em dash

The em dash (—) is a long horizontal bar the width of a capital M, written with no spaces around it. It’s also known as the long dash and is a substitute for the colon, the semicolon, the comma or parentheses. However, it indicates a more emphatic or abrupt break in the sentence and is often considered to be less formal in style.

On this page

• Em dashes: Interruptions, pauses and clarifications
• Em dashes: Afterthoughts, corrections and repetition
• Em dashes: Emphasis
• Em dashes: Enumerations
• Em dashes: Material in apposition
• Em dashes: Parenthetic information
• Em dashes: Summarizing words and restatements
• Em dashes: Attributions
• Em dashes: Headings
• Em dashes: Lists and tables
• Em dashes: Other marks of punctuation

Em dashes: Interruptions, pauses and clarifications

You can use the em dash to indicate a pause or an interruption at the end of an unfinished statement:

In the example above, the dashes are used to indicate (1) a pause and clarification; and (2) an interruption.

Em dashes: Afterthoughts, corrections and repetition

You can use the em dash to introduce an afterthought, correction or repetition:

• Who will oppose—who are now opposed to the union?

Em dashes: Emphasis

You can also use the em dash to set off an emphatic word or phrase:

• Imagination—that’s what children’s authors need in order to be successful.
• Tomorrow, Mom is making quiche—from scratch.

Em dashes: Enumerations

You can use em dashes to enclose a list of terms that does not end the sentence:

• A number of processes—gassing, electroplating, soldering, casting, etc.—are used in the copper industry.

Em dashes: Material in apposition

Explanatory or defining material in apposition can be set off by em dashes to create greater emphasis than a colon or commas, or to make a sentence clearer when the apposition contains a comma:

• Increased government funding—an approach once hailed as a panacea for all society’s ills—is no longer an option today.
• You must use all three primary colours—red, blue and yellow—in your painting.

Em dashes: Parenthetic information

Although parenthetic information can be enclosed in commas, parentheses or em dashes, em dashes provide greater emphasis than commas or parentheses do. If parenthetic material contains internal punctuation or forms a complete sentence, use parentheses or em dashes, depending on the degree of emphasis you want to achieve or the closeness of the relationship to the rest of the sentence. Parentheses are generally used to enclose information that is more remote from the main idea of the sentence, whereas em dashes are used for material that is more closely related:

• Canada’s multicultural tapestry—woven from fibres of many vibrant colours—contributes to the country’s rich diversity.

Em dashes: Summarizing words and restatements

You can sometimes insert an em dash before the final portion of a sentence to clarify its relationship to the rest of the sentence. The em dash is often followed by a summarizing pronoun such as all or these or by key words that restate previous information:

• Rich stores of minerals, good agricultural land, forests stretching over millions of acres, and energetic and enterprising people—all these assure Canada a bright future.
• She’s throwing a party on St. Patrick’s Day—March 17.

Em dashes: Attributions

You can use the em dash to indicate the author or source of a quotation:

Note that the attribution can appear in a number of places:

• on the line below the quotation, aligned with the left edge of the quotation
• on the line below the quotation, aligned with the right-most edge of the quotation
• directly after the quotation, with a space before the em dash

Em dashes: Headings

You can also use an em dash to separate the heading of a chapter or section from the description of its contents or to separate subheadings within a chapter or section, as in a catalogue:

• Gelatin Membrane Filters, White, Plain, Sartorius—A water soluble filter developed solely for…
• Appendix A—Table of Symbols
• ISO 2382-1994 Information-processing systems—Vocabulary—Part 14: Reliability, maintenance and availability

Em dashes: Lists and tables

In informal text, em dashes are sometimes used in place of bullets, numerals or letters in vertical lists:

In tables, the em dash can mean “nil” or “unknown”:

Example of em dashes used to represent unknowns

Element	Atomic weight	Density	Melting point
Actinium	227	—	—
Aluminum	26.98	2.7	660

Em dashes: Other marks of punctuation

Em dashes are generally not combined with other marks of punctuation. For example, don’t use a period before an opening or closing em dash, unless it follows an abbreviation; and be sure not to use the colon-dash (:—) to introduce a quotation or a list.

• When he got home after work—around 11:30 p.m.—he went straight to bed. [no comma after work]

However, do use a question mark at the end of a question enclosed within em dashes. Similarly, use an exclamation mark at the end of an exclamatory statement framed by em dashes.

• The director needs to speak to Henrik—is he here yet?—about the quarterly report.
• I was deep in thought, and then—eureka!—the solution came to me.