Use an em dash (—) to set off an interruption, an aside, or an emphatic ending in a sentence; use an en dash (–) for ranges like 2019–2023 or pages 45–52; and use a hyphen (-) to join words such as well-known or part-time. They look similar but do different jobs, and mixing them up is one of the most common punctuation slips in formal writing.
The three marks at a glance
| Mark | Name | Main uses | Example |
|---|---|---|---|
| - | Hyphen | Joins words or parts of words | a part-time job |
| – | En dash | Ranges; connections between equal terms | pages 12–18; the Boston–Chicago route |
| — | Em dash | Breaks, asides, emphasis | The answer—if there is one—is simple. |
The names come from typesetting: the en dash was traditionally about the width of a capital N, and the em dash about the width of an M.
The em dash: the flexible one
The em dash is the most expressive mark of the three. It can do the job of commas, parentheses, a colon or a semicolon, with more emphasis.
1. To set off an aside (in pairs)
The new library—built on the site of the old bus station—opens in May.
Commas would work here too, but the dashes make the aside stand out more. Parentheses would make it quieter. Choose based on how much attention the aside deserves.
2. To add emphasis at the end of a sentence
She had one goal for the semester—sleep.
A colon would also be correct, but the dash feels more conversational and dramatic.
3. To mark an interruption or a sudden change
"I was going to tell you, but—"
We could take the train, or—actually, let's just drive.
4. To introduce a list or explanation inside a sentence
Three things decide the grade—the thesis, the evidence and the analysis—so start with those.
When the list contains commas, dashes keep the sentence readable where more commas would create confusion.
Spacing
Most American style guides, including Chicago and APA, write the em dash closed, with no spaces: word—word. AP style, used by many newspapers, puts a space on each side. Many British publishers use a spaced en dash in this role instead. None of these is wrong; just be consistent within a document.
Em dash, comma, colon or parentheses?
Since the em dash can stand in for several other marks, it helps to know what each one signals.
| Mark | Effect on the reader | Example |
|---|---|---|
| Commas | Smooth, neutral; the aside blends in | The library, built last year, opens in May. |
| Parentheses | Quiet; the aside is a side note | The library (built last year) opens in May. |
| Em dashes | Loud; the aside gets attention | The library—built in only eight months—opens in May. |
| Colon | Formal; promises an explanation or list | She had one goal: sleep. |
A good test: read the sentence aloud. If you'd pause and drop your voice, use parentheses. If you'd pause and raise your voice, use dashes. If there's barely a pause, commas are enough.
Also watch the structure. A pair of dashes works like a pair of brackets, so the sentence must still make sense when you remove everything between them. "The library—built in only eight months—opens in May" becomes "The library opens in May," which is fine. If removing the dashed part breaks the sentence, rewrite it.
Finally, avoid more than one pair of dashes in a sentence. "The plan—which nobody liked—was approved—eventually" leaves the reader unsure which dash closes which aside.
The en dash: ranges and connections
The en dash is the one most people don't know they need.
1. Ranges of numbers, dates and times
The exhibit runs May 3–June 14.
Read pages 45–52 before Thursday.
Office hours are 2–4 p.m.
Read it as "to" or "through." But don't mix styles: write "from 2019 to 2023" or "2019–2023," not "from 2019–2023." If you use "from" or "between," use words for the second part as well.
2. Connections between equal terms
the Paris–Berlin train
a Republican–Democrat agreement
the doctor–patient relationship
The en dash signals a relationship between two separate things, where a hyphen would suggest they are one combined thing.
3. Compound adjectives with an open compound
a post–World War II economy
a New York–based company
Here the en dash shows that "post" applies to all of "World War II," not just "World." This use is a finer point; some style guides prefer a hyphen, and many readers won't notice. Follow your guide if it specifies.
The hyphen: joining words
The hyphen is the shortest mark and the one on your keyboard.
1. Compound adjectives before a noun
a well-known author, a long-term plan, a five-page essay
After the noun, the hyphen is usually dropped: "The author is well known." Also, don't hyphenate after an adverb ending in -ly: "a highly rated course," not "a highly-rated course."
2. Some compound words and prefixes
mother-in-law, self-aware, ex-partner, re-enter
Dictionaries disagree on many of these, and usage changes over time ("e-mail" has mostly become "email"). When in doubt, check a current dictionary.
3. Numbers and fractions written as words
twenty-one, two-thirds of the class
4. To avoid confusion
re-cover a chair (versus recover from an illness)
a small-business owner (versus a small business owner, who might be short)
How to type each one
| Mark | Mac | Windows | Word or Google Docs |
|---|---|---|---|
| Hyphen | Hyphen key | Hyphen key | Hyphen key |
| En dash | Option + Hyphen | Alt + 0150 (numeric keypad) | Insert, then Special characters |
| Em dash | Option + Shift + Hyphen | Alt + 0151 (numeric keypad) | Often autocorrects from two hyphens |
On phones, press and hold the hyphen key to see dash options.
Before and after: fixing dash errors
Wrong: The meeting is 9-11 a.m. → Right: The meeting is 9–11 a.m.
Wrong: She finally found it - the missing file. → Right: She finally found it—the missing file.
Wrong: a highly-respected professor → Right: a highly respected professor
Wrong: from 2010–2015 → Right: from 2010 to 2015 (or simply 2010–2015)
Wrong: an up to date list → Right: an up-to-date list
Dashes in academic writing
Formal academic writing uses em dashes less than journalism or fiction, but they're perfectly acceptable. APA style, for instance, uses em dashes for interruptions and en dashes for ranges and for linking equal terms. For page ranges in citations, APA uses an en dash (pp. 45–52), while MLA examples often use a plain hyphen. When in doubt, check the guide your instructor assigns.
If you want to check your punctuation quickly, a grammar checker will flag many hyphen and dash mix-ups, such as a hyphen in a number range. ZeroTell's Grammar Checker highlights these alongside other errors.
Grammar CheckerFix grammar and phrasingReview its suggestions with this guide in mind, since some dash choices are about style, not correctness. If a sentence has become a tangle of dashes and commas, it's often easier to rewrite it as two sentences than to fix the punctuation.
Key takeaways
- Hyphen (-): joins words, as in well-known or twenty-one.
- En dash (–): ranges and connections, as in 2019–2023 or the Paris–Berlin train.
- Em dash (—): asides, emphasis and interruptions; use it sparingly.
- Choose a spacing convention for em dashes and keep it consistent.
- Don't pair "from" or "between" with an en dash range.