Dashes and hyphens

Dashes and hyphens aren't interchangeable. They can also create problems with translation and make content less accessible. For these reasons, it's best to limit their usage, especially within documentation and interface copy.

Never use an em or an en dash instead of a bullet in any kind of list.

Em dashes

In non-technical copy, you can use the em dash (—) sparingly when you want the reader to pause, to create parenthetical statements, or to emphasize specific words or phrases. However, you may find you can usually replace em dashes with parentheses or commas.

Always put a space on either side of the em dash. 

Where you're tempted to use an em-dash for emphasis in technical copy, try instead to front load the sentence with the important information.

 ✓ Click Enter, then exit the program. This ensures your work is saved.

 ✗  Click Enter, then exit the program—this ensures your work is saved.

Do not use em dashes to replace a colon in list introductions. 

To make one on a Mac: shift-option-hyphen.

En dashes

Use an en dash (–) to indicate spans of numbers, dates, or time. 

Do not put a space on either side of the en dash. 

 ✓  10:00–11:00 a.m. PT 

En dashes can connect compound adjectives in which each adjective is equally important and neither modifies the other.

 ✓  This year's APAC–EMEA conference will take place in August.

An en dash is also used when a multiple-word phrase is used as a modifier (bill of materials–based budgeting). However, such a complex construction could be difficult to translate, so avoid such phrases whenever possible.

To make one on a Mac: option-hyphen. 

Hyphens 

Use a hyphen (-) to make compound words. You can also use them to link prefixes or suffixes to the word they modify (always check the dictionary and word list). 

Do not put a space on either side of the hyphen.  

As a general rule, don't link prefixes (un-, multi-, post-) or suffixes (-ism, -ify) with a hyphen unless you can improve clarity with its inclusion. Readers will find co-worker much easier to read than coworker. However, cooperate doesn't present the same issue.

Some examples:  

• Prefix: co-branding

• Two-word phrasal adjective: list-formatted line item, hard-coded string

• Three-word phrasal adjective: off-balance-sheet accounting 

Note that if the phrasal adjective follows the noun, you don't need the hyphen (a well-known software company but that software company is well known). However, some fixed phrases such as cost-effective and old-fashioned are always hyphenated. Check the AP Style Guide for more nuanced guidance and Merriam-Webster(opens external page) for other examples of fixed phrases. 

Use a hyphen between numerals and units of measurementif the unit of measurement is not abbreviated (52-inch screen). However, if an abbreviation for the unit of measurement is present, discard the hyphen (You need 20 GB of free space).

A hyphen is not needed with very or with adverbs that end in -ly (recently saved model).

YesNo
very large data setvery-large data set
expertly constructed calculation expertly-constructed calculation
mostly ASCII charactersmostly-ASCII characters

Suspended hyphens

Suspended hyphens, also called suspensive hyphens, replace repeated words, prefixes, or suffixes in two or more compound modifiers (short- and long-term planning, first-, second-, and third-level models). 

Be careful with this usage, especially in technical content (and avoid whenever possible in interface copy). Consider your reader's literacy level and be mindful of adding complexity for translation. If in doubt, try to write the sentence in a simpler way.

Keyboard shortcuts / keyboard keys

When writing keyboard shortcuts using combination keystrokes, do not use hyphens to signify that the first key or keys should be held down while the last key is pressed. Use the plus sign (+) instead. (Don’t use the plus sign if each key should be pressed and released separately.) 

YesNo
Control+Shift+NControl-Shift-N
Esc N Esc-N; Esc+N

Prefixes that require hyphens

YesNo
all-inclusiveall inclusive
co-worker (but: cooperate; coordinate)coworker
cross-applicationcross application
ex-CEOex CEO
full-scalefull scale
high-levelhigh level
self-serviceself service

Prefixes that do not require hyphens

YesNo
counterclockwisecounter-clockwise
emaile-mail
multimediamulti-media
nonnegotiablenon-negotiable
onlineon-line
prerequisitepre-requisite
reassignre-assign
rewritere-write
semiconductorsemi-conductor
subtotalsub-total
underfundedunder-funded
websiteweb-site (or web site)

Common compound words that require hyphens

single-single-button, single-processor
high-high-level, high-quality
-sizemedium-size (never sized)
half-half-hour, half-length
to indicate locationlower-left corner, right-hand side of the screen
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