An em dash (—) creates a strong pause within a sentence. It can replace commas, parentheses, or a colon, often adding emphasis or signaling an interruption.
Em dashes for extra information
Use a pair of em dashes to set off information that could otherwise appear in parentheses or between commas.
- The conference—originally scheduled for May—was postponed.
- Her answer—though technically correct—did not address the main issue.
- The three finalists—all first-time applicants—will interview tomorrow.
- Our newest feature—automatic cloud backup—is now available.
- The restaurant—one of the oldest in the city—will close for renovations.
Removing the material between the dashes should leave a complete sentence:
The conference was postponed.
Em dashes for emphasis or explanation
A single em dash can introduce a conclusion, explanation, or important final detail.
- She wanted only one thing—an honest apology.
- The team finally identified the problem—a damaged cable.
- There was one person who could solve the puzzle—her sister.
- He packed everything he needed—clothes, food, maps, and a flashlight.
- After months of debate, the committee reached a decision—no.
A colon could work in many of these sentences, but the em dash generally feels more dramatic or conversational.
Em dashes for sudden changes or interruptions
Em dashes can show that speech or thought stops abruptly.
- “If you would just let me explain—”
- “Don’t tell me you forgot the—”
- I was about to call her when—wait, is that her outside?
- “The answer is clearly—” He stopped and checked his notes.
- I thought the meeting started at ten—but apparently I was wrong.
In dialogue, use an em dash when someone is interrupted. Use an ellipsis (…) when the speaker trails off gradually.
Em dashes instead of parentheses
Parentheses make information feel secondary; em dashes give it more prominence.
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With parentheses: The deadline (which had already been extended) passed on Friday.
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With em dashes: The deadline—which had already been extended—passed on Friday.
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With parentheses: Two departments (sales and marketing) opposed the proposal.
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With em dashes: Two departments—sales and marketing—opposed the proposal.
Em dashes instead of commas
Em dashes can make a sentence easier to read when the inserted phrase already contains commas.
- The supplies—paper, pens, folders, and labels—arrived this morning.
- Her closest colleagues—Person A, the project manager; Person B, the designer; and Person C, the editor—attended the presentation.
Formatting
In most American English styles, em dashes appear without spaces:
The result—although unexpected—was encouraging.
Some publications use spaces around them:
The result — although unexpected — was encouraging.
Either treatment can be acceptable; consistency matters most. An em dash is longer than both a hyphen (-) and an en dash (–). It can be typed with Alt+0151 on some Windows keyboards or Option+Shift+Hyphen on macOS. Many writing programs also convert two hyphens (--) into an em dash automatically.