Hyphens are used to join words or parts of words so the meaning is clear. The most common uses are compound adjectives before a noun, spelled-out numbers from twenty-one to ninety-nine, and words with certain prefixes or built-in compound forms.

Common uses

  • Use a hyphen in compound adjectives before a noun: a well-known author , a one-way street.
  • Use a hyphen in spelled-out numbers: twenty-one , sixty-three.
  • Use a hyphen to avoid confusion: re-sign vs. resign.
  • Use a hyphen in some prefixes and compounds: ex-husband , self-employed , anti-inflammatory.
  • Use a hyphen in certain fractions and measurements: half-hour , three-quarter-mile.

When not to use one

  • Don’t use a hyphen just because two words are adjacent; many common compounds are now written as one word or as two separate words depending on dictionary and style guide preference.
  • Don’t confuse hyphens with dashes; they serve different punctuation jobs.

Simple rule of thumb

If two words act together like one adjective before a noun, a hyphen often helps: high-quality product. If removing the hyphen could make the sentence unclear, the hyphen is usually the safer choice.

Quick example

  • Correct: We bought a five-pound bag.
  • Correct: She is a well-known singer.
  • Correct: The bag weighs five pounds.