What Are Hyphens Used For? A Guide to Using Hyphens in Writing

Hyphens are used at the word level in grammar. A hyphen isn’t part of sentence structure like end punctuation, dashes, or parentheses. 

Hyphens are used to create compound words and to provide clarity in the presence of compound modifiers preceding a noun. Hyphens have many uses to aid a reader’s understanding — and even more rules for writers to follow.

Review best practices on when to use a hyphen. Then, conveniently check your text for proper spelling, grammar, and punctuation with the Originality.ai Grammar Checker. 

What Is a Hyphen and What Is It Used For?

A hyphen is a short horizontal line (-); on a keyboard, it appears next to the number zero (0). 

Hyphens don’t indicate a break in thought like an em dash (—) does. They work within and between words to help provide clarity. Using a hyphen with a word is also referred to as “hyphenating” a word.

Hyphens Between Compound Modifiers Before a Noun

When there are two or more modifiers (adjectives or adverbs that modify or provide additional information) preceding a word, a hyphen can help to provide clarity in a sentence. 

Example (with modifiers: fast, talking):

• Correct: She is a really fast-talking salesperson 
• Incorrect: She is a fast talking salesperson. 

In the above example, the hyphen between the modifiers makes it clear that she is a salesperson who talks fast. 

Without the hyphen, she could just as easily be a talking salesperson who moves fast, which isn’t the intent and doesn’t make much sense. 

The two modifiers work together with the help of the hyphen.

Example (with modifiers: gluten, free, vitamin, rich):

• Correct: The gluten-free, vitamin-rich bread is good for you.
• Incorrect: The gluten free vitamin rich bread is good for you.

Without hyphens, the string of modifiers doesn’t have the correct structure to help a reader understand the sentence’s intended meaning. 

Hyphenating Modifiers Following a Noun

When a compound modifier appears after a noun, the hyphen is still necessary if it clarifies the sentence. If it doesn’t, it can be eliminated.

Examples:

• That is a well-known restaurant. 
  
  • The restaurant is well known.
• That is a fifteenth-century building.
  
  • The building was built in the fifteenth century.

However, hyphenation is often very important for a sentence’s meaning and clarity, even when the modifier appears at the end of a sentence:

• The wedding reception was family-style.
• The horror movie was spine-tingling! 
• They’re so self-aware.

How to know whether to hyphenate modifiers following a noun

Unfortunately, there is not one specific rule to memorize for whether a hyphen appears in a modifier after a noun. 

The best way to know whether to place a hyphen in these cases is to read the sentence with and without a hyphen and determine which is the easiest to read and understand. When in doubt, consult your style guide or a dictionary. 

Hyphens With Compound Modifiers Ending in -ly

As a general rule, most adverbs ending in -ly that are part of a compound modifier do not need a hyphen. 

Examples:

• She has a terrifyingly loud scream.
• He is a highly regarded physician.
• They are a happily married couple.
• The newly opened bakery has amazing scones!

Each of these examples has two modifiers, but they work together clearly without needing a hyphen.

Hyphenating Compound Nouns

Not all compound nouns require a hyphen, but many do. 

Examples:

• He drives a tractor-trailer.
• My sister-in-law is self-employed.
• The check-in counter is on the left.
• She runs cross-country.

Then again, many compound nouns don’t need a hyphen such as hot dog or coffee cup. The best way to know whether a compound noun is hyphenated is to check the dictionary. 

Hyphens With Ages as Modifiers

The age of a person (or thing) is hyphenated when it modifies a noun and precedes it, whether the age is written out or in numerical form:

Examples: 

• She is a 30-year-old woman.
• He has a two-year-old car.

When an age does not directly precede the noun, it can go without hyphens: 

Examples:

• The woman is 30 years old.
• His car is two years old. 

When an age is being used to represent a noun, it gets hyphens:

Examples: 

• The woman has a two-year-old.
• They dropped their 18-year-old off at college last week.

Hyphens and Prefixes

A prefix is a syllable attached to a root to add to or change its meaning. Examples of common prefixes include: pre-, de-, re-, anti-, ex-, self-, and un-, to name just a few. 

Words with prefixes are prevalent in our everyday language. In most cases, words with prefixes are not hyphenated.

Examples:

• I was unimpressed by the late assignment.
• I want to rearrange the room for a better interior design!

Then again, sometimes words with prefixes are hyphenated. The prefixes non-, semi-, and pre- are sometimes hyphenated. 

 Examples: 

• That contract is non-negotiable.
• The hair dye package says it is semi-permanent.

But not always:

• That was a preemptive decision.
• It’s the semiannual sale!

To add to the confusion:

Sometimes, a hyphen might help clarify the meaning of a word or differentiate two words that are spelled identically but mean different things (homographs, which are a type of homophone):

• I don’t walk for exercise, just for recreation.
• I had to start my painting over again! The re-creation took five hours. 
• I’d like to resolve the issue.
• I lost my homework. Now I need to re-solve all the math problems.
• They decided to resign from the position.
• Please re-sign that paper. 

While it is usually safe not to hyphenate a word with a prefix, there are many exceptions. The best way to know for sure is to check the dictionary. 

Hyphens and Numbers

Here are some examples of how hyphens are used with numbers:

• Spelled-out numbers from 21 to 99: thirty-two, sixty-eight
• Spelled out fractions: one-third, two-fourths
• Ratios or odds: 3-1, 50-1
• Ranges: 5:30-8:15 p.m., $40-$55 per hour, ages 9-17

Hyphens and Spelled-Out Words

If spelling out a word by the individual letters in writing, place a hyphen between each letter:

 Examples: 

• B-I-N-G-O
• “Don’t give them any C-A-N-D-Y. It’s too close to bedtime!”

Final Thoughts

Sometimes, hyphen use feels like second nature. We can tell when two modifiers need to be hyphenated because we can see the potential confusion without them. However, there are too many compound modifiers, compound nouns, prefixes, and exceptions to hyphen grammar rules to memorize them all. 

If you cannot easily tell whether a word or set of words needs to be hyphenated, consult a dictionary or review your text with a grammar checker.

Learn more grammar best practices in our top guides:

• Independent Clauses: A Complete Guide
• When to Use a Colon in Writing for Punctuation
• When to Use Quotation Marks