Definition · Plain-language
Em dash
An em dash ( — ) is a long dash used to mark a strong break in a sentence, to set off a parenthetical remark, or to add emphasis — it is the most flexible of the dashes.
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What the em dash does
The em dash is the most versatile dash because it can stand in for several other marks. A pair of em dashes can enclose a parenthetical comment, much like brackets but with more emphasis: "Her proposal — bold and untested — won the vote." A single em dash can introduce an explanation or summary, as a colon does: "There was only one option left — retreat." It can also mark an abrupt change of thought or an interruption in dialogue. Because it draws the eye, the em dash adds emphasis and a slightly informal, energetic tone, which is why it should be used sparingly in very formal academic prose.
Em dash, en dash and hyphen
English uses three horizontal marks of different lengths for different jobs. The hyphen (-) is the shortest and joins words or parts of words: well-known, twenty-one. The en dash (–), about the width of a capital N, mainly marks ranges and connections: pages 10–20, the London–Edinburgh line. The em dash (—), the width of a capital M, marks breaks and parenthetical asides within a sentence. Confusing them is common, partly because keyboards do not have dedicated keys for the en and em dashes. Treat the three as distinct: hyphen for compounds, en dash for ranges, em dash for sentence-level breaks.
Spacing and style conventions
Style guides differ on whether to put spaces around the em dash. The Chicago Manual of Style and most American practice set it closed up, with no spaces: "the result—surprising—held". Much British and journalistic style uses a spaced en dash instead for the same job: "the result – surprising – held". Either convention is acceptable, but a document should use one consistently. Because the em dash is emphatic, overusing it makes writing feel breathless; if a sentence has several, consider whether commas, parentheses or a full stop would serve better. Used with restraint, the em dash is a powerful tool for pacing and emphasis.
Key facts
At a glance
- Definition: a long dash ( — ) marking a strong break or emphatic aside
- Width: about the width of a capital M
- Uses: parenthetical asides, abrupt breaks, emphasis, summary
- Can replace: commas, parentheses or a colon
- Not the same as: the en dash (–, ranges) or hyphen (-, compounds)
- Spacing: closed up (US/Chicago) or a spaced en dash (much UK style)
Common misconceptions
What people often get wrong
Often heard: The em dash, en dash and hyphen are interchangeable.
Actually: They do different jobs. The hyphen joins compounds (well-known), the en dash marks ranges (10–20) and the em dash marks sentence breaks and asides. Length and function distinguish them.
Often heard: Em dashes are too informal to use in serious writing.
Actually: Em dashes are entirely standard, including in published academic and literary prose. The advice is to use them sparingly for emphasis, not to avoid them; overuse, not use, is the problem.
Often heard: You must always put spaces around an em dash.
Actually: Spacing is a style choice. Chicago and most US style set the em dash closed up with no spaces, while much British style uses a spaced en dash for the same role. Pick one and stay consistent.
Going deeper
