Of all the punctuation marks in the English language, none has had a stranger year than the em dash. It’s been quietly holding sentences together since long before typewriters existed — and suddenly, in the age of AI writing tools, it’s been recast as some kind of digital fingerprint. Let’s clear that up, and also just teach you how to use the thing properly, because it’s genuinely one of the most useful punctuation marks you’re probably underusing.
What Is an Em Dash?
An em dash (—) is a long horizontal punctuation mark used to create a strong break in a sentence — more emphatic than a comma, more flexible than a colon, and less formal than parentheses. Its name comes from old typesetting: it’s traditionally the width of a capital “M,” which is also where its shorter cousin, the en dash (–), gets its name (the width of a capital “N”).
Em dashes can:
- Set off a phrase for emphasis
- Signal an abrupt interruption or shift in thought
- Introduce a summary or explanation
- Replace commas, parentheses, or colons in the right context
Used well, an em dash adds rhythm and clarity to a sentence. Used constantly, it can make writing feel breathless or unfocused — more on that below.
Em Dash vs. En Dash vs. Hyphen
These three marks get confused constantly, and honestly, most style guides only reinforce the confusion because publications differ on spacing conventions. Here’s the clean breakdown:
| Mark | Symbol | Length | Main Job | Example |
|---|---|---|---|---|
| Hyphen | – | Shortest | Joins words or word parts | well-known author |
| En dash | – | Medium | Shows a range or connection | pages 10–20 |
| Em dash | — | Longest | Creates a strong break or pause | She opened the door — and froze. |
Quick way to remember it: a hyphen joins, an en dash connects a range, and an em dash interrupts.
For a deeper dive from a trusted source, see Merriam-Webster’s guide to em dashes, en dashes, and hyphens.
How to Use an Em Dash
There are three main jobs an em dash does in a sentence. Once you know them, you’ll start spotting places where it’s genuinely the best tool for the job.
1. To Signal an Interruption or Sudden Shift
“I was going to finish the report tonight — actually, I already did.”
The em dash mimics the way we interrupt ourselves in speech. It reads more naturally here than a comma or a period would allow.
2. To Set Off Extra Information
“My sister — who has never once been on time in her life — showed up an hour early.”
Using em dashes here makes the interruption stand out more than commas would, and feels less clinical than parentheses.
3. To Introduce a Summary, List, or Explanation
“Books, laptop, water bottle — I had everything I needed for the flight.”
This use puts the em dash at the end of a list or clause, right before the explanation or payoff. It also works as a single punchy final thought: “She didn’t apologize — not once.”
How to Type an Em Dash
This is the part almost nobody teaches, which is why most people just type two hyphens (–) or reach for an en dash instead. Here’s how to get the real thing on any device:
| Platform | Shortcut |
|---|---|
| Windows | Alt + 0151 (numeric keypad), or type word--word and let AutoCorrect convert it |
| Mac | Option + Shift + Hyphen (-) |
| Google Docs | Type word--word followed by a space — Docs auto-converts it |
| Microsoft Word | Type word--word, then type the next word — Word auto-converts on space |
| HTML / CSS | — or the Unicode character — (U+2014) |
| iPhone / Android | Press and hold the hyphen key on the symbol keyboard until dash options appear |
If none of those work in the moment, two hyphens (–) is the universally understood placeholder — most modern software will auto-correct it for you anyway.
Is the Em Dash a Sign of AI Writing?
Short answer: no — but here’s why everyone suddenly thinks so.
Since large language models like ChatGPT became widely used, the em dash has picked up a reputation as an “AI tell,” right alongside things like the word “delve” and suspiciously balanced three-part sentences. The theory goes that AI writing tools use em dashes more often than the average human writer, so spotting one — or several — in a piece of text has become an informal signal that it might be AI-generated.
There’s a kernel of truth in there. AI language models are trained on enormous amounts of edited, professionally written text — books, journalism, essays — where em dashes are used correctly and often. So the models learned to reach for them in exactly the situations described above: interruptions, asides, and punchy summaries. Combine that with a tendency to slightly overuse a “good” technique once it’s learned it, and you get text that reads a little more dash-heavy than typical casual writing.
But treating em dashes as an AI detector falls apart under any real scrutiny. The em dash isn’t a 2023 invention — it’s been a standard part of English punctuation for centuries, used by everyone from Emily Dickinson, who famously made it her signature stylistic device, to modern journalists, novelists, and your high school English teacher’s red pen. Plenty of skilled human writers use em dashes heavily and always have. Treating dash usage as proof of AI authorship punishes good, deliberate writing — and it’s trivially easy to fake in either direction, since an AI can be told to avoid dashes, and a human can genuinely just like using them.
The real takeaway: the em dash isn’t going anywhere, and it isn’t guilty by association. If a sentence is clearer and punchier with an em dash, use it. Don’t let a punctuation panic talk you out of good writing.
Common Em Dash Mistakes
- Overusing it. If every third sentence has a dash, the emphasis stops meaning anything. Save it for moments that actually need the punch.
- Confusing it with a hyphen. A hyphen (-) joins words, like well-known. It should never stand in for a full em dash break.
- Mixing spacing styles inconsistently. Pick word—word or word — word and stick with it throughout a document.
- Using it as a lazy substitute for a semicolon everywhere. Em dashes are punchier and less formal than semicolons, but if every joined sentence uses a dash, the writing starts to feel choppy instead of confident.
Frequently Asked Questions
Is it wrong to use two hyphens instead of an em dash?
It’s a common workaround, not a hard error, but it isn’t a proper em dash. Most software — Word, Google Docs, even iOS — will auto-convert -- into an em dash automatically, so let autocorrect do the work.
What’s the difference between an em dash and a hyphen?
A hyphen (-) joins words or word parts, like well-known. An em dash (—) is significantly longer and creates a pause or break in a sentence. They are not interchangeable.
Can you start a sentence with an em dash?
It’s unusual but not incorrect. It typically shows up in more stylized or literary writing to create emphasis right from the first word.
How many em dashes is too many in one piece of writing?
There’s no hard rule, but if you’re using more than one or two per paragraph, it’s worth checking whether a period, comma, or semicolon would actually serve the sentence better.
Quick Reference
- Symbol: — (longer than a hyphen and an en dash)
- Main use: creates a strong pause, interruption, or emphasis
- Spacing: no spaces (American style) or spaced (British/European style) — just stay consistent
- Mac shortcut: Option + Shift + Hyphen
- Windows shortcut: Alt + 0151
- Not an AI tell: it’s a centuries-old punctuation mark, not a giveaway
Quick practice: Add an em dash to this sentence — “I checked every drawer twice my keys were nowhere to be found.” (Answer: “I checked every drawer twice — my keys were nowhere to be found.”)