Common Comma Mistakes
Summary
Avoid making these 12 common comma mistakes.
1. Don’t use a comma to join two sentences.
- Incorrect:I looked for him everywhere, he was gone.
Correct:I looked for him everywhere. He was gone.
2. Don’t unnecessarily insert a comma after a verb.
- Incorrect:Lulu laughed, when she heard the story.
Correct:Lulu laughed when she heard the story.
3. In long sentences, it’s easy to mistakenly place a comma before a verb.
- Incorrect:What Farley believed to be true, was in fact a lie.
Correct:What Farley believed to be true was in fact a lie.
4. A comma usually isn’t needed after a conjunction.
- Incorrect:The match was called off because, it was raining.
Correct:The match was called off because it was raining.
5. When you’re reporting something, don’t use a comma after that.
- Incorrect:Maya wished that, she were a cat.
Correct:Maya wished that she were a cat.
6. Essential phrases and clauses aren’t enclosed in commas.
- Incorrect:The researcher, who discovers a cure for laziness, will win the Nobel.
Correct:The researcher who discovers a cure for laziness will win the Nobel.
7. Adjectives that build upon each other in a sentence (and can’t be joined by and) don’t take commas.
- Incorrect:We had some tasty, Italian food last night.
Correct:We had some tasty Italian food last night.
8. Use commas to set off interjections.
- Incorrect:Man cheese makes everything taste better.
Correct:Man, cheese makes everything taste better.
9. Don’t forget the commas in a list.
- Incorrect:Lulu loves baking her husband and her cats.
Correct:Lulu loves baking, her husband, and her cats.
10. Use the vocative comma to clarify meaning.
- Incorrect:It hurts Maya.
Correct:It hurts, Maya.
11. Use semicolons instead of commas in complex lists, where elements already contain internal punctuation.
- Incorrect:We have offices in Melbourne, Australia, Hamburg, Germany, and Vancouver, Canada.
Correct:We have offices in Melbourne, Australia; Hamburg, Germany; and Vancouver, Canada.
12. Use commas both before and after a parenthetical element.
- Incorrect:Our flight to Bali, Indonesia has been rescheduled.
Correct:Our flight to Bali, Indonesia, has been rescheduled.
What is a comma?
A comma indicates a pause and also clarifies meaning. It can help you make a list, set off phrases, separate clauses, and indicate that a detail is nonessential in a sentence. Since it serves so many functions, the poor little comma is not just the most used but also the most misused punctuation mark.
The comma splice
A comma splice happens when you use a comma to join two independent clauses. (An independent clause is one that could stand by itself as a sentence.)
- Incorrect:I went to buy tomatoes, I bought potatoes instead.
Uh-oh! We have two independent clauses joined by a comma. And how do we know these clauses are independent? Each could stand alone by itself and make sense as a sentence.Correct:I went to buy tomatoes. I bought potatoes instead.Use a period to end a sentence and then start another one.Correct:I went to buy tomatoes; I bought potatoes instead.A semicolon indicates a closer relationship (e.g., contrast) than that signified by a period.Correct:I went to buy tomatoes, but I bought potatoes instead.Join the two independent clauses using a coordinating conjunction (e.g., but, and, or). You can then use a comma.Correct:Though I went to buy tomatoes, I bought potatoes instead.We’ve made the first a dependent clause by using a subordinating conjunction (e.g., though, since, until, because). Inserting a comma is fine now to separate the two clauses.Correct:I went to buy tomatoes but bought potatoes instead.Combine both into a single clause with just one subject. (Notice how the subject “I” appears just once in the sentence?) Now we just need a period at the end and no commas at all.
Here are some more sentences rescued from the comma splice.
- Incorrect:We made our bookings for Mauritius in January, should we now cancel them?
Correct:We made our bookings for Mauritius in January. Should we now cancel them?
Correct:We made our bookings for Mauritius in January; should we now cancel them? - Incorrect:The dodo was a flightless bird that went extinct, it was last seen in 1662.
Correct:The dodo was a flightless bird that went extinct. It was last seen in 1662. - Incorrect:Farley dabbed wildly at the stain, he only made it worse.
Correct:Farley dabbed wildly at the stain. He only made it worse.
Correct:Farley dabbed wildly at the stain; he only made it worse.
Correct:Farley dabbed wildly at the stain, but he only made it worse.
Correct:Farley dabbed wildly at the stain, which only made it worse.
Correct:Farley dabbed wildly at the stain but only made it worse.
In creative writing, authors sometimes use the comma splice to pull readers through to the end of a thought by marking a shorter pause than that indicated by a semicolon or a period.
- “Life is not like the dim ironic stories I like to read, it is like a daytime serial on television.”
—”Hugh and Margaut,” Something I’ve Been Meaning to Tell You, Alice Munro, 1974
In formal writing though, such as academic or business writing, avoid the comma splice.
After a verb
Don’t unnecessarily insert a comma between a verb and its object.
- Incorrect:Maya can’t believe she just saw, a UFO over the mountain.
