When Should I Use a Hyphen?

Hyphens serve as very useful punctuation marks, acting like the glue that holds multiple concepts together. Em dashes (—) and en dashes (–) should not be confused with hyphens (-), even though they all look similar. Here’s a trick. Remember that the minus sign (–, en dash) should not be used to add words or parts of words together to form one idea. Instead, use the hyphen!

You’ll use hyphens in a number of different circumstances, but the reason remains the same. Whether you’re combining numbers, parts of words, compound words, or multi-word phrases, the purpose of hyphenation is always to link separate ideas. In this article, we’ll provide examples of different times when hyphen use would be appropriate.

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How to Hyphenate Numbers

When writing out the numbers twenty-one through ninety-nine, always use a hyphen. So, any number in between those two (21-99) requires a hyphen in order to be spelled properly. 

Examples:

  • Fifty-six
  • Thirty-two

You’ll also want to use hyphens to write fractions. And, whenever a number is used as an adjective, you should hyphenate the number in its entirety. 

Example:

  • I owe him one-third of my salary.
  • He ordered the two-and-three-quarters size.

Some style guides also recommend using hyphens to separate date ranges, timeframes, and ranges of that sort. Other style manuals suggest that an en dash would be better. While neither choice is incorrect, you should try to maintain consistency and use the same symbol every time. Be sure not to add spaces on either side of the hyphen. 

Examples with Hyphens:

  • 1998-1999
  • 10:40-10:45 p.m.
  • 10-15 grams

Examples with En-Dashes:

  • 1998–1999
  • 10:40–10:45 p.m.
  • 10–15 grams

Multiple hyphens should always be used when writing ages. As an exception to this rule, any time the word “years,” “months,” or “days” is written as a plural, you don’t need to hyphenate.

Examples:

  • The dog was a two-year-old. 
  • The dog was two years old. 

Compound Adjectives

Second-hand books and off-brand paper towels have something important in common. Yes, they’re both paper products. What else? Both of these descriptions make use of compound adjectives! These modifiers that consist of two or more words, even though they form a single adjective. Compound modifiers typically appear in a sentence before the noun they describe. When compound modifiers come after the noun, you generally don’t need to hyphenate (unless it’s a common phrase that’s always hyphenated for clarity).

Example:

  • I like second-hand books.
  • I buy books second hand.
  • She bought over-the-counter medicine.
  • She bought the medicine over-the-counter. 

In the last example, “over-the-counter” is a phase that’s almost always hyphenated. For that reason, it doesn’t matter whether the phrase comes before or after the verb—you’ll hyphenate it either way.

Compound Verbs

As with compound adjectives, compound verbs consist of two or more words strung together. Many times, people choose unusual, multi-word verbs to add humor to writing. With hyphenated words, a writer can turn a phrase that doesn’t normally describe an action into a verb.

Examples:

  • He spider-walked across the dance floor. 
  • She green-thumbed her way to greatness. 

Compound Nouns

Lots of everyday nouns are made up of multiple words, such as “United States” or “brown rice.” Sometimes, depending on the compound noun in question, the sentence won’t make sense without hyphenating those words. If you didn’t have a way to show that they should be linked together, a reader might place emphasis on the wrong syllable and have trouble understanding the meaning of your sentence. 

Example: 

  • Nancy has always been the class treasurer. 
  • Nancy has always been a detention-getter. 

In the first sentence, you don’t need a hyphen. In the second sentence, the phrase “detention getter” is unusual and might not be understood without the hyphen. 

Generally, proper nouns are not hyphenated.  As an exception to this rule, some people put a hyphen between two surnames to indicate when names have been combined. 

Example:

  • When I got married, I changed my name to Elizabeth Walker-Smith. 
  • Before that, my name was Elizabeth Walker.

Hyphenating Prefixes

Although most prefixes do not require a hyphen, some style guides recommend them for the following prefixes:

  • All-Knowing
  • Step-Mother
  • Great-Grandfather
  • Ex-Wife
  • Self-Employed

These suffixes are also frequently hyphenated:

  • Japanese-Style
  • President-Elect
  • Sodium-Free
  • Soy-Based

In addition to the examples listed above, many style guides recommend adding a hyphen for clarity in circumstances where you’d otherwise have a repeated letter or a proper noun without capitalization. 

Examples:

  • Interregional becomes inter-regional
  • Midjune becomes mid-June.

What to Do When You’re Unsure

Of course, the English language is always in a state of flux. A compound word that’s written with a hyphen today could become mainstream in the future. Once it’s commonly used and recognized, the compound may no longer require a hyphen. That’s what’s happened to compound nouns like “high school” and “ice cream.” Another example—for a long time, people spelled email with a hyphen (e-mail). Eventually, email evolved into the current accepted spelling. 

Whenever you’re unsure about whether or not to use a hyphen, refer to your favorite style guide. Often, within organizations, managers offer employees (or students) an organization-wide style guide so that everyone can see the preferred spelling for tricky compound words. For instance, a sneaker brand might require that employees, advertisers, and vendors write “fair-trade” with a hyphen. By alerting everyone to the company’s preferred spelling, the management team can maintain consistency across all branded materials.

Sources

  1. https://ophi.org.uk/wp-content/uploads/CMS_list.pdf
  2. https://owl.purdue.edu/owl/general_writing/punctuation/hyphen_use.html
  3. https://apastyle.apa.org/style-grammar-guidelines/spelling-hyphenation/hyphenation