How to Use Hyphens, En Dashes, and Em Dashes

This is part two in our original grammar series.

It turns out the little horizontal lines you’ve been sticking between words when you weren’t sure what sort of punctuation should go there are actually different lengths for a reason.

Go figure.

Which of the following should fill the blank?

1. The confident student begins the well_proofed punctuation test with no fear.

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2. This cunningly_written masterpiece poses no threat to the smart student.

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3. The student returns devastating right_ and left_handed punctuational volleys.

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4. She thinks the score is 3_0 and is almost sure she’s winning_but is she?

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5. The 21st_century_punctuation_loving student turns to the answers with trepidation.

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Answers 1. a. 2. d 3. b 4. c 5. c

Hyphens (-)

To smoosh or not to smoosh? Since hyphens (the shortest of the little horizontal lines) are used primarily in compound terms, you probably mostly encounter them when you’re trying to figure out when two or more words are functioning as one word. You tried the dictionary, but it wasn’t there. What now?

    • Phrasal adjectives (also called compound modifiers) are words that work together to modify nouns. Some examples are “Dumbledore-scented candle” (real thing), “equitably distributed chocolates” (not real thing), and “high-paying jobs for English majors” (jury’s still out). To figure out whether or not to hyphenate, start by asking yourself these questions:
      • If I don’t hyphenate, can anybody interpret the phrase in a way I don’t intend? For example, a “snuggly purple porcupine” is a porcupine that is both snuggly and purple (yes hug); a “snuggly-purple porcupine” is a purple porcupine whose color looks soft (no hug). Both constructions are just fine grammatically, and which one you use just depends on what you mean.
      • Does my phrasal adjective come after a verb? If yes, then typically you don’t hyphenate. For example, you could write “My well-educated porcupine is well educated.” You would make no sense, but you could take comfort in your grammatical excellence.
      • Does my phrasal adjective end in “ly”? Great. That makes it easy. No hyphens for you. You may comment on “this writer’s disturbingly frequent references to porcupines” with grammatical impunity.
      • How many words are in my phrasal adjective? More than two? For the most part you can apply the rules above to get constructions like “seventeenth-century purple-porcupine artwork” and “chocolate-dumbledore-candle-eating English majors.” Once in a while, however, it changes the rules for clarity’s sake, as in “On the contrary, I find this writer’s not-so-disturbingly-frequent porcupine references charming.”
    • Omissions can also be taken care of with hyphens when you feel silly saying things like “right-handed and left-handed porcupines.” To get rid of any silliness, you may write “right- and left-handed porcupines,” using the dash to signal the omission.
    • Prefixes are horrible things for hyphens. I wish I could spare you, but I can’t. You pretty much just have to look them up, either in your trusty dictionary or, failing that, your style guide.

En dashes (–)

An en dash is a dash the length of two hyphens, and has almost nothing to do with hyphens (I share your relief). It is used as follows:

  • between scores and number and date ranges to mean “to” or “through,” as in “The body of a porcupine is 2–3 feet in length,” or “My teacher has asked me to read pages 1–1,000,000 tonight,” or “I won the en dash contest 46–3.”
  • with no spaces on either side of it.
  • only when not preceded by the word “from”; tragically you have to spell out “I was fascinated by porcupines from 12 to 22.”
  • only when you decide to write your numbers as numerals; if you spell them out, there are no dashes for you in “I was fascinated by porcupines from twelve to twenty-two.”
  • in the case of directions, where you want to talk about your “Seattle–Chicago flight” (the en dash again means “to”).

There is one more case where you can use the en dash, and it’s really weird. If you want to describe a split between the right-wing and the left-wing porcupine political factions, it would be confusing to run it all together with hyphens since two distinct hyphenated ideas are being joined: “right-wing-left-wing polarization.” Instead, you stick an en dash between your two hyphenated terms, like this: “right-wing–left-wing polarization.” Even if the second term isn’t hyphenated but still functions as a unit, you would use an en dash, as in post–porcupine takeover. The en dash lets your readers know to take the words “porcupine” and “takeover” together and understand you are referring to the period after the rodent revolution. Swap the en dash for a hyphen and you’re suddenly talking about the takeover that happened post-porcupine—that is, after all the porcupines died. It is madness and a level of nit-pickery that you may hope to seldom encounter.

Em dashes (—)

Finally, we’ve arrived at the one you actually can sprinkle throughout your writing when you’re not sure what kind of punctuation to use. Well, sort of. Em dashes are the equivalent of three hyphens in length and can replace commas, parentheses, and colons. Why would you make the swap? Mainly because you feel like it, or are being overrun by your other punctuation. You’re also free to use them to indicate a break in thought or an interruption. Enjoy your rare grammar freedom as in the following examples:

  • An interruption: The hospitalized writer reflected, “Hugging the porcupine seemed like a good idea at the time, but—” “No, it didn’t,” the porcupine-hugger’s friend interjected.
  • Replacing a colon: I’m going to change the subject now to something different—snakes.
  • Replacing parentheses: Snakes are not as nice as porcupines—though they are nicer than spiders—and I thought my readers might be getting tired of porcupines.
  • A break in thought: Your readers aren’t getting tired of porcupines—they’re getting tired of dashes.
  • Replacing a comma: You may be right—so I’ll cap it here.