Correct:Maya can’t believe she just saw a UFO over the mountain. - Incorrect:After much thought, Nesbit bought, a new laptop in November.
Correct:After much thought, Nesbit bought a new laptop in November. - Incorrect:Poco asked, whether we had any tickets left.
Correct:Poco asked whether we had any tickets left.
A comma may sometimes be appropriate after a verb—for instance, if the verb is followed by a parenthetical element.
- Nesbit bought, quite unnecessarily, a new laptop in November.
- Poco asked, however, if we had any tickets left.
Remember to close a parenthetical element: insert a comma not just before but also after the element.
- Incorrect:My friend, however is a ghost.
Correct:My friend, however, is a ghost. - Incorrect:Maya wanted, more than anything to travel the world.
Correct:Maya wanted, more than anything, to travel the world.
Before a verb
A comma isn’t needed between a subject and a verb.
- Incorrect:The cat, was white with black spots.
Correct:The cat was white with black spots. - Incorrect:The cat we adopted from the shelter, was white with black spots.
When the subject (the cat) and verb (was) are far away from each other—like here, where they’re separated by a descriptive clause—writers may mistakenly insert a comma before the verb.Correct:The cat we adopted from the shelter was white with black spots.
- Incorrect:The story Maya wrote last year during her trip to Thailand, was about a woman who’d lost her hat.
Correct:The story Maya wrote last year during her trip to Thailand was about a woman who’d lost her hat. - Incorrect:Rita’s entire family including her great-grandmother, are explorers.
Correct:Rita’s entire family including her great-grandmother are explorers.
Again, a comma may be appropriate if the verb is preceded by a parenthetical element.
- Poco’s car, which he bought just last month, has stopped running.
- All our plans, including our trip to Sri Lanka, have been canceled.
The additional detail enclosed within commas is nonessential information.
Of course, commas should then be used both before and after the parenthetical element.
After a conjunction
Don’t unnecessarily insert a comma after conjunctions like and, but, though.
- Incorrect:Anita tried contacting you but, you were unavailable.
Correct:Anita tried contacting you, but you were unavailable. - Incorrect:Lulu wore her red sweater though, it was a hot summer day.
Correct:Lulu wore her red sweater, though it was a hot summer day. - Incorrect:Farley will keep on betting until, he loses all his money.
Correct:Farley will keep on betting until he loses all his money.
Use a comma before coordinating conjunctions (but, and, or, yet, so) joining two clauses.
- You can count the rubies, and I’ll count the diamonds.
Use a comma before conjunctions of contrast (though, although, whereas, while, etc.) joining two clauses.
- I thought koala bears were bears, whereas they are actually marsupials.
Commas are usually not needed before other subordinating conjunctions (because, until, since, once, etc.).
- Rita climbed the mountain because it was there.
Comma before while and when
Don’t use a comma before while when it means “at the same time as.”
- Incorrect:Farley likes to sing, while doing the dishes.
Correct:Farley likes to sing while doing the dishes. - Incorrect:Make hay, while the sun shines.
Correct:Make hay while the sun shines.
Use a comma before while when it means “whereas.” (Contrast clauses usually take commas.)
- Correct:Poco has been promoted to CEO, while Farley has been fired.
Similarly, a comma is appropriate before when when the word is used to mean whereas.
- Correct:Many think that pangolins are reptiles, when they’re actually mammals covered in scales.
With reported speech
Don’t use a comma to introduce reported (or indirect) speech—words you are reporting and not directly quoting.
- Incorrect:Tumkin said that, he was in Mauritius.
Correct:Tumkin said that he was in Mauritius. - Incorrect:Farley thought, he had won.
Correct:Farley thought he had won. - Correct:Tumkin said, “I’m in Mauritius.”
Direct speech is introduced using a comma.
- Correct:Farley thought, “I have won!”
With essential elements
When a phrase or clause is essential to the meaning of a sentence, don’t set it off with commas.
- Incorrect:The architect, who designed this museum, was a genius.
The relative clause, “who designed this museum,” identifies the person we’re speaking about. It is therefore essential to the meaning of the sentence. Don’t use commas.Correct:Essential: The architect who designed this museum was a genius.
- Incorrect:Remiramen Femy who designed this museum was a genius.
We’ve already identified the architect as Remiramen Femy. The clause, “who designed this museum,” provides additional information and should be enclosed in commas.Correct:Nonessential: Remiramen Femy, who designed this museum, was a genius.
As you can see, commas affect meaning by indicating whether a detail is essential or nonessential.
- Correct:Essential: The inventor Nikola Tesla remains an enigma.
There have been many inventors; of them, we speak of the one called Nikola Tesla. This information is essential to identify the subject of the sentence.
- Correct:Nonessential: The machine’s inventor, Minerva Dash, has received an award.
The subject of the sentence is the machine’s inventor. It is clear which person is being referred to, even if you don’t know their name. The name itself is additional information, thus enclosed in commas.
The comma after an introductory phrase is usually optional, though recommended if the phrase is four words or longer.
- Every morning in winter, Lulu likes to dance in the sunshine.
