Hyphens, En-dashes and Em-dashes

Hyphens, en-dashes and em-dashes are frequently used punctuation marks that are just as frequently misunderstood. All three marks are essentially horizontal lines, though their lengths vary (as do, occasionally, their designs – see figure 1). However, these three different marks have very different purposes, and using a hyphen to do an m-dash’s job is just as much of a punctuation error as using a question mark in place of a comma.

A hyphen is the shortest in length of the three. It is used to divide words that break at the end of a line, or to connect parts of compound words such as go-between, ill-fated and run-of-the-mill. The hyphen is easily found on the keyboard to the right of the zero.

An em-dash is the longest of the three, and is used to indicate a break in thought — as illustrated in this sentence. It can also be used to separate a thought within a sentence — such as this one — which would then require an em-dash at the beginning and the end of the phrase.

The en-dash, which is shorter than an em-dash and longer than a hyphen, is used to indicate a range of values, such as a span of time or numerical quantities (similar to using the words “to” and “from”); for example, 9 AM – 5 PM, Monday – Friday or ages 5 – 8.

Sometimes, for purely aesthetic reasons, a designer will use the en-dash in place of em-dashes throughout a document, or will add a small amount of space before and after either dash. These stylistic preferences are perfectly acceptable – consider them a form of artistic license! – and can be used to improve the color and texture of your type when the size and spacing of the em-dash is not to your liking. Just remember to be consistent throughout to avoid a jumble of varying styles.

One last tip: never use two hyphens in place of an em- or en-dash. This typographically incorrect practice is a holdover from typewriter days, when there were no dashes on the keyboard at all, just hyphens. Now there’s no excuse for this very un-dashing and unprofessional habit (figure 3, bottom).

• Editor’s Note:Ilene Strizver, founder of The Type Studio, is a typographic consultant, designer and writer specializing in all aspects of typographic communication. She conducts Gourmet Typography workshops internationally. Read more about typography in her latest literary effort, Type Rules! The designer's guide to professional typography, 4th edition, published by Wiley & Sons, Inc. This article was commissioned and approved by Monotype Imaging Inc.