En dash and em dash
En dash
To type an en dash, press ‘Alt’ + ‘0150’.
The en dash (–) is slightly wider than the hyphen (-) but narrower than the em dash (—). The typical computer keyboard lacks a dedicated key for the en dash, though most word processors provide a means for its insertion.
Span or range of numbers
The en dash is used to represent a span or range of numbers, dates, or time. There should be no space between the en dash and the adjacent material. Depending on the context, the en dash is read as “to” or “through.”
The 2010–2011 season was our best yet.
You will find this material in chapters 8–12.
The professor holds office hours every Wednesday, 11:00 a.m.–1:00 p.m.
If you introduce a span or range with words such as from or between, do not use the en dash.
Correct: She served as secretary of state from 1996 to 1999.
Incorrect: She served as secretary of state from 1996–1999.
Correct: The regime’s most oppressive treatment occurred between 1965 and 1970.
Incorrect: The regime’s most oppressive treatment occurred between 1965–1970.
Scores
The en dash is used to report scores or results of contests.
The president’s nominee was confirmed by the Senate, which voted 62–38 along party lines.
UCLA beat USC 28–14 in the final game of the regular season.
Conflict or connection
The en dash can also be used between words to represent conflict, connection, or direction.
The liberal–conservative debate.
The Los Angeles–London flight.
There is a north–south railway in the same area as the highway that runs east–west.
Compound adjectives
When a compound adjective is formed with an element that is itself an open compound or hyphenated compound, some writers replace the customary hyphen with an en dash. This is an aesthetic choice more than anything. For more on the hyphenation of compound adjectives, see here.
Hyphen: She is an award-winning novelist.
En dash: She is a National Book Award–winning novelist.
Hyphen: It was just one of many changes in this post-Clinton era.
En dash: It was just one of many changes in this post–New Deal era.
Hyphen: They were a bunch of college-educated snobs.
En dash: They were a bunch of prep school–educated snobs.
Hyphen: He submitted his manuscript to a print-only publisher.
En dash: He submitted his manuscript to an e-book–only publisher.
Em dash
To type an em dash, press ‘Alt’ + 0151.
The em dash is perhaps the most versatile punctuation mark. Depending on the context, the em dash can take the place of commas, parentheses, or colons—in each case to slightly different effect.
Notwithstanding its versatility, the em dash is best limited to two appearances per sentence. Otherwise, confusion rather than clarity is likely to result.
Do not mistake the em dash (—) for the slightly narrower en dash (–) or the even narrower hyphen (-). Those marks serve different purposes and are further explained in other sections.
Em dashes in place of commas
A pair of em dashes can be used in place of commas to enhance readability. Note, however, that dashes are always more emphatic than commas.
And yet, when the car was finally delivered—nearly three months after it was ordered—she decided she no longer wanted it, leaving the dealer with an oddly equipped car that would be difficult to sell.
Em dashes in place of parentheses
A pair of em dashes can replace a pair of parentheses. Dashes are considered less formal than parentheses; they are also more intrusive. If you want to draw attention to the parenthetical content, use dashes. If you want to include the parenthetical content more subtly, use parentheses.
Note that when dashes are used in place of parentheses, surrounding punctuation should be omitted. Compare the following examples.
Upon discovering the errors (all 124 of them), the publisher immediately recalled the books.
Upon discovering the errors—all 124 of them—the publisher immediately recalled the books.
When used in place of parentheses at the end of a sentence, only a single dash is used.
After three weeks on set, the cast was fed up with his direction (or, rather, lack of direction).
After three weeks on set, the cast was fed up with his direction—or, rather, lack of direction.
The em dash in place of a colon
The em dash can be used in place of a colon when you want to emphasize the conclusion of your sentence. The dash is less formal than the colon.
After months of deliberation, the jurors reached a unanimous verdict—guilty.
The white sand, the warm water, the sparkling sun—this is what brought them to Hawaii.
Multiple em dashes
Two em dashes can be used to indicate missing portions of a word, whether unknown or intentionally omitted.
Mr. J—— testified that the defendant yelled, “Die, a——,” before pulling the trigger.
From the faded and water-damaged note, we made out only this: “Was ne——y going to m—— K——, but now ——t.”
When an entire word is missing, either two or three em dashes can be used. Whichever length you choose, use it consistently throughout your document. Surrounding punctuation should be placed as usual.
The juvenile defendant, ———, was arraigned yesterday.
Spaces with the em dash
The em dash is typically used without spaces on either side, and that is the style used in this guide. Most newspapers, however, set the em dash off with a single space on each side.
Most newspapers — and all that follow AP style — insert a space before and after the em dash.
To set off the sources of quotes
Based on Wikipedia
A penny saved is a penny earned. — Benjamin Franklin