A hyphen is the short mark that joins words or parts of words, as in self-employed or twenty-one. Dashes are longer, and they separate: the en dash marks a range, such as pages 10 to 20, and the em dash sets off a break or an aside in a sentence.
In writing, dashes and hyphens look very similar: just short horizontal lines, right? But they have different jobs, and mixing them up is a common mistake that many people make without knowing it.
Hyphens
A hyphen is a punctuation mark that joins words, or parts of words, to show that they belong together and share one meaning. You often see it in compound words such as self-employed, sphere-like, and post-war. That is what a hyphen is for: to connect.
Here are some more examples:
Mary went on a seven-day cruise.
It is clear that Mary did not go on seven different cruises that each took place during the day. She went on one cruise that lasted seven days.
Don't go inside that run-down building!
You know for sure that the building is not running anywhere, and it is not going down either: it is in bad repair.
A hyphen can also change the meaning of a word. For example:
Matt says I need to re-cover my fig trees, since the polar vortex is coming.
I have already covered my fig trees with thick layers of tarps, but Matt thinks that is not enough, so he tells me to cover them again.
Matt says I need to recover my fig trees, since the polar vortex is coming.
Matt thinks that no cover will help in a wind chill of minus 50 degrees, so he tells me to dig the trees up and bring them into the garage, where it is warmer.
Also use a hyphen when you write any of these:
- Compound numbers from 21 to 99: twenty-one, fifty-five, ninety-eight.
- Fractions written as words: one-fourth, two-thirds, three-eighths.
- Combined titles: writer-producer, singer-drummer.
For all the rules, read all you need to know about the hyphen.
Dashes
There are two kinds of dashes: the en dash, about as wide as the letter N, and the em dash, about as wide as the letter M. Both are longer than a hyphen.
The em dash
Use an em dash to make a strong break in a sentence, with more emphasis than a comma would give. For example:
- It's freezing in Minnesota—everything's frozen. The em dash joins the two parts, so that the second one lands like a punch line.
- The interior—especially the stones around the faux fireplace—sold it for me. A pair of em dashes in place of two commas gives the aside more weight.
- Link—not Zelda—is the name of the hero in green.
Most American style guides write the em dash with no space on either side; some, such as AP style, put a space before and after it. Choose one way and keep to it.
The en dash
Use an en dash for a range, in place of the word to: opening hours of 9 a.m.–5 p.m., books 1–7 of a series, children aged 7–12, or prices of $150–$379. In most styles, the en dash has no space before or after it.
Do not combine the en dash with from or between. Write either from 9 a.m. to 5 p.m. or 9 a.m.–5 p.m., never from 9 a.m.–5 p.m. In the same way, a price is between $150 and $379, never between $150–$379.
How to type a dash
Most keyboards have a key only for the hyphen:
- On Windows, hold down Alt and type 0150 on the number pad for an en dash, or 0151 for an em dash.
- On a Mac, press Option and the hyphen key for an en dash, or Option, Shift, and the hyphen key for an em dash.
- Many word processors also turn two hyphens typed between words into a dash automatically.
The guide to the en dash and the em dash covers both marks in more detail.
Conclusion
Now that you know the difference between dashes and hyphens, keep them apart. Knowing little things like these adds to your credibility as a writer.