- A hyphen is a punctuation mark used to join words or parts of words.
- Hyphens are frequently used in compound modifiers when the modifier comes before the word it’s modifying.
- Hyphens are also used in compound words.
- A hyphen is often incorrectly used in place of an en dash (–) or em dash (—).
- Numbers between twenty-one and ninety-nine should be hyphenated when spelled out.
A hyphen is a punctuation mark used to connect words, creating compounds. Sometimes, a hyphen becomes a permanent part of the spelling of a compound term, no matter where the term is used in a sentence.
Other times, whether or not you should use a hyphen depends on how a compound functions grammatically in a particular sentence. Hyphens are extremely helpful, and they can also be confusing at times. Read on to learn more about when to use a hyphen and how to use a hyphen correctly.
Table of contents
Still not sure how to use a hyphen correctly?
What is a hyphen?
A hyphen (-) is a punctuation mark used to join words or parts of words, forming compounds. Hyphens are not interchangeable with dashes.
Hyphen vs. dashes
While a hyphen is used to join words or parts of words, forming compounds, dashes can be used to separate words, indicate ranges, and in some cases, indicate the connection between words. There are two types of dash: the en dash (–) and the em dash (—).
It can be easy to confuse a hyphen with a dash, as they’re all short horizontal lines between words. Here’s an easy way to tell the difference: a hyphen is the shortest, an en dash is longer, and an em dash is the longest. But despite their visual similarity, they play different roles in writing. Here’s a quick example:
- Hyphen: Thirty-six people came to the party.
- En dash: Thirty–six people came to the party.
The first example is correct, but the second one is not.
How to use a hyphen correctly
When a compound modifier, also known as a phrasal adjective, appears before the noun it is modifying, hyphens are often used between the words in the compound modifier to avoid ambiguity or the possibility of misreading.
For example, in the sentence The most-loved menu items are on the back, it is clear that most-loved refers to the items on the menu that are the most popular. Now, read it again without the hyphen: The most loved menu items are on the back. This could be saying that the back of the menu is where you’ll find the highest number of loved menu items. It’s ambiguous without the hyphen.
Check a dictionary to ensure you’re using hyphens correctly in a compound word; some compounds are hyphenated and some aren’t.
Hyphens in compound modifiers
Compound modifiers, also known as phrasal adjectives, are pairs or groups of words (of any part of speech) that join together to function as an adjective by modifying a noun. When a compound modifier appears before the noun it is modifying, it often makes sense to place hyphens between the elements of the compound to make the connectedness of the elements clear. When a compound modifier appears after the noun it is modifying, it should almost always stay open (unhyphenated).
Hyphens in compound modifiers before nouns
There is no grammatical rule that tells us exactly which compound modifiers to hyphenate before a noun and which ones to leave open. Instead, the rule is to hyphenate when doing so makes the sentence’s meaning clearer. Here are a few examples of hyphenated compound modifiers before nouns:
With two exceptions, it’s never grammatically incorrect to use hyphens in a compound modifier that appears before a noun. Those exceptions are when the first word of the compound modifier is an adverb that ends in -ly and when the compound modifier is a proper noun:
No hyphens in compound modifiers after nouns
No hyphen is generally needed if the noun comes before its compound modifier. Here are a few examples:
Hyphens in compound modifiers with participles
Compound modifiers that include present or past participles follow the same rules as any other compound modifier.
When we combine an adjective, a noun, or an adverb that doesn’t end in -ly with a present participle (the -ing form of a verb) to describe another word, we use a hyphen to clarify the combined descriptor’s meaning.
Without the hyphen between beautiful and looking, your reader may stumble over the sentence. Perhaps there’s a new type of daisy called the “looking flower”?
However, don’t use a hyphen when you are combining an adverb ending in -ly and a participle.
Compound modifiers that contain a past participle follow the same rules as other compound modifiers. Use a hyphen when the compound goes before the noun it modifies:
It’s unnecessary to use a hyphen when a compound modifier containing a past participle follows the noun it’s modifying.
Depending on which dictionary you use, you may find that it lists one of these phrases and calls for a hyphen. For instance, your dictionary may show “well-known” with a hyphen, implying that you should always spell it that way. You won’t be wrong if you use the hyphen, but remember the principle we just stated: it’s unnecessary.
Hyphens with high, low, and all
When using high or low as part of a compound modifier, use a hyphen when the compound comes before the noun it’s modifying.
When using all as part of a compound, use a hyphen if the compound is adjectival, whether before or after the noun it’s modifying, and leave the compound open if it is adverbial.
