When to use the em dash
The em dash is used when you want a strong break in a sentence. Instead of commas, colons/semicolons and parentheses are often used. Their purpose is to set part of a sentence apart by introducing a new clause that expands upon something you just said. They can be used either in the middle of the sentence, with two em dashes enclosing the clause, or used at the end of a sentence with one single em dash introducing the additional information. They are also used to show an interruption in dialogue.
Em dash examples
I’m shocked that you thought I—your sister—would steal from you
They've announced the new team manager—it’s Mark from HR
Most attorneys—at least the ones that I know—earn a lot of money
There’s a cake in the oven—red velvet cake
I’m not surprised you’re hungry—we haven’t eaten since breakfast
“Can I get you a glass of—actually, I don’t know what I have, let me check.”
How to use the em dash
The em dash is longer than an en dash. As a matter of fact, their names derive from their width, with the en dash being the same width as the letter N when typed on a keyboard and the em dash the same size as an uppercase M.
If you’ve ever come across em dashes in newspapers or magazines, you might assume they should be written with a space before and after. The Associated Press (AP) writing style recommends using spaces with em dashes. However, most other writing guides agree that space is not required before or after an em dash.
To type an em dash on most computers, hold down Alt and type 0151 on the number pad, then release the Alt key. Press the Shift + Option keys on a Mac computer, then press the minus key.
Em dash vs. en dash
Unlike em dashes, the shorter en dash is used to show a range of numbers, be it a period of time, age range, dates, or any other values. To help you get a better understanding of its use, here are some examples:
The wedding venue has a capacity of 200–250 people
I scored the most goals in the 1975–76 season
Let’s go on vacation from January 9–14
There are 25–30 children in my daughter’s class
To conclude, en dashes are used between two numbers to show range. In contrast, their longer counterpart, the em dash, sets off additional information to emphasize or give examples of what was previously stated.