Give It To Me Straight: When to use the em dash, the en dash and the hyphen

April 30, 2021


You don’t have to be following the news too closely to know that here in Ontario, where I live, the pandemic’s third wave—or more properly, the new wave of “variants of concern”—is wreaking massive havoc.

While my family, friends and I are safe and healthy, so many others are not. Every day we read the gloomy reports: more cases, more deaths, more hospitals at breaking point, more and more medical and other essential workers straining under the physical and mental stress of it all. From all accounts, I’m not the only one who feels angry and upset that our governments have largely failed us.  

But I try not to get too bogged down in the mire, so when I see an opportunity to shift my outrage to something really serious—like improper punctuation—I jump on it. At least it provides a much-needed distraction.

The latest gaffe to catch my eye was this caption that appeared alongside a recent newspaper photo of people at Pearson International Airport: “Travellers lineup to be tested for Covid-19 on arrival in Toronto.”

Travellers lineup? Well now, “travellers lineup” is a noun. (Let’s agree to ignore the question of whether this is possessive and in need of an apostrophe.) This is a particular type of lineup, different from, say, a “police lineup” or, for all my running friends, a “start lineup.” (Remember those?)

But the photo depicted the travellers doing something – lining up. Clearly, the caption writer meant to use a verb: “Travellers line up to be tested for Covid-19 on arrival in Toronto.”  Two words, please, caption writer.

If you’re wondering if our captioner might have cured this egregious error by inserting a hyphen, so that “lineup” becomes “line-up,” the answer is no. According to precisely none of the dictionaries I consulted is “line-up” a legitimate word. Which isn’t to say that the English language doesn’t contain lots and lots of hyphenated words, but as we shall see, convention changes over time.

So, when do you use hyphens?

Let’s start with the uncontentious. Use a hyphen when:

  • spelling out fractions, like one-third, or numbers, like thirty-three or ninety-nine
  • creating an adjectival compound that contains a number, such as in 35-hour work week
  • spelling out individual letters in a word, as in L-E-G-I-T-I-M-A-T-E
  • splitting a word at the end of line (provided you do it properly; you can’t just stick a hyphen in anywhere you fancy!)

Do not hesitate to use a hyphen to create clarity. Are you planning to recover your sofa (after having lent it to a friend)? Or re-cover your sofa (because it’s old and shabby)? Did you reform the band (because they needed a change)? Or re-form the band (get them back together for the reunion tour)?

Hyphens should also be used to avoid what Lynn Truss (author of Eats, Shoots and Leaves) calls “letter collision”—the “unpleasant linguistic condition” that arises when we attempt to create compound words such as “de-ice” or “shell-like.” Without the helpful hyphen, these words can look like typos (“deice” and “shelllike”).

Which brings us to compound words in general. And, sadly, straight back into the mire.

Grammar Girl Mignon Fogarty says the rules about when to hyphenate a compound word are “squidgy.” Lynn Truss pulls fewer punches and calls them a “big bloody mess.”

The problem arises because language evolves over time. As Fogarty explains, compound words go from “open compound (two separate words), to hyphenated compound, to closed compound (one word with the two parts shoved together)—and sometimes back again—and the changes can seem arbitrary.”

So, while “light bulb” may have started out life as two words (and still appears as two in many dictionaries), it has also morphed into the legitimate “lightbulb.” But you’ll never see “incandescentlightbulb.” It’s just too long and awkward. Unless, of course, you’re German. You have only to consider a German word like “fallschirmspringerschule” (parachute jumper school) to understand that our European friends have no problem mashing together, not just two, but several parts, to invent a super-sized word.

You may have noticed that I hyphenated “super-sized” in that last sentence. That’s an example of a compound adjective or compound modifier. On this point, grammarians generally agree: compound modifiers should be hyphenated. This is for clarity. Without the hyphen, we don’t know if this is a “sized word” (whatever that might be) that is super or, a merely a large word. Of course, I could have continued with my German theme and substituted the word “uber,” thereby saving myself from yet another linguistic decision.

Alas, the English language is full of exceptions. Compounds formed from an adverb ending in “ly” do not take a hyphen. Again, the rationale is clarity. When we write “inconsistently applied rules” and “beautifully written sentences”, the meaning is clear; therefore, we don’t need to put a hyphen between “inconsistently” and “applied” or “beautifully” and “written.”

Returning to compound nouns, like “lightbulb” and “website”, and whether they should be one word, two words, or two words joined with a hyphen, it probably comes down to two parts current convention and one part personal style.

You won’t want to appear old fashioned by writing “web-site,” but if you prefer “inter-departmental” rather than the more streamlined “interdepartmental”, I wouldn’t argue it was wrong. For consistency’s sake, however, you or your company would do well to create a language style guide. At the very least, it may save you from going completely bonkers.   

Now what about the em dash and its shorter sibling, the en dash?

The em dash, so-called because historically, it was the width of a typeset capital letter M, serves a similar function to parenthesis (or brackets). To place a word, phrase or whole sentence in parenthesis is to say that the word/phrase/sentence is a secondary statement; it is “parenthetical” to your main thought.

While parenthesis tend to minimize the importance of the secondary thought, the dash does the opposite; it emphasizes the thought. As Mignon Fogarty explains, “a dash interrupts the flow of the sentence and tells the reader to get ready for an important or dramatic statement.” If knowing the origins of a word helps you remember how to use it, know this: "dash" derives from the Middle English “dasshen” which means “to knock, to hurl, to break.”

Compare these two sentences:

1.  His letter was published (in The New Yorker).
2.  His letter was published—in The New Yorker.

In sentence #1, the publication is secondary to, or parenthetical to, the main point, which is that the letter was published. The name of the publication adds useful information, but by putting it in brackets, the writer is relegating that information to the “nice to know”, but not essential, category.

In sentence #2, the fact that the letter was published is obviously good, but what is even more impressive is that it appeared in The New Yorker, not some local rag. In this case, the em dash makes more of a statement than either a comma or a colon, both of which would be correct.

Some style guide authors claim that the dash is less formal than parenthesis, and therefore, the dash should be saved for more casual writing. I say rubbish. These same authors point out the difference between parenthesis and dashes, so where’s the logic in that?

If you’ve been reading closely, you’ll have noticed that I love the em dash. I sprinkle it liberally throughout my copy, and you have my permission to do the same. And whether or not you put a space before and after the em dash is entirely up to you. Just decide and stick with it.

And so, we come to the en dash. Historically, the en dash was as long as a typeset capital letter N—in other words, longer than a hyphen but not as long as the em dash.

The en dash has limited utility. Known mainly to editors and printers, the en dash is used to indicate “to” when showing a range of dates or pages (pages 24–25), to indicate a pairing of things with equal weight (win–win outcome), or to express tension or difference (love–hate relationship).

But really, is anyone actually registering the length of that dash? And would anyone, other than a typesetter, care if I’d used hyphens instead in those examples? I don’t think so. In fact, if we had to jettison one punctuation mark, I’d vote for the en dash. We already have enough stress in this world without having to worry about the length of punctuation marks. 

Remember this: 
Hyphens and dashes have different uses. Learn to use them correctly, and you'll bring greater clarity to your writing.