When we talk about dashes as punctuation, we are actually talking about three distinct things—the hyphen (-), the en dash (–) and the em dash (—). They serve different functions as punctuation marks, and it can be tricky to figure out how to use them in a sentence.
As a general rule, hyphens and en dashes bring things together; hyphens create compound numbers, nouns and adjectives, and en dashes show ranges of distance and time and are used to attach prefixes and some suffixes. Em dashes, though, break things apart. They are used to interrupt dialogue, interrupt the action of a sentence to add an aside or give emphasis to additional information. Taken together, the three dashes cover a lot of ground, so it is easy to lose track and over-use them, so here’s a quick primer on the three dashes and their uses.
Punctuation With Hyphens and Dashes
Use of hyphens, en dashes and em dashes is not standardized, but most style guides say to not have any spaces between hyphens and dashes and the surrounding letters. If you use a dash at the end of a sentence, such as with an em dash and interrupted dialogue, the dash takes the place of the final sentence punctuation.
The Hyphen(-)
Hyphens connect things that are closely related, such as words that combine to make a single idea or work together to describe something.
Compound Numbers
All numbers between 21 and 99 and fractions should contain a hyphen.
For example:
Twenty-one
Five-eights
He is seventy-five years old, but swears he feels like he’s only sixty-five.
Compound Adjectives
Consider these two sentences:
I saw a man-eating tiger!
I saw a man eating tiger!
These two sentences are about two very different things, and the difference is in the use of a hyphen to create a compound adjective.
Compound adjectives are formed when two or more adjectives are joined to modify the same noun. The hyphen eliminates confusion in the writer’s meaning, as seen in the examples above. The hyphen helps to firmly link the adjectives, allowing them to work together as a single unit to describe something. Without the hyphen, the sentence meaning becomes ambiguous or doesn’t make sense.
For example:
Janine made the all-too-common mistake of assuming that everyone loved anchovies as much as she did.
The recluse donated his fortune to the university to build a state-of-the-art observatory, but only if they named it after Marvin the Martian.
Given that he hated dogs, but loved snakes, George could easily be described as a cold-blooded kind of guy.
Note: Do not use hyphens to connect adjectives and adverbs (words that modify adjectives, usually ending in -ly). Since it is clear that the adverb is modifying the adjective, it is not necessary to include a hyphen.
For example:
Incorrect: Despite it being a terribly-cold day, Janice opted to wear her favorite sandals.
Correct: Despite it being a terribly cold day, Janice opted to wear her favorite sandals.
Incorrect: The highly-intelligent bird could quote Shakespeare, as well as recite pi to 80 digits.
Correct: The highly intelligent bird could quote Shakespeare, as well as recite pi to 80 digits.
Compound Nouns
Compound nouns are made up of two or more words—usually two nouns or a noun and modifying adjective. Compound nouns appear three ways: as one word (e.g, toothpaste, bathroom), separate words (e.g., Christmas tree, swimming pool) or words connected with a hyphen.
For example:
Mother-in-law
Dry-cleaning
Well-being
Hanger-on
Spelling Out Words in Text
Despite the fact that the dog clearly couldn’t read, Jane still made sure to spell out n-e-u-t-e-r when making his appointment with the vet.
Showing Stuttering, Stammering or Sobbing in Dialogue
“B-b-but my cake was the best!” Millicent sobbed, “I d-d-d-don’t understand why I didn’t win the b-baking contest!”
The En Dash (–)
Date, Time and Page Ranges
The en dash connects things related by a span of time or distance, such as date or page ranges.
For example:
I worked at Merry Mouse Pizza Palace from June 3–17, although it seemed much longer.
The reading selection for the writing assignment can be found on pages 14–477.
Other Connections and Ranges
Use and en dash to show connection or range between places or time.
For example:
To make matters more difficult, all six of her kids were kindergarten–elementary school age.
The trail eventually ran within sight distance of the U.S.–Canada border.
Prefixes and Suffixes
Use an en dash with the prefixes ex–, self– and all–; with the suffix –elect; and between prefixes and dates or capitalized words/proper nouns.
For example:
Ex–husband
Self–aware
All–inclusive
Mayor–elect
Mid–June
Pre–WWII
Mid–1990s
Post–Roosevelt America
Differentiating Between Similar Words
Sometimes adding a prefixes create words that can be misread as other words. Adding an en dash after the prefix can clarify your meaning.
For example:
Recollect (to remember) vs. Re–collect (to collect again)
Resign (to quit) vs. Re–sign (to sign again)
Prefixes and Double Vowels
Adding prefixes can sometimes create double vowels. Add an en dash to prevent these mistakes.
For example:
Semiindependent vs. Semi–independent
Reelect vs. Re–elect
Preeminient vs. Pre–eminent
The Em Dash
The em dash (—) is truly a jack-of-all-trades. It can be used like parentheses, commas, colons and semicolons in sentences, and can add additional thoughts or asides to a sentence, set apart appositives containing commas or indicate missing words. Good use of the em dash can add pop and flair to your writing, but overuse can make your writing look amateurish or diminish the power you were hoping for.
Em Dashes and Emphasizing Additional Information
Use em dashes to an interruption that is relevant to the sentence, but not part of it. This might be a list, example, summary, shift in tone or thought, or a dramatic point. Unlike parenthesis, which understate the information they contain, em dashes draw attention to the additional information in your sentence.
For example:
My academic adviser—who was one of the most unpleasant people I have ever met—tried to talk me into changing my major from microbiology to business.
When it was time to pack for my trip, I knew exactly which books I wanted to bring to the beach—Sense and Sensibility, Wuthering Heights and An Introduction to Quantum Mechanics.
I have never liked aviaries—I was attacked by a parakeet once and have never gotten over it.
Janine’s feelings—that we are part of a multidimensional universe and we are experiencing only a part of the entire realm of existence—remained unchanged.
In the above examples, the additional information could have been presented between parentheses, after a colon, with a semicolon or surrounded by commas. The use of em dashes brings brings the added information to the foreground of the sentence and elevates the importance of the information to equal the main ideas of the sentences.
Em Dashes and Appositives
Use em dashes with appositives that contain commas (an appositive is a noun or phrase that renames a noun or pronoun and is usually surrounded by commas).
For example:
The author’s new book—a sprawling, character-driven epic spanning centuries—was poorly received by critics, who were expecting a much more traditional take on an auto-repair manual.
Em Dashes and Dialogue Interruptions
You can also use the em dash to show a break or interruption of dialogue. Do not use a comma, period or similar final punctuation after the em dash.
For example:
As he attempted to hold the steering wheel and a cup of coffee in one hand and type into his phone with the other, Peter asked no one in particular, “Can someone watch the road while I—”
“The door is bolted shut. There’s no way the zombies are getting insi—” said Cassidy.
Em Dash Misuse
As with exclamation points, overusing em dashes can diminish their power. If everything is emphasized, then nothing stands out. A good writer will use em dashes sparingly—just in places that need the right amount of punch.
Using em dashes also de–formalizes your writing. If you are writing an informal email or fiction, em dashes can work very well. For formal and business writing, however, you will want to stick to more traditional punctuation like parentheses, commas, colons and semicolons, saving the em dash for those few instances when you really want to stand out.
Grammaphile 