Commas are easy to miss or erroneously add to a sentence, even if you are a native English speaker. Those who paid attention during their grammar classes in school are also not immune from making comma-related errors in their manuscripts. Moreover, different writing styles provide varied perspectives on comma usage, which only makes it trickier to get comma placements right.
A comma indicates a pause in a sentence. The presence of a comma ascertains where the pause begins and where it ends. Using a comma before or after a word, phrase, or clause depends on where you intend to have that pause in a given sentence.
There are multiple comma usage rules, and the factors determining their usage are not black and white. It takes a learned mind and a discerning eye to figure out when commas should go in a sentence and when they should be shunned. Keep reading to learn the basics of comma usage with different words.
What is a Comma?
A comma denotes a brief pause in a sentence. It’s a punctuation mark used to separate words, ideas, clauses, etc. in a sentence. Commas are required after dependent clauses and before coordinating conjunctions.
However, a comma not just creates a momentary pause in a sentence. A comma, when used right, lays the foundation for clear correspondence. Missing commas could sabotage a text or completely change a sentence’s meaning.
Here is a sentence with a comma, “We shall learn how to cut and insert, children.”
And this is the same sentence without the comma, “We shall learn how to cut and insert children.”
Looking at the sentences above, even those with rudimentary English knowledge would be able to discern how the second sentence’s meaning changes when the comma goes missing.
Commas, when needed, are critical to a sentence’s structure, meaning, and readability. There have been, in fact, instances of people losing money in the millions due to a missing comma.
Using Commas Before or After Words
A comma is commonly used in the middle of a sentence to separate two different clauses, right before the transition word. If a sentence is listing out things, multiple commas could be used. A comma is usually not placed after a conjunction or similar word, but there are instances when that could be the case.
Here is a massive list of various words and how commas can or should be used around them.
Comma Before or After “And”
A comma can be used before “and” if the conjunction links a couple of independent clauses. To understand how a comma works with “and”, you must know a few grammar rules – more specifically, an independent clause. An independent clause is essentially a part of a sentence that can be a sentence on its own. In other words, it comprises a subject and a verb.
Let’s understand the same with an example sentence: “She was walking, and she saw a duck”.
In this sentence, the conjunction “and” connects the two independent clauses. If the two clauses were separated to form their own sentences, they will still make meaningful, grammatically correct sentences. “She was walking.”; “She saw a duck.”
In the original sentence, alongside the conjunction “and”, a comma is also used to separate the two clauses.
A comma would not be needed if the sentence read something like, “She was walking and saw a duck.” It’s okay to not have a comma in this sentence as the second clause doesn’t have the subject “she” anymore.
What about placing a comma after “and”? Though not as common, putting a comma after “and” is not unheard of or even grammatically incorrect. A comma typically goes after “and” if the conjunction is followed by a conditional clause.
- The finance department found the missing thousand dollars and, unfortunately, we’ll have to terminate you.
- Tim walked into the city and, while being there, rode the metro.
Comma Before or After “But”
The rule for putting a comma before “but” can be quite tricky and easily overdone. The conjunction “but” should have a comma before it only if it’s linking two independent clauses – just like how it works with “and”. If not, you don’t need a comma.
Sentences with a comma before “but”:
- I want to become a professional playback singer, but I am not sure if I have the voice for it.
- I love her, but I am not ready for marriage.
A sentence without a comma before “but”:
- I left Kevin a message yesterday but have no response message yet.
In the above sentence, there is no comma before “but” as there is no subject before the second verb. Another example,
- Martha tried the new weight-loss diet but did not lose any weight.
As far as placing a comma after “but” is concerned, it’s usually not the norm like it’s the case with most conjunctions. When a sentence, however, begins with “But”, it could have a comma right after. For example,
- But, they were just too many.
When the conjunction “but” is used in the latter part of the sentence, it could have a comma right after only if the comma is parenthetical or used with another comma. For example,
- Arthur is a great athlete but, due to this injury, he couldn’t make it into the team.
Comma Before or After “Which”
Using a comma before “which” is a common practice. However, a comma before “which” is not always required and at times incorrect grammatically. A comma can be used before “which” if the phrase after it is nonrestrictive. A nonrestrictive clause offers supplemental or add-on information about the subject already discussed in the sentence.
