When to Use a Period
Use a period as follows:
- To end a sentence
- To mark the end of an incomplete sentence (or sentence fragment)
- In abbreviations with lowercase letters (e.g., i.e.)
- To separate initials before a surname (L.M. Montgomery)
- At the end of a sentence that sounds like a question but is actually a request or an order
- At the end of individual points in a list if they are complete sentences
A period isn’t needed at the end of a sentence that already ends in a question mark or an exclamation point.
What is a period?
A period or full stop (.) is a punctuation mark that marks the end of a thought. It indicates a longer pause than a comma or a semicolon and tells readers they have reached the end of a sentence. Periods are also used in abbreviations, after initials in names, and to mark the end of a fragment or minor sentence.
- We need more time.
- We spoke with Dr. Dash.
- This book was written by L. M. Montgomery.
- Everything was louder. The tick of the clock. The whirring fan. The horns honking themselves hoarse through rush-hour traffic.
Spacing around periods
Don’t insert a space before a period; do insert one after.
- Lulu likes to be happy. Whenever life lets her, she smiles, she dances, she sings. If you ask why she is endlessly cheerful, she says, “If I have nothing to be sad about, I’m happy.” Of course this gets on everybody’s nerves. They love her, but her chirpiness can be slightly creepy, especially on Monday mornings.
In general, insert one space, not two, after a period. Two spaces were useful when typing on typewriters, where all the letters were the same size. But on computers today, we generally use proportional fonts—where, for example, the letter “i” occupies less space than “m”—and one space suffices to visually separate sentences for the reader.
Periods with other punctuation
If a sentence already ends in a question mark or an exclamation point, omit the period.
- Incorrect In college I read Do Androids Dream of Electric Sheep?.
Correct In college I read Do Androids Dream of Electric Sheep?
- Incorrect Tumkin’s favorite Terry Pratchett novel is Guards! Guards!.
Correct Tumkin’s favorite Terry Pratchett novel is Guards! Guards!
Question marks and exclamation points are terminal punctuation, just like periods—that is, they appear at the end of sentences. To avoid redundancy, don’t use a period after you’ve already used these punctuation marks.
An abbreviation that ends in a period may appear at the end of a sentence. Don’t add another period after it.
- The living room was full of knickknacks: clocks, photos, shells, etc.
The abbreviation etc. ends in a period; no additional period is required to end the sentence.
- In the nineties, Farley worked as a test driver for Acme Inc.
With quotation marks
In American English, periods always go inside the quoted text—before the closing quotation mark.
- Tumkin said, “I leave for Denmark on Friday.”
- Poco will, of course, claim to be an “expert.”
- Maya’s favorite poem is Auden’s “As I Walked Out One Evening.”
In British English, whether a period (or full stop) goes within or outside quotation marks depends on where it belongs. If it belongs to the text enclosed by quotation marks, it goes inside. If not, it appears after the closing quotation mark.
- Tumkin said, ‘I leave for Denmark on Friday.’
The period belongs to the quoted text, so it goes inside. Note also that single quotation marks are generally preferred in British English, with double quotation marks being reserved for quotes within quotes.
- Poco will, of course, claim to be an ‘expert’.
The word inside quotation marks doesn’t own the period, so it goes after.
- Maya’s favorite poem is Auden’s ‘As I Walked Out One Evening’.
With parentheses or brackets
If the text inside parentheses (or brackets) is nested within another sentence, the period belongs to the entire sentence and appears after the closing parenthesis.
- At the space station, we have scientists of all species (Terran, Martian, and Durandian).
- This shelter is for all small animals (including birds and turtles).
- I’ll eat anything you serve (except eggs, bread, cereal, milk, cheese, juice, and sausages).
If the enclosed text is meant to stand alone as a sentence, it gets its own period, which goes inside the parentheses.
- At the space station, we have scientists of all species. (We are an equal-opportunity employer.)
- This shelter is for all small animals. (We provide a home to dogs, cats, rabbits, birds, and turtles.) Oh, I’m not fussy about breakfast. (I’ll eat anything you serve except eggs, bread, cereal, milk, cheese, juice, and sausages.)
Sometimes, the text enclosed in parentheses may be a complete sentence but still belong to another sentence. To indicate this relationship, place the period after rather than before the closing parenthesis. Don’t use two periods.
- At the space station, we have scientists of all species (we are an equal-opportunity employer).
- This shelter is for all small animals (we provide a home to dogs, cats, rabbits, birds, and turtles).
- Oh, I’m not fussy about breakfast (I’ll eat anything you serve except eggs, bread, cereal, milk, cheese, juice, and sausages).
If the final word in the enclosed text is an abbreviation that ends in a period, place periods both before and after the closing parenthesis.
- Incorrect This shelter is for all small animals (dogs, cats, rabbits, etc.)
CorrectThis shelter is for all small animals (dogs, cats, rabbits, etc.).
Periods are often used in abbreviations, especially ones with lowercase letters or those that are contracted forms of longer words.
Abbreviations don’t always contain periods (PhD, MBA, USA). Differences also exist between British and American English. For a complete discussion, see Periods in Abbreviations and Acronyms.
After initials in names
Periods are often used after initials that appear before a person’s surname.
- A. A. Milne
- T. S. Eliot
- A. S. Byatt
- M. Night Shyamalan
- Ernest J. Gaines
When initials are used by themselves to stand for an entire name (without a surname), no periods are used (John F. Kennedy but JFK).
Periods are generally not used to punctuate items or bullet points in a list, unless they are complete sentences.
- Lulu wished for three things:
Periods aren’t required, since each bullet point is a phrase rather than a sentence.
- World peace
- Blue flowers
- Three more wishes
If the individual items in a list are complete sentences, punctuate them using periods.
- To summon the genie, follow these steps:
- Rub the side of the magic lamp.
- Insert your credit card in the slot under the spout.
- Tap the lid three times to confirm payment.
To mark a fragment
Use a period not just at the end of a complete sentence but also to mark the end of a thought that may be only a fragment (or an incomplete sentence). Fragments, considered poor style in formal writing, appear often in fiction, creative nonfiction, and marketing materials.
- There are counsellors at the ready. Kindness and understanding. Life is harder for some, we’re told. Not their fault, even if the blows are purely imaginary. Felt just as keenly by the recipient, or the non recipient, as the case may be.
— Alice Munro, Dear Life (2012)
- Everything moved me. A dog following a stranger. That made me feel so much. A calendar that showed the wrong month. I could have cried over it. I did. Where the smoke from the chimney ended. How an overturned bottle rested at the edge of a table.
— Jonathan Safran Foer, Extremely Loud & Incredibly Close (2005)
- Your favorite detergent. Now free with our brand new washing machine. Buy today!
In an ellipsis
An ellipsis is a punctuation mark comprising three periods in a series. It indicates omitted material in quoted text.
And so . . . I still have a dream.— Martin Luther King, Jr., I Have a Dream (delivered August 28, 1963)
Period vs. question mark
Not all sentences end in a period. Questions, for example, end in question marks rather than periods. This affects intonation—how the sentence is read aloud. In casual communication, a sentence structured as a declarative may end in a question mark.
- You didn’t call him?
Question: Rising intonation
- You didn’t call him.
Statement: Falling intonation
Requests framed as questions
Sometimes, a request or an order is framed as a question. Despite its structure, you can end such a sentence with a period instead of a question mark if it isn’t meant to be read aloud as a question.
- Will you please sit down.
An instruction rather than a question (imperative, not interrogative). Compare this with the tone used to say, “Would you like to sit down?”
- Can everybody stop talking for a minute, so I can hear what the Durandians are saying.
The intonation is not meant to be interrogatory but imperative (not a question but a request or a command).
In reported questions
A question mark appears at the end of a question when you quote it directly.
- Direct speech: Maya asked, “Why are we singing?”
- Direct speech: Tumkin wondered, “What are we fighting for?”
When you report such questions, they become declarative sentences that should end in a period rather than a question mark.
- Incorrect Reported speech: Maya asked why they were singing?
Correct Reported speech: Maya asked why they were singing.
- Incorrect Reported speech: Tumkin wondered what they were fighting for?
Correct Reported speech: Tumkin wondered what they were fighting for.
Period vs. semicolon
You can separate two sentences with a period. But if you want to juxtapose two thoughts, perhaps to show a connection or contrast, you can use a semicolon instead of a period.
- Farley continued eating his pasta; he didn’t know his boots were on fire.
A semicolon signifies a closer connection between the clauses than that indicated by a period.
- Poco said he would send help; he lied.
A semicolon represents a shorter pause than a period but a longer one than a comma. By using it between two balanced sentences, you tell your reader that although your first thought has ended, the next one is closely connected to it; the sentence hasn’t yet ended.
Period vs. comma
A comma is used within a sentence, while a period is used to end it.
- We had oranges, but we didn’t have a blender.
In formal writing, don’t use a comma where a period should go—between two sentences. This error, called the comma splice, is frowned upon greatly in academic and business writing.
- Poor Poor: We had oranges, but we didn’t have a blender, we had to squeeze the pulp out by hand.
Better Better: We had oranges, but we didn’t have a blender. We had to squeeze the pulp out by hand.
In creative writing, however, a writer may use a comma instead of a period to indicate a shorter pause and pull the reader through to the end of a thought.
At last she was finished, we stepped off our machines, I passed her a towel, we walked together to the editing room.— Zadie Smith, Swing Time (2016)
When not to use a period
Don’t use a period after headings, subheadings, captions, headlines, or titles of books or movies and other works.
- War and Peace
- The Dark Side of the Moon
- Table 1:Long-Term Side Effects
Periods are also omitted in addresses.
- Editing Inc.
33 Markup Drive
Dashenham, New Manuscript
Don’t use a period when you sign off in a letter or an email.
- Yours sincerely,
Examples from literature
Here are some examples of first sentences from famous novels. Note how they all end in a period.
- Mrs. Dalloway said she would buy the flowers herself.
— Virginia Woolf, Mrs. Dalloway (1925)
- I write this sitting in the kitchen sink.
— Dodie Smith, I Capture the Castle (1948)
- I am an invisible man.
— Ralph Ellison, Invisible Man (1952)
- It was a pleasure to burn.
— Ray Bradbury, Fahrenheit 451 (1953)
- It was love at first sight.
— Joseph Heller, Catch-22 (1961)
- Time is not a line but a dimension, like the dimensions of space.
— Margaret Atwood, Cat’s Eye (1988)