Hyphen Rules and When to Use Them

Six Hyphen Rules With Examples

Understanding the rules is a lot easier when you can see them in action. These are the basic hyphen rules you need to follow, along with examples to show you how.

Rule 1: Use a Hyphen for Two-Word Modifiers Before Nouns

When a modifier consists of two words that join together to describe a noun, you need to use a hyphen. There are a few key things to keep in mind here:

• The two-word modifier needs to come before the noun.
• Both words need to function together to describe the noun.
• Neither word should be an adverb ending in “ly.”

It’s easier to understand this hyphen rule if you see it used. Check out these examples:

• I only eat grass-fed beef.
• The alley was full of hungry-looking cats.
• That is a dog-friendly campground.

Do not use a hyphen if the modifier comes after the noun or if the modifier contains an adverb ending in “ly,” as in these examples:

• The cats in the alley were hungry looking.
• The clearly upset teacher held the students after class.

Rule 2: Hyphenate Compound Words That Are Not Combined

Many compound words are combined or “closed” into a single word, such as “bookcase” and “racecar.” However, there are also many compound adjectives and words that are not combined, and these often use a hyphen to show they are related. Here are some examples of hyphenated compound words:

• free-for-all
• state-of-the-art
• check-in
• mother-in-law
• eye-opener
• editor-in-chief
• six-pack
• out-of-date

If you are unsure about whether a compound word is hyphenated, take a moment to look it up in the dictionary.

Rule 3: Use a Hyphen With Many Prefixes

There are three prefixes that nearly always require the use of a hyphen. Always use a hyphen with self-, ex-, and all-, as in these examples:

• The test was self-administered.
• My ex-husband was a computer programmer.
• My children believe I am all-knowing.

Also use a hyphen when the prefix ends with the same letter as the start of the root word:

• We should re-elect the mayor.
• Let’s conduct a meta-analysis of the research.
• It seems to me you’re expressing anti-intellectual sentiment.

In addition, you should always use a hyphen when a prefix comes before a proper noun, as in these examples:

• Some people might consider skipping the parade un-American.
• We will take a vacation in mid-August.
• That is a beautiful pre-Raphaelite painting.

Rule 4: Use a Hyphen With a Few Suffixes

Most suffixes don’t require a hyphen and simply join up as part of the root word. However, there are a few suffixes that need to be hyphenated, including -elect, -style, -based, and -free. You can see them in these examples:

• I love these restaurant-style tortilla chips.
• The mayor-elect will be present at the ceremony.
• It’s a good idea to avoid lead-based paints if at all possible.
• Our backyard is mosquito-free this time of year.

You should also use a hyphen when the suffix starts with the same letter or sound that ends the root word, as in these examples:

• The pitcher has a drip-proof lid.
• Her skirt had a bell-like shape.
• They followed a wheel barrow-wide path.

Rule 5: Hyphenate Compound Numbers and Fractions

Also use a hyphen in some situations involving numbers and fractions. You should always hyphenate compound numbers that you are spelling out, starting at twenty-one and ending at ninety-nine:

• At the age of twenty-one, I set out into the world.
• The car was going fifty-five miles per hour.
• There were ninety-nine bottles of beer on the wall.

Hyphenate all spelled-out fractions as well:

• Two-thirds of freshmen stayed in the dorms.
• This represents an increase of one-fifth of a percent.
• The sled is three and one-half feet in length.

Rule 6: Use a Hyphen to Avoid Confusion

If the word you are writing may be confusing without a hyphen, you should err on the side of adding one. You can see why a hyphen helps keep the meaning clear in these examples:

• The musician re-signed his contract.
• The musician resigned his contract.
  
• I re-sent the letter.
• I resent the letter.
  
• The group was made up of small-business owners.
• The group was made up of small business owners.

When to Use a Hyphen vs. a Dash

Understanding the difference between a hyphen and a dash can help you avoid common mistakes. Use a dash to show a break in the text, a range in dates or time, or to create emphasis. Use a hyphen to create a connection between two words.

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Practice Using Compound Words and Hyphens

Part of understanding how to use a hyphen involves studying compound words. Take some time to review with fun exercises for compound words so you can properly use a hyphen when the situation calls for one. It may take a little practice, but learning the basic hyphen rules will help you become a better writer. Like all aspects of English grammar, hyphen rules are there for a reason, and they also have some exceptions. Learn how to use a hyphen properly to make your writing more professional.