Hyphens in compound words
When a pair or group of words is used together frequently enough, it often becomes part of the general vocabulary in the form of a permanent compound. As time passes, many of these compounds continue to be spelled with hyphens between their component words.
However, some hyphenated compounds become closed compounds—teen-ager became teenager, for instance. Check a dictionary if you’re not sure how to spell a compound. Here are a few examples of common hyphenated compound words:
- Mother-in-law
- Half-pipe
- Ten-year-old
- Six-pack
- Foot-pound
- President-elect
Closed compound words
Hyphenated compounds tend to become closed compounds (single words with no spaces and no hyphens) over time. Email instead of e-mail, for example, is increasingly common. If you aren’t sure whether a word is a closed compound or a hyphenated one, check a dictionary.
- Notebook
- Halftime
- Waistcoat
- Fundraiser
- Chairperson
Open compound terms
Open compounds are spelled as two or more words separated by spaces. If you look up a compound and it isn’t in the dictionary, that means it should be open.
- Living room
- Real estate
- Dinner table
- Home base
Phrasal verbs vs. compounds
Phrasal verbs are two or more words—usually a verb plus a preposition—that together act as a completely new verb with a meaning separate from those of the individual words. Phrasal verbs are not hyphenated. Here are some examples of sentences using phrasal verbs:
Often, phrasal verbs have noun and/or adjective forms that are compounds, and many of those forms are hyphenated (or closed). Take care not to add a hyphen to a phrasal verb because its corresponding compound noun or adjective has one—this is a common error.
Here are some example sentences using the compound noun forms of the phrasal verbs from above:
Hyphens in numbers
Numbers between twenty-one and ninety-nine should be hyphenated when they’re spelled out, no matter what function they’re performing in a sentence.
Spelled-out two-word simple fractions are also hyphenated. However, one-word simple fractions (such as half and quarter) as part of a compound are not joined by hyphens to the other word or words of the compound in its noun form.
Hyphens in compound modifiers involving numbers
When a number appears as the first part of a compound modifier that comes before a noun in a sentence, the compound modifier is hyphenated. This applies whether the number is spelled out or in numerals and whether it is cardinal or ordinal.
However, a hyphen is not required if the number is the second word in a compound adjective.
Hyphens are also not used between a number and the word “percent” appearing before a noun.
Hyphens in compound modifiers involving fractions
When a fraction (e.g., half or quarter) is used as part of a compound adjective appearing before a noun, it should be hyphenated.
The word half also combines with other words to form compounds in nonmathematical contexts. These compounds are generally hyphenated when they are used as adjectives (before or after a noun) and open when they are used as nouns or verbs.
Hyphens with prefixes
Hyphens are occasionally used after prefixes to separate doubled letters or syllables that might be confusing or easy to misread otherwise:
- co-op
- anti-inflammatory
- re-creation (for the act of creating something again)
Use hyphens between prefixes and capitalized words or numerals:
- pre-1970
Always use a hyphen with the prefix ex- (meaning former).
Always use a hyphen with the reflexive prefix self-.
Capitalizing hyphenated words
When a hyphenated word appears at the start of a sentence, capitalize only the first word. Here are two examples:
Whether you capitalize a hyphenated word or words in a title depends on the style guide you’re using. Chicago, MLA, and APA style typically recommend capitalizing words after hyphens, per the same principles as other words in the title.
If you’re following a different style guide, this may or may not be the case, so always check before you submit your work.
Still not sure how to use a hyphen correctly?
Generally, use a hyphen to create a compound modifier if it comes before the noun it modifies, and use hyphens in a permanent compound if the dictionary lists it as spelled that way. Hyphens also appear in numbers, fractions, and, occasionally, words that include prefixes.
Using hyphens correctly shows that you take your writing seriously and want the work that you submit or publish to be polished. If you’re not sure if you’re using a hyphen correctly, use Grammarly Editor to check your writing. Grammarly catches mistakes and makes helpful suggestions that can help you write more confidently.
When to use a hyphen FAQs
When should you use a hyphen?
Use a hyphen to join words or parts of words.
Do you hyphenate numbers?
Hyphenate numbers between twenty-one and ninety-nine when spelling them out. Hyphenate two-word simple fractions like one-third when spelling them out.
Can hyphens and dashes be used the same way?
No. While hyphens join words, dashes are used to separate words and indicate ranges.
Can I use a hyphen instead of a colon?
No. A hyphen is not interchangeable with a colon.
