Period inside or outside parentheses?

Periods stay outside of parentheses for parenthetical sentences that consist of an incomplete sentence or list. If parentheses enclose a whole sentence, place the period inside of the closing parenthesis.

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Do periods go inside or outside of parentheses?

Periods and parentheses are two of the most basic punctuation marks to master for the English language. We use periods to mark the end of a sentence and parentheses to insert additional content. But since we inevitably use periods and parentheses within the same sentence, it’s essential to learn how to use them correctly. 

Two primary rules for using parentheses and periods in the same sentence

#1. Place periods inside of the parentheses when parenthetical material consists of a complete sentence. In this case, parenthetical sentences do not occur within another whole sentence. 

Correct:

  • “Feed the cats twice a day and no later than midnight. (They run away if you’re inconsistent on time.)”

Incorrect: 

  • “Please have the dogs go inside the house at night. (Just don’t let them sleep on the bed). 

#2. Use periods outside of parentheses when parenthetical material consists of a dependent sentence clause or list. 

Correct:

  • “I expect students to turn in their assignments completed, edited, and on-on time (I make exceptions for emergencies).”

Incorrect:

  • “All assignments should include bibliographies with MLA formatting (not APA.).” 

What are periods?

Grammarians refer to periods as “terminal” or “strong punctuation marks” because they mark the end of a sentence or a “full stop.” Unless you end a sentence with a question mark or exclamation point, all sentences must end with a period. 

For example, 

  • “This is an example sentence.” (For independent clauses and quotes, always enclose terminal punctuation with a closing quotation mark or parenthesis.) 

The only exception for terminal punctuations occurs when a sentence ends with a formal abbreviation or special character. 

Correct examples: 

  • “For returns, please ship your headphones to Beats Electronics, LLC.” 
  • “We have a flight to catch at 4:30 a.m.” 
  • “Tonight, we are watching Who’s Afraid of the Dark?”
  • “Stay tuned for a new episode of Don’t Look!” 

What about the ellipsis?

The ellipsis consists of three periods (also known as dot-dot-dot). Often found within newspapers to save printing space, an ellipsis formally conveys how part of the sentence or quote is missing from the original statement. 

If an ellipsis occurs at the beginning of a quote, that means the whole sentence started before the quoted phrase began. Likewise, a terminal ellipsis implies that the whole statement continues for a while longer. For example, 

  • “The two had been approached by television and movie executives in the past year…” 
  • “…Ms. Johnson wanted Mr. Stanton to tell her story.” 

–– The New York Times

What are parentheses?

Parentheses are round brackets that we use to provide in-text citations, lists, or side-notes to a sentence (like this, for example). As you might have noticed, parentheses consist of two brackets: 

  • Opening parenthesis: (
  • Closing parenthesis: )

The standard rule for parentheses is that they all must open and close. Writing a sentence without an opening and a closing parenthesis is like writing a sentence without a period

Can we use commas with parentheses?

Parentheses are tricky because they have specific grammar rules for other punctuation marks. For example, we never use a comma before an opening parenthesis, but we can use a comma after the closing parenthesis when necessary. For example, 

Correct: “I’m a complete sentence (a fun one at that), but I’m also an example.” 

Incorrect: “I’m a complete sentence, (a fun one at that), but I’m also an example.” 

Like many sentences with parenthetical clauses, we can use parentheses similarly to commas or em-dashes. In fact, we could have written, “I’m a complete sentence, a fun one at that, but…” or “I’m a complete sentence–– a fun one at that–– but…” 

However, using parentheses or em-dashes too often is distracting for readers. If adding accessory content is important for tone, try reconstructing the sentence into two statements or incorporating footnotes or endnotes. 

If we include a parenthetical list inside of a sentence, we always use commas to separate list-objects. For example,

  • “We visited several state schools (such as Oregon, Washington, Idaho, and Arizona), but we decided to go with online education.”
  • “Your natal birth chart uses your birth city, time, and date to analyze the composition of astral bodies (e.g., Venus, Mars, Saturn, etc.).” 

Now, you might notice how we use periods inside the parentheses while abbreviating “e.g.,” and “etc.” As long as the abbreviations are necessary and correct, there’s no problem using periods within any parenthetical list or statement. In our case, “e.g.,” means “exempli gratia” (‘for example’) and “etc.” means “et cetera” (‘and other things’). 

Other types of punctuation marks within parentheses

Outside of periods and commas, we can use question marks or exclamation points (or “exclamation marks” for British English) wherever necessary inside parentheses. For example, 

  • “My parents took us to Italy (which I loved!), where we visited family.” 
  • “Marilyn Monroe never won an Oscar (I don’t think?), but she is one of the most recognizable actresses in the world.” 

In either case, the question mark and exclamation point are exclusive to the parenthetical clause, and the rest of the sentence should end with a period

When to use parentheses?

The three most common ways to use parentheses is to insert accessory information into your writing, provide an abbreviation for a long, formal title, or to provide a citation for quoted material. 

Use parentheses to add accessory information

We call parenthetical sentences “accessory” because we should be able to remove the bracketed clause without obscuring the sentence’s meaning. For example, 

With parenthetical material: 

  • “I now have 50 plants (and yes, they are my “babies”), as opposed to the 72 that stood before the windstorm.” 

Without parenthetical material: 

  • “I now have 50 plants as opposed to the 72 that stood before the windstorm.” 

As shown above, we can remove parenthetical information without eliminating the meaning of a sentence. However, we can also use parentheses to clarify terminology or provide formal, scientific names. For example, 

  • “The horticulturist is selling the philodendron (‘Pink Princess’) for $350.” 
  • “People say the ‘Pink Princess’ (Philodendron erubescens) are rare, but they’re not.”