- Adam’s new bike, which is only two months old, is having fuel economy issues.
The phrase “which is only two months old” is considered non-restrictive because removing it won’t change the sentence’s meaning.
- Adam’s new bike is having fuel economy issues.
If the phrase (is restrictive) adds a lot more value or could potentially wreck the sentence if taken out, a comma is not needed.
In fact, the word “which” will get replaced by “that”. For example,
- Smartphones that Rudolph purchases always go bust within a year.
If the restrictive phrase “that Rudolph purchases” were to be edited out, the sentence may not lose its structure, but it would certainly not mean the same thing. The sentence would then be talking about smartphones in general and not specifically Rudolph’s phones.
- Smartphones always go bust within a year.
Here are some more examples of sentences with “which” and a comma before the word:
- My father’s house, which sits in a posh locality, can do a fresh coat of paint.
- Harper’s latest YouTube video, which he spent a week filming and editing, is now trending on the platform.
- Everyone loved Mark’s new book, which he had been working on for the last two years.
A comma before “which” is not required if the word is a prepositional phrase. The following are examples of incorrect comma usage with “which”:
- They listened to four speeches, of, which one lasted for more than an hour.
- The package in, which the product arrived had no sender’s address.
The above sentences could do without the commas.
A comma can be used after “which” if the comma is paired with another comma or the sentence has a parenthetical phrase. For example,
- The party would take place in the dining hall which, for people who are not aware of, is in the first block.
In this sentence, the comma could also be used before “which”, but then you’ll have to get rid of the other comma. Here is the single comma version:
- The party would take place in the dining hall, which for people who are not aware of is in the first block.
Comma Before or After “Because”
The word “because” is typically used to connect two phrases in a sentence. A comma before the word is, therefore, not required. If no comma, however, leads to ambiguity, an exception can be made.
Here are example sentences demonstrating where to insert a comma or not use one around “because”:
- I like swimming and cycling because they are fun.
- I cannot cook my favorite meal because I don’t have all the ingredients I need.
- Stephen did not pass the test, because of his lack of preparation.
Sentences that usually have a comma before “because” are the ones that are in contrast with the initial part of the sentence.
In the third sentence above, if the comma is removed, it could imply that Stephen did not pass the test not because he didn’t prepare well but due to some other reason. With the comma in place, the relationship between him not clearing the test and his lack of preparation is clearly established.
Also, sentences with “because” don’t need a comma if the primary and secondary messages in a sentence are inseparable. If they could be proper sentences by themselves, a comma is needed to link the two.
A comma could be placed after “because” if the commas are in pairs or the phrase between the two commas can be eliminated without impacting the sentence – like it’s the case with comma usage after most other words on this list.
- After this monumental finding, everything looked unique because, one may ask, why a photon should at times be a photon in addition to being an electron-positron pair.
Comma Before or After “While”
A comma should not be used before “while” if the word is replacing the phrase “at the same time”. A comma, however, can be used after the conjunction if used as a replacement word for “although” or “whereas”.
When used as a conjunction, “while” could mean two things: one meaning relates to time, and another denotes a contrast.
The following are sentences in which not using a comma with “while” is correct:
- I worked so hard that I passed out on my desk while others were sleeping in their cozy beds.
- Buy the phone while it’s still up for grabs.
Using a comma with “while”:
- I like chocolate ice cream, while my wife is more into vanilla.
- The price of smartphones has been on the rise, while mobile data prices have been continually dipping.
When using “while” at the start of a sentence, you obviously don’t need a comma before it. But if “while” is used as an alternate word for “whereas”, you’ll have to insert a comma somewhere in the sentence, even if not in front of the word. For example,
- While my friends use iPhone, I am a hardcore Android fan.
The same sentence could be rephrased as:
- My friends use iPhone, whereas I am a hardcore Android fan.
A comma is almost never used after “while”.
Comma Before or After “Such As”
The phrase “such as” is used to introduce examples in a sentence. It doesn’t require a comma before it if the information used is a restrictive clause. If the added piece of information is nonrestrictive or not essential to the sentence’s meaning, a comma is required.
Here is an example:
- You’ll find different kinds of coniferous trees, such as spruce and pine, in this forest.