- On a clear night, you can see the craters on the Moon.
Sometimes the comma is necessary to clarify meaning and avoid a dangling modifier.
- Confusing: Sadly Farley lost his socks.
Did Farley sadly lose his socks, or was it sad that Farley lost his socks?Clearer: Sadly, Farley lost his socks.The comma clarifies that sadly modifies the entire sentence: it was sad that Farley lost his socks.
Between adjectives
Often, two or more adjectives modify the same noun.
- deep blue sea
Both deep and blue describe sea.
- an antique Swiss watch
- a hard-working, intelligent student
- a dark and silent house
As a general rule, use commas to separate adjectives if you can put and between them.(The order of such adjectives is interchangeable, and they are called coordinate.)
- a diligent and earnest student
a diligent, earnest student
an earnest and diligent student
an earnest, diligent student
Can you place and between the following adjectives?
- a kind, loving, caring human being
- a cute, funny dog
- a decrepit, doddering old man
- a strange, mysterious message
If placing and between two adjectives sounds wrong, don’t use a comma either. Such adjectives are cumulative and build upon each other to modify the noun.
- Incorrect:the wrong and email address
And sounds wrong here. Don’t use a comma between the adjectives.Incorrect:the wrong, email address
Correct:the wrong email address - Incorrect:deep and blue sea
Incorrect:deep, blue sea
Correct:deep blue sea - Incorrect:antique and Swiss watch
Incorrect:antique, Swiss watch
Correct:antique Swiss watch - Incorrect:a cheap and plastic chair
Incorrect:a cheap, plastic chair
Correct:a cheap plastic chair
There are many reasons to use a comma in a sentence, but just as many not to.
In complex lists and series
If the items in a list already contain internal punctuation, use semicolons instead of commas to separate them.
- Incorrect:Maya visited Phuket, Thailand, Hanoi, Vietnam, and Surabaya, Indonesia.
The use of commas between items that already contain commas makes this list confusing.Correct:Maya visited Phuket, Thailand; Hanoi, Vietnam; and Surabaya, Indonesia.
- Incorrect:Our milestones are as follows: October 27, 2033, January 9, 2035, August 11, 2037, and December 21, 2039.
Correct:Our milestones are as follows: October 27, 2033; January 9, 2035; August 11, 2037; and December 21, 2039.
The missing comma
After interjections
Use a comma after an interjection.
- Incorrect:God eggs are delicious!
“God eggs”?Correct:God, eggs are delicious!
- Incorrect:Yes men are human.
Are “yes men” human?Correct:Yes, men are human.
- Incorrect:Oh Don would know!
Who’s “Oh Don”?Correct:Oh, Don would know!
The missing vocative comma
When you directly address someone, enclose the name or form of address in commas.
- Less clear: I’m cooking my love.
Use commas to make the sentence less scary.Clearer: I’m cooking, my love.
- Less clear: Tumkin has the airline called?
A comma would make this question easier to read.Clearer: Tumkin, has the airline called?
- Less clear: I know Poco and I think you’re right.
Use commas to clarify that the speaker is addressing someone called Poco.Clearer: I know, Poco, and I think you’re right.
In lists
Don’t forget to use commas between the items in a list.
- Incorrect:The elderly children and pregnant women are at greatest risk.
“Elderly children”?Correct:The elderly, children, and pregnant women are at greatest risk.
- Incorrect:Rita bought sauce eggs and yogurt.
“Sauce eggs”?Correct:Rita bought sauce, eggs, and yogurt.
The comma after the second-last element in a list (usually before and) is called the serial comma and is optional. Its use is more common in American than in British English, where it is generally used only when needed to clarify meaning.
- Confusing: My idols are my parents, Neil Armstrong and Mae Jemison.
Sounds like my parents are Neil Armstrong and Mae Jemison.Clearer: My idols are my parents, Neil Armstrong, and Mae Jemison.
After parenthetical elements
Commas used to set off information come in pairs: remember to “close your commas”—that is, use a comma both before and after the phrase or clause.
- Poor: Our trip to Phuket, Thailand just got canceled.
“Our trip to Phuket” reads as the introductory phrase, which implies that Thailand just got canceled!Better: Our trip to Phuket, Thailand, just got canceled.
- Poor: On May 19, 2020 we were supposed to reach Mauritius.
Better: On May 19, 2020, we were supposed to reach Mauritius.
After appositives
If you use a comma before an appositive, use one after as well. (An appositive is a noun phrase that appears right beside another noun phrase and describes it.)
- Incorrect: My friend, an editor recommends the use of serial commas.
Correct My friend, an editor, recommends the use of serial commas. - Incorrect: My sister, Minerva Dash is an architect.
Correct My sister, Minerva Dash, is an architect.
Usage guide
A comma indicates a meaningful pause between words in a sentence. Before you use this handy little punctuation mark, consider whether it is required and how it affects the meaning of a sentence. Use a comma to separate clauses and punctuate lists. Also use it to show that an element is nonessential and that it provides extra information to the reader. Finally, remember to insert a comma both before and after a parenthetical element.