There are also times when parenthetical sentences occur outside of a complete sentence. For example, 

  • “I began homeschooling the kids on September 12. (Teaching is harder than it looks.)” 

For this particular example, it’s correct to treat parenthetical material as an independent clause and use a period inside the brackets. However, using parentheses in this manner is somewhat uncommon for formal writing. To write more fluidly, we recommend structuring the sentence as such: 

  • “I began homeschooling the kids on September 12 (which is harder than it looks).” 
  • Note: Since the second example now consists of a dependent clause (an incomplete sentence), the period goes after the closing parenthesis to mark the end of the entire sentence. 

Use parentheses for in-text citations

The second most common use of parentheses involves in-text citations, a formal writing practice that adheres to academic style guides like the American Psychological Association (APA) Publication Manual or the Modern Language Association (MLA) Handbook. 

APA and MLA style guides require in-text citations for formal writing to avoid plagiarism, direct audiences to sources within a bibliography, and add credibility to your writing. Regardless of the type of information you cite, all in-text citations occur at the end of a sentence while placing a period after the closing parenthesis. For example, 

APA: “A complete sentence with sourced information (Surname, p. 201). 

MLA: “A complete sentence with sourced information (Surname 201). 

While citing direct quotes, APA and MLA formats allow writers to parenthesize page numbers for the second mention and onward (just make sure your citations appear regularly for the same source). For example,

APA: “A complete sentence with the second mention of a source (p. 201). 

MLA: “A complete sentence with the second mention of a source (201). 

APA citations

Most APA citations parenthesize the author’s last name and year of publication (separated with a comma). But if you include a direct quote, be sure to add the abbreviation “p.” for “page” with the page number. If you reference a range of pages, use “pp.” and separate page numbers with an en-dash.

Basic in-text citations for APA: 

  • The first mention of source: (Surname, 2020). 
  • Direct quote from one page: (Surname, 2020, p. 201). 
  • Direct quote from page range: (Surname, 2020, pp. 201–202). 
  • Subsequent mentions of source: (p. 201) or (pp.201–202). 

MLA citations

MLA format omits commas and page abbreviations for in-text citations while parenthesizing the author’s last name and page number(s). Additionally, if you cite more than one source at a time, separate each citation with a semicolon (see below). 

Basic in-text citations for MLA: 

  • First mention or direct quote from the source: (Surname 201). 
  • Subsequent mentions or direct quotes from the same source: (201).  
  • Citing multiple sources: (Surname 201; Surname 401). 

How we cite information also depends on the source media (e.g., television shows, essays, books, dictionaries, websites, etc.). MLA requires nuanced source citations, so make sure to check out Purdue OWL’s citation guide if you don’t have an updated MLA Handbook

Use parentheses for acronyms and abbreviations

Lastly, we can use parentheses to disclose official acronyms or abbreviations for titles or proper names. To avoid writing the same title throughout your work, introduce the full title with an official abbreviation in parentheses, and then use the acronym for there on out. For example, 

First mention: “Senators disclose 2022 budget for the National Aeronautics and Space Administration (NASA).” 

Subsequent mentions: “NASA prepares to negotiate the budget to meet their financial needs for 2022.”

For standard abbreviations, such as “pacific time zone,” enclose “PT” with parentheses when necessary. For example, 

  • “The award show begins at 8:30 p.m. (PT).”

Special cases for parentheses

Parentheses are also necessary for writing chronological lists or phone numbers. For instance, most people parenthesize their area code and use hyphens to separate local digits of their phone number. For example, “(971)-971-9701.” 

Chronological lists also use parentheses to enclose numbers, roman numerals, or letters, and they always begin with a colon, use commas, and end with a period. For example, 

  • “To bake cookies: (a) preheat oven to 350 degrees, (b) grease cookie tray with shortening or butter, (c) position cookies on tray three inches apart, (4) bake cookies for approximately 12 minutes or until brown.” 

Test Yourself!

Feeling ready to master periods and parentheses for your writing? Challenge yourself with the following multiple-choice questions. 

  1. True or false: Periods go outside of parenthetical sentences when they consist of a whole sentence. 
    a. True
    b. False
  2. Which of the following are not forms of terminal punctuation? 
    a. Question mark
    b. Period
    c. Exclamation point
    d. Parentheses
  3. Periods do not terminate sentences that end with a _____________.
    a. Parenthesis
    b. Formal abbreviation
    c. Question mark
    d. Exclamation point
  4. Which of the following punctuation marks can work similarly to parentheses? 
    a. Commas
    b. Em-dashes
    c. Semicolons
    d. A and C
  5. Which of the following do we not use parentheses for?  
    a. Area codes
    b. Side notes
    c. Acronyms
    d. None of the above

Answers

  1. A
  2. D
  3. A
  4. D
  5. D

Sources

  1. Dashes & Parentheses.” Center for Academic Success, University of Illinois, Springfield, 2020. 
  2. Dashes, Parentheses, Brackets, Ellipses.” Writing Associates Program, Swarthmore College, 2020. 
  3. Garcia, S.E. “Tanqueray, Humans of New York Star, Brings in Over $1.5 Million in Donations.” The New York Times, 28 Sept. 2020.
  4. “How to use parentheses and brackets ( ) [ ].” Lexico, 2020. 
  5. In-text citations: the basics.” Purdue Online Writing Lab, Purdue University, 2020. 
  6. MLA in-text citation: the basics.” Purdue Online Writing Lab, Purdue University, 2020.