The phrase “spruce and pine” is nonrestrictive or taking it out would not affect the sentence’s meaning. “You’ll find different kinds of coniferous trees in this forest” still sounds correct without the non-essential phrase.
A comma must not be used with “such as” if it’s followed by a restrictive clause. For example,
- Trees such as elms and oaks do not grow at this height.
If you removed the phrase “such as elms and oaks”, the sentence would fail to convey what it originally intended to.
Basically, if the examples that follow “such as” are not integral components of the sentence, a comma is needed after “such as”. If the examples are essential, a comma is not needed.
Most importantly, there should never be a comma or any other punctuation after “such as”.
Comma Before or After “So”
The conjunction “so” is used to separate two different clauses in a sentence. A comma must be placed before “so” if the clause after it is an independent clause. A comma is not required if the clause is dependent or integral to the sentence. For example,
- The store had no 4K TVs, so I went to the other outlet.
- Martin brought in the maximum number of leads last month, so he was given two additional days off the next month.
Here are examples of sentences with the “so” conjunction, but without the comma, as there are no two independent clauses:
- He headed to the fish market so he could buy some fish.
- Mary worked hard so she could secure a promotion.
In these sentences, the phrases “so he could buy some fish” and “so she could secure a promotion” are not independent clauses or they cannot stand on their own as a single thought. If these phrases were used by themselves, the reader would want to know the preface or what happened before the sentences.
To be sure “so” in a sentence doesn’t require a comma before it, replace the conjunction with “therefore”, a conjunctive adverb. If “therefore” sits well with the sentence, you need a comma before “so”. If it doesn’t fit into the sentence, a comma before “so” is not required.
Incorrect and correct placements of “therefore” in the above sentences:
- The store had no 4K TVs; therefore, I went to the other store. (Correct)
- He headed to the fish market therefore he could buy some fish. (Incorrect)
Since “so” separates two independent clauses or suggests a change in the tone of a sentence, it only comes with a comma before it and not after.
However, when used in questions or at the starting of a sentence, the word “so” may have a comma after it. For example,
- So, are you going out with her?
- So, how did the interview go?
There are also instances when “so” may not be followed by a comma if it comes at the beginning of a sentence.
- So I heard that Tim is moving to Dallas.
Comma Before or After “Too”
Generally, a comma is used before “too” for emphasis or to indicate an unexpected shift in thought. The adverb could be placed in the middle or at the end of a sentence. For example,
- I, too, like pizza.
- I like burgers too.
- I will be coming, too.
That said, there is no binding rule as far as comma usage before “too” is concerned. As commas indicate a pause, particularly when ‘emphasis’ is meant, reading a sentence aloud and discerning if there’s a likely pause would help ascertain whether a comma goes with “too” in the sentence.
Both the sentences – one with the emphasis and the other without one – are correct:
- I, too, love spending time with you.
- I too love spending time with you.
Also, a comma can be placed after “too” only if the comma is in a pair.
The comma placement in this sentence is not correct:
- I too, love spending time with you.
Comma Before or After “Or”
When “or” separates two components, you need not use a comma with it. For example, comma usage in this sentence is incorrect,
- Would you like your martini stirred, or shaken?
It should be:
- Would you like your martini stirred or shaken?
Another example of incorrect comma usage before “or”,
- Do you like chocolate, or ice cream?
The correct sentence is:
- Do you like chocolate or ice cream?
If the sentence has three or more distinct elements, use commas to differentiate them. For example,
- The three popular ice cream flavors are vanilla, chocolate, and strawberry.
In some writing styles, the third comma – called the serial comma – may be missing. Therefore, the sentence could also be written as,
- The three popular ice cream flavors are vanilla, chocolate and strawberry.
The comma usage in both the sentences is correct. However, the inclusion of the third comma does make the first sentence look clinical and more readable.
Your sentences could either have or not have the serial comma. Whatever your approach, make sure you stay consistent or do not swing between the two – at least not in the same manuscript.
A comma usually doesn’t go after “or”. If you don’t want to put the comma before “or”, you will have to break the two clauses into two independent sentences, with a question mark separating the two. For example,
- Do you work from home? Or do you have an office set up somewhere?
Comma Before or After “Including”
The word “including” is used to introduce a phrase/clause or a non-exhaustive list of items. A comma is used before “including” when the word is followed by a non-essential, non-restrictive clause or phrase and can be separated from the first or primary part of the sentence.
Also, a comma or no comma before “including” could make or break a sentence. For example,
- I enjoy cooking Italian, including pasta.
- I enjoy cooking Italian including pasta.
In the first sentence, it’s clear the subject likes to cook Italian food, which includes making pasta. However, in the second sentence where there is no comma, the meaning changes completely. It indicates the subject likes to cook Italian food only if pasta is on the ingredients list.
A few more sentences where a comma is needed before “including”:
- The new rules apply to all, including the teaching staff.
- Most root vegetables, including parsnips and turnips, are high in vitamin C.
If “including” is at the beginning of a sentence, a comma is not required after it. For example,
- Including the iPhone 11 and the iPad Pro, I bought myself two new gadgets this year.
- Including myself, our office currently has 20 full-time employees.
Even when not the first word in a sentence, the word “including” may not have a comma before it. For example,
- The tablet sells for $600, not including the stylus.
- Was he including Tom into the team?
A comma is usually not placed right after “including”, like how a colon or semi-colon doesn’t go after the word.
Comma Before or After “As Well As”
The term “as well as” usually has no comma before it. In a sentence, it typically leads to fresh and necessary information that cannot be offset by a comma. For example,
- Kindly make us some boiled rice as well as fish curry.
The above sentence denotes a person is requesting another person to make them both boiled rice and fish curry. The words “as well as” are not defining the nouns prior to it or providing any information than can be left out.
If the information after “as well as” is non-essential or less important, a comma will be needed before the phrase. For example,
- Kindly make us some boiled rice and fish curry, as well as soup.
A comma is usually used before and also after “as well as” if the information is not vital to the sentence’s meaning and flow. For example,
- Marcus, as well as Terrence, is extremely particular about keeping the room clean.
In this sentence, if you take out the “as well as Terrence” part, the sentence will still read fine. Not to mention, putting commas with “as well as” takes the focus off Terrence.
Comma Before or After “However”
The conjunctive adverb “however” can be used in multiple ways, and its punctuation requirements will vary accordingly. The word “however” denotes the association between two contrasting independent clauses.
Here are sentences in which “however” has a comma before and/or after it:
- The doctors claimed that the patient was out of danger; however, they still recommended keeping her under observation for a couple of weeks.
- However, you should not have said that.
- I plan to continue in this office for one more year; however, she is leaving now.
- It is, however, very tough to decode them all.
The word “however” usually has a semicolon before it if the phrase following it is an independent clause. If “however” is used as an interruption in a sentence, a comma usually goes before it.
Kindly note “however” is a strong transition word. Not using a comma before and/or after it could cause ambiguity.
Comma Before or After “Since”
The conjunction “since” could be used in multiple ways. The word usually doesn’t require a comma if it plays the role of a preposition. For example,
- I have not seen him since 2015.
- She has been much happier ever since she moved out of that city.
- We last met a couple of years ago, and she has only become bitterer since.
At times, “since” could be used instead of “because” and it may not need a comma even then. For example,
- Jim purchased more socks since he was losing them regularly.
- The theater company had to stall its production work since it was lacking funding.
If the phrase after “since” is a negative phrase, a comma is required before it. For example,
- Paula couldn’t go for the interview, since she had to go to the hospital.
You could replace “since” with “because” in the last two sentences above. Not to mention, “since” is more formal than “because”.
It is not common practice to follow up “since” with a comma, however.
Comma Before or After “Who”
The pronoun “who” is interrogative and invariably denotes humans. It could be used to seek information about an individual or could also begin a clause that provides extra information about someone. A comma usually doesn’t go before “who”. If there is one, it is most likely parenthetical. In other words, the phrase accompanying “who” is an independent clause. For example,
- My eldest daughter, who just turned nine, is a child prodigy.
In this sentence, the phrase “who just turned nine” could be removed without affecting the sentence’s grammar or readability.
If the phrase after “who” is a restrictive clause, a comma should not be used. For example,
- I admire students who work hard throughout the year.
Since there is no comma in the sentence, it clearly means the subject likes students who work hard throughout an academic year.
If there happened to be a comma, it would indicate the phrase after who is non-restrictive or not important to the sentence. The phrase before “who”, after the non-essential information is taken out, would turn into an ambiguous statement. In other words, “I admire students” would sound incomplete.
Talking about commas right after “who”, they are usually not or almost never used.
Comma Before or After a “Quotation”
There must always be a comma before or after a quote. If a sentence starts with the quote, the comma will be after the quote. If a sentence ends with a quote, there must be a comma before the quote. Also, if the attribution is prior to the quote, the comma should be outside the quote. For example,
- Jim said, “I ate ice cream.”
If the attribution is after the quote, the comma should be within the quote:
- “I ate ice cream,” said Jim.
Placing a comma after or outside a quote is incorrect, as per American English writing guides.
- “I’ll be there tomorrow”, said Alex (incorrect)
- “I’ll be there tomorrow,” said Alex (correct)
In UK English, however, it’s not wrong to have the comma after and outside a quote. The Associated Press (AP), The Chicago Manual of Style, and Modern Language Association (MLA) go with the American rule. Therefore, if you are not specifically catering to UK readers, it’s recommended you keep your commas inside the quote.
Comma Before or After “Where”
“Where” is an interrogative word. It’s accompanied by a comma based on how it’s used or where it goes in a sentence. In other words, if the phrase or words after “where” represent a non-restrictive clause or offer additional information that could be edited out, a comma becomes mandatory.
The following are sentences with and without a comma before “where”:
- I would like to move to New York where there are business opportunities galore.
- I have no clue where we are.
- We headed to the other restaurant, where she found her ex on a date with another girl.
If “where” is used at the beginning, like in a question, a comma is not needed. For example,
- Where do you come from?
- Where could I find authentic Japanese food?
- Where were you yesterday?
A comma is pretty much never used after “where” – whether it is in the beginning, middle, or end of a sentence. However, if it’s a part of a quote and the quoted sentence ends with “where”, you could have a comma after the word. For example,
- “I am not certain where,” he lied.
Comma Before or After “Then”
The word “then” can possibly have a comma before and/or after it or have no comma at all. It is common practice to use a comma before “then” if the sentence starts with the word “If”. For example,
- If I were to use proper punctuation, then I would be generous with my comma usage.
- If God can hear my prayers, then he will grant my wish.
- If you don’t eat your vegetables, then you will not grow strong.
A sentence with a “then” and a comma before it invariably has the “If” hypothesis. But if there is “and” instead of a comma, the sentence is unlikely to be an “If-then” type sentence. For example,
- He muttered something and then drove away.
- Jonathan glanced at Patrick and then slapped him right away.
Kindly note, an “If-then” sentence may not have “then” in it and still be fine. For example,
- If God could hear my prayers, he will grant my wish.
- If you don’t eat your veggies, you will not grow strong.
The word “then” can also have a comma after it in a sentence. For example,
- Since then, she has been more careful.
Comma Before or After “Though”
The word “though” is a conjunction typically used in place of words such as “however” and “moreover”. It usually has commas on its sides if it’s all by itself somewhere in the middle of a sentence. For example,
- I think she knew, though, that he was not coming back.
Here are a couple of sentences in which the word has a comma before it:
- I didn’t really get your point, though.
- She was leaning against the gate, though.
When a sentence starts with “Though”, there is no comma anywhere close to the word. Here is an example sentence:
- Though she studied hard, she couldn’t pass the exam.
A comma is also usually not needed before “though” if a sentence ends with the word. For example,
- I am not sure how relevant it is in today’s times though.
However, when reading the sentence aloud, the word “though” could indicate a brief pause. Therefore, the same sentence could also have a comma.
- I am not sure how relevant it is in today’s times, though.
It is not incorrect either way, but if not using a comma feels correct, go ahead and leave it out.
Learning English, particularly the grammar part, is a work-in-progress. The key to not making mistakes with commas is not just religiously conforming to the rulebook, but also being able to answer the question, “What is a comma doing in that sentence?”. If you could answer that question every time you use a comma, the punctuation would start making more sense.
Commas were used more extensively in olden texts, particularly in novels from the Victorian era. Modern literature, however, has gravitated toward using the comma and other forms of punctuation less often. Punctuation styles have evolved, to say the least.
If you feel a sentence could do without a comma, you need not put one in. But if the absence of a comma changes the meaning of a sentence or the sentence just doesn’t read and look right anymore, please use a comma.