Hyphenation Rules: When and How to Use Hyphens

Meet the Hyphen

Of the three little horizontal strokes English writers regularly mix up—the hyphen, the en dash, and the em dash—the hyphen is the shortest and, arguably, the most useful in everyday prose. See our rundown of punctuation marks for the whole family, and our side-by-side of en dashes and em dashes for the longer cousins. The hyphen has a single job: glue. Dashes pry clauses apart; the hyphen pulls word-parts together so a reader can see them as one idea.

What makes hyphens tricky is that the "right" answer shifts. A compound that needs a hyphen in one position may drop it in another. A word that was hyphenated in a 1995 stylebook may be a single solid word now. Dictionaries disagree. Newspapers do their own thing. Yesterday's data-base is today's database, and the same migration is happening to words you'd never think twice about.

The good news: most hyphenation decisions fall into a handful of patterns, and once you internalize those patterns you can handle ninety percent of cases without reaching for a reference. The sections below lay them out.

Compound Modifiers in Front of a Noun

If you remember one rule from this page, make it this one: when two or more words team up as a single adjective sitting in front of the noun they describe, hyphenate them.

• a deep-sea diver
• a last-minute cancellation
• a sugar-free drink
• a four-door sedan
• a six-year lease
• an off-the-shelf solution
• a hand-to-mouth existence
• a by-the-book supervisor

The hyphen tells the reader, "Treat these words as one unit." Drop it and strange readings creep in. Take heavy metal band—is the band heavy, or does it play heavy metal? Heavy-metal band removes the question. The same trick rescues phrases like light blue paint versus light-blue paint, or fast food chain versus fast-food chain.

Three or More Words Strung Together

When the modifier stretches to three, four, or even five words, hyphenate every gap so the string reads as one thought:

• a face-to-face meeting
• a dog-eat-dog industry
• a no-holds-barred debate
• a pay-as-you-go plan

When the Modifier Follows the Noun

Move the same compound to the other side of the noun—into predicate position—and the hyphens usually fall away. There is no longer a string of adjectives crowding the noun, so the reader isn't at risk of stumbling:

• The diver went deep sea exploring.
• Her cancellation was last minute.
• The drink is sugar free.
• He's been here six years.

A handful of compounds refuse to give up their hyphens no matter where they sit. These are the ones a dictionary lists as permanently hyphenated:

• The plan was half-baked.
• Her response came across as tongue-in-cheek.

Rule of thumb: if the compound has its own dictionary entry with a hyphen, keep the hyphen in every position. If it doesn't, the hyphen is probably just earning its keep in front of the noun.

Why -ly Adverbs Skip the Hyphen

Here is one place the rule is blissfully firm: do not hyphenate a compound modifier whose first word is an adverb ending in -ly.

• a brilliantly acted scene (not "brilliantly-acted")
• a densely packed crowd (not "densely-packed")
• a freshly baked loaf (not "freshly-baked")
• a nationally televised debate (not "nationally-televised")

The -ly ending is already a flashing signal that says, "I'm attaching to the next word." A hyphen on top of that is just noise. The exception is when -ly happens to end an adjective rather than an adverb. "Friendly," "lonely," "lovely," and "ugly" are adjectives that look like adverbs, so they still follow the normal hyphenation rule:

• an ugly-sounding rumor
• a lovely-smelling candle

Prefixes That Need a Hyphen

In general, prefixes slide straight onto their root word without punctuation: antiwar, nonstop, preheat, subtitle, superhero. A hyphen is reserved for the following situations.

When the Root Is a Proper Noun or a Number

• post-Shakespearean, pre-Columbian, pro-European, anti-Soviet, mid-1990s

The Prefix "Self-"

"Self-" keeps its hyphen almost without exception:

• self-taught, self-doubt, self-serving, self-reliance

"Ex-" When It Means "Former"

• ex-senator, ex-boyfriend, ex-roommate

Stopping Vowels or Consonants from Piling Up

• de-escalate (cleaner than "deescalate")
• co-op (not "coop," which is a chicken shelter)
• semi-independent

Keeping Two Real Words Apart

Sometimes a prefix plus a root spells out an unrelated word. A hyphen prevents the collision:

• re-press (press again) vs. repress (hold back)
• re-mark (mark again) vs. remark (a comment)
• re-lease (lease again) vs. release (let go)

Suffixes That Need a Hyphen

Suffixes tangle with hyphens far less often than prefixes do, but three patterns are worth memorizing:

• Attached to a proper noun: Dickens-esque, Kafka-like
• The honorific -elect: senator-elect, chairperson-elect
• When joining produces three of the same letter in a row: hull-less boat, cell-like structure

Spelled-Out Numbers and Fractions

Hyphens do steady work anywhere numbers get written out or combined with other words.

Two-Word Numbers from 21 to 99

Every compound cardinal and ordinal in that range takes a hyphen:

• twenty-three, forty-fourth, fifty-seven, seventy-two, eighty-ninth

Fractions Doing Adjective Duty

Hyphenate a fraction when it modifies a noun:

• a three-quarters vote
• a one-fifth stake

Numerals Plus Units of Measure

• a 12-ounce coffee
• a 500-word essay
• a 25-mile race
• a four-hour delay

The Shape-Shifting Compound Noun

Compound nouns come in three flavors—open (two separate words), hyphenated, or closed (one solid word)—and there's no clean formula for predicting which flavor any given compound uses. Convention, tradition, and sheer popularity decide.

With compound nouns the honest advice is: look it up. A current dictionary entry will tell you whether the word is currently open, hyphenated, or closed. Expect drift—compounds tend to start apart, pick up a hyphen as they become familiar, and eventually fuse into a single word.

Suspended Hyphens

When a sentence lists several compounds that share the same second half, you can leave the shared part off the earlier items and park a hyphen at the end of each. This is the "suspended hyphen":

• short- and long-range forecasts
• pre- and post-treatment scans
• two-, three-, and four-bedroom units
• 20- to 30-second clips

The space after each suspended hyphen matters. Write "short- and long-range," not "short-and long-range." The gap signals that a word has been temporarily borrowed from later in the sentence.

Hyphens That Rescue the Reader

A well-placed hyphen can stop a reader from misparsing a sentence on the first pass. Compare:

When you catch yourself pausing over a phrase, asking whether you've hyphenated "enough," flip the question: could a reader stumble here? If yes, hyphenate.

Ages, Colors, and Compