How to Use Dashes
Writers have three different dashes at their disposal: the hyphen, the en dash, and the em dash.
Most of us are familiar with hyphens and their uses. They’re used to form compound modifiers (such as in “a well-attended event”). We also use them to break a word that falls at the end of a line. This usage is becoming less common, however, because word processing and layout software programs typically have automatic end-of-line hyphenation features.
En and em dashes are less understood. The en dash is the width of a capital N (hence, its name). It’s used to indicate a range, as in the following examples:
For your homework, please read pages 162–195.
The meeting will be on Thursday, 4:00 p.m.–6:00 p.m.
The artist’s blue period, 1948–1952, was his most productive.
En dashes are also used to connect a prefix with an open compound:
post–World War II
The reason for using an en dash with such compounds is to send a subtle signal to the reader that the prefix belongs to the entire compound, not just the first word of it.
Em dashes are the width of (you guessed it) a capital M. Most often, they’re used in pairs to emphasize an element or elements within a sentence:
Cruciferous vegetables—broccoli, cabbage, and cauliflower, for instance—are said to lower the risk of cancer.
Em dashes can also show an abrupt change in thought:
I thought I had time—more than enough time—to catch the train.
Or they can show interrupted dialogue:
“I told you I can’t—”
“You mean you won’t, not can’t,” she said.
Many writers use a double hyphen in place of an em dash, and you might have noticed that your word processor sometimes will automatically turn them into an em dash. Most word processors have shortcuts for creating en and em dashes. It would be worth your while to search your help menu to find out what they are.
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22 Responses to “How to Use Dashes”
It would sound funny:
post-World War II if we use hyphen 🙂
I find that many clients have odd uses for en or em dashes. One is using an em dash after an italic run-in head followed by a period (and then the em dash.)
As a designer, I think there’s a better way of handling it than having double punctuation. I will get nowhere with this particular client. But are most punctuation guides pretty comprehensive? Meaning, that if they list examples, can one assume that any other uses are incorrect, and that if emphasis or pausing is needed, that it should be dealt with some other way?
It was a heartwarming story or It was a heart-warming story?
Sorry, the url kept getting truncated. Add the above to replace the ellipses in my two posts.
- Tom Connolly
Perhaps this reference work from 1912 will settle the matter defining the em:
Sorry, but slug is larger, i.e., taller, not as you say, “a good deal less than the height of the printed letter.”
Oops; I (obviously) meant “more than”, not “less than” there. What I’m saying is that even for 8/8 type, the cap height is a lot less than the height of the slug (i.e., less than 8 points). The Wikipedia article is defining an em as the full height of the slug, including leading!
I would have thought Adobe’s phrase, as you quoted, “It is more properly defined as simply the current point size,” would have ended the discussion, but it is clear that, for whatever reasons, the definition of an em and en has taken on different meanings since I learned it
But it’s Adobe’s definition that’s the new one (and not even correct according to Adobe’s own practice). Hence the further (older, more “correct”) references.
Oops. I just did the math 1302/18=72.3333333. 😉
Sorry, but slug is larger, i.e., taller, not as you say, “a good deal less than the height of the printed letter.” A slug contains the ledding (leading, if you prefer). An 8/9 or “8 on 9,” means 8-point type on a 9-point slug.
I would have thought Adobe’s phrase, as you quoted, “It is more properly defined as simply the current point size,” would have ended the discussion, but it is clear that, for whatever reasons, the definition of an em and en has taken on different meanings since I learned it, so I won’t belabor the poin… er, issue. I am pretty sure you have the Adobe point measurement reversed, too, because here I sit with my pre-Adobe pica pole (line gauge to typographers), and 18 inches is exactly 1302 points. But I’m sure this is getting wearisome for readers of this piece.
(i.e., a “point” in Adobe-speak is 1/72 of an inch, vs. 1/72.27 inch for a proper point)
Oh, sorry, I didn’t notice that you already pointed(ha!) that out…(though you seem to have gotten it the wrong way around)
Unless Adobe changed the definition
Adobe have done a few odd things in the past (i.e., a “point” in Adobe-speak is 1/72 of an inch, vs. 1/72.27 inch for a proper point), but I’m sure they haven’t changed this. FWIW:
Adobe’s online glossary: A common unit of measurement in typography. Em is traditionally defined as the width of the uppercase M in the current face and point size. It is more properly defined as simply the current point size. For example, in 12-point type, em is a distance of 12 points.
