Dashes 101

En and em dashes take their name from their lengths, which are equal to that of a capital N and M, respectively.

hyphen	en dash	em dash
-	–	—

The em dash, or long dash, can replace other types of punctuation to provide a stronger but less formal break in a sentence. Interestingly, the en dash, or short dash, functions in more varied ways than the em dash.

Use em dashes to

• replace two commas or parentheses that set off a non-essential element when that element requires emphasis or when it contains its own commas
  • Jen's bike—a brand new, custom-built Rocky Mountain—was stolen over the weekend.
• replace a single comma or semicolon used to separate two independent clauses when the second clause requires emphasis
  • Bring your own lawn chairs and food to the festival—but leave the alcohol at home.
  • You bring the lawn chairs—I'll bring the food.
• replace a colon that introduces explanatory words or phrases when what follows the colon requires emphasis
  • Arlo wrote an entire cookbook on his favourite food—lima beans!
• convey an abrupt break, hesitation or afterthought
  • I am certain—well, fairly certain—that I locked the door—maybe we should go back and check.
• attribute a quotation
  • Trees love to toss and sway; they make such happy noises (Emily Carr).

Use en dashes to

• join inclusive numbers
  • Please read pages 12-14 and be ready to discuss them on Tuesday.
  • Robertson Davies (1913-95)
• connect geographical names
  • Straddling the Alberta-Saskatchewan border, Lloydminster is the only Canadian city that is located in two provinces.
• attach a prefix or suffix to an unhyphenated compound
  • Hester's funding application to set up a fine arts-oriented community outreach program is under review.
• give scores
  • The Flames beat the Canucks 3-2 in overtime

Note: As a general rule, do not leave spaces around either em or en dashes.