a comma, but if it's not that important then you can get away with leaving them out.

If "too" comes in the middle of a sentence then you should either have two commas or no commas. If you just have a single comma before or after then that's definitely wrong.

Correct: I, too, like being with you. (emphasis)

Correct: I too like being with you. (no emphasis)

Incorrect: I too, like being with you.

Incorrect: I, too like being with you.

Correct: I like you, too. (emphasis)

Correct: I like you too. (no emphasis)

When should I use a comma to separate numbers?

In English, we use commas in numbers greater than 999 to split the number and make it clearer. We use a comma every third digit from the right.

Incorrect: More than 50000 people turned up to protest. Correct: More than 50,000 people turned up to protest.

Note how much easier it is to read. The comma every third digit is sometimes known as a “thousands-separator.” Make sure you don’t include a space on either side of this comma.

Correct: We will walk 10,000 miles.

Incorrect: We will walk 10, 000 miles.

Incorrect: We will walk 10 , 000 miles.

Incorrect: We will walk 10 ,000 miles.

When a number uses a decimal point, we never place commas to the right of the decimal point. Some people like to use thin spaces going from left to right instead.

Correct: The value of Pi is 3.14159 to five decimal places.

Correct: The value of Pi is 3.14 159 to five decimal places.

Incorrect: The value of Pi is 3.141,59 to five decimal places.

Incorrect: The value of Pi is 3.14,159 to five decimal places.

Numbers that are not amounts, such as phone numbers, house numbers, and years do not usually have commas inside them.

It can get confusing as many other countries (such as Spain) use commas in numbers instead of a decimal point, e.g. 100,01 instead of 100.01. In these cases, you might see a period used instead of commas or a space, e.g. 1.000,01 or 1 000,01 instead of 1,000.01.

Should I use a comma before or after “please” in a sentence?

If please comes at the end of a sentence then you should almost always use a comma before it. The only exception is when you are not using it to ask nicely, but as part of the sentence, e.g. You can do as you please.

Correct: Can you help, please?

Incorrect: Can you help please?

Correct: Do as you please.

Incorrect: Do as you, please.

When please is used at the start of a sentence then you can choose to use a comma depending on if you’d like to emphasize it.

Correct: Please, can you help? (emphasis)

Correct: Please can you help? (no emphasis)

Please can appear in the middle of a sentence. This is quite unusual. It might appear as:

• part of a phrase no commas needed, e.g. Don’t forget to say please and thank you.
• as a verb with no commas needed, e.g. He wants to please us.
• after a conjunction or at the start of a clause where you should use a comma after it if you want to emphasize it, e.g. You can go, but please, be careful. or If you go, please be careful.

When is a comma unnecessary?

Many people use a comma where they would pause naturally in a sentence. While this simple trick often works, you often end up adding a comma where it is not necessary. Adding unnecessary commas into a sentence can clutter it and make it less readable. Here is some more specific guidance on when you don't need to use a comma:

Should you follow an introductory phrase with a comma?

When should you use a comma before a coordinating conjunction?

Do I need a comma after a subordinate clause?

Do I need a comma after a participle phrase?

To avoid using unnecessary commas, make sure that you are familiar with all the rules in this article.

Have we missed anything? We’ve tried to build an exhaustive list of every possible case where you might need a comma. Please let us know if you can think of anything else.

Please link to this resource from your blog or web page so we can help as many people as possible understand commas.