The TeXBook says: In olden days, an “em” was the width of an ‘M’, but this is no longer true; ems are simply arbitrary units that come with a font … the \rm font (cmr10) of plain TeX has 1 em = 10 pt …; the \bf font (cmbx10) has 1 em = 11.5 pt …; and the \tt font (cmtt10) has 1 em = 10.5 pt …. All of these are “10 point” fonts (i.e., the above “in 12-point type, an em is 12 points” is Adobe being bad!)
Wikipedia: One em is sometimes said to be equal to the width of a capital “M” in a particular typeface, as the “M” was commonly cast the full-width of the square “blocks”, or “em-quads” (also “mutton-quads”), which are used in printing presses. However, in modern typefaces, the character M is usually somewhat less than one em wide. [I note: this is why I said Times New Roman cap-height is only 0.65em; if you measure the “M” width, it’s closer to 0.80em—an “M” is rather less than an em wide…what the font calls an “em” internally, anyway: but if you ask for an “em” of horizontal space, you’ll get a space the width of an em-dash, which is also less than the “point size”, so it’s not sticking to its own definitions] Moreover, as the term has expanded to include a wider variety of languages and character sets, its meaning has evolved; this has allowed it to include those fonts, typefaces, and character sets which do not include a capital “M”, such as Chinese and the Arabic alphabet. Thus, em generally means the height of a font in question. (but note the “height” here is defined to be the height of the slug, a good deal less than the height of the printed letter)
Sorry Peter. Unless Adobe changed the definition, what I learned stands. An em is indeed a horizontal measurement. It is equal to the height of the capital letter–no ascenders or descenders. And an en is a half of an em. This horizontal measurement varies with the point size being used. This way it is always perfectly proportional no matter the point size of the type. I know Adobe changed the point, which used to be exactly 1/72 of an inch, so it may also have changed the measurement of the em and en, too.
I learned the meaning of em and en 50 years ago, when the newspaper where I worked used Linotype machines.
The “x height” of type varies widely by font, and it is generally held that the greater the x height the greater the readability.
Please cite your references.
An em is equal to the height of a capital letter.
No. An em is a unit of horizontal measure—it is, as stated, named after the letter “M”, of which it is nominally the width. Using it for vertical measure (the height of a letter) is a bit odd: font-size-relative vertical distances are usually measured in “ex” units (nominally the height of a lower-case “x”). An en is generally half an em, but not always. FWIW, the height of a capital letter is very unlikely to approach a full em (somewhere around 0.7 em is typical…e.g., the height of a capital letter in Times New Roman is 0.65 of its em width)
An em is equal to the height of a capital letter. And en is half that. The letters M and n, whether capital or not, don’t come into play.
Also, you might have mentioned that the double hyphen is a substitute for the em dash when the em dash key is unknown by the the writer.
Sean: yes; you shouldn’t space them.
Actually, let me restate that: you shouldn’t space them in text documents or your word processor…in properly typeset material, em dashes should be spaced with very thin, non-breaking spaces (less than a quarter of a normal inter-word space width; avoid getting a dash immediately before a line-break–or, worse, immediately after!)
The en dash is the width of a capital N (hence, its name).
Actually, it’s (nominally) the width of a lower case ‘n’.
Sean: yes; you shouldn’t space them. Some writers use spaced en-dashes instead of em-dashes…but don’t do that, either (in English; it’s normal in correct in some other languages)
Good reminders about some uses of dashes and hyphens. Thanks, Jacquelyn.
Let’s not forget using the en dash to connect two non-modifyng terms to a third, as in “the Wilson–Smith wedding.” (This has a “real” name, but it escapes me at the moment.)
Or the use of a hyphen to connect a prefix to a proper noun, as in “the anti-Washington rally.”
Or the use of a hyphen to indicate the use of a prefex when without it the prefix may create an unintended word, as in “recover” vs. “re-cover.”
BTW: When we type “word space hyphen space word,” Microsoft Word automatically converts the hypen to an en dash, though it leaves in the unnecessary spaces. Also, when we type “word hyphen hyphen word,” Word converts the two hyphens to the em dash. I am pretty sure these are the default conversion settings.
Interesting post. Again, thanks.
I have been placing spaces around both en dashes and em dashes. Is this incorrect?
That’s the way I’ve been using these three marks, with one exception. I didn’t know about using an en dash in place of a hyphen where the prefix refers to more than one word. I will have to keep it in mind for future writing. Thank you.
Sorry, I meant that comment for a different article. Please disregard!
How about the difference between immigrant and emigrant? I remember using both terms when I was in school and if I remember correctly, they have different meanings and are not interchangeable. Any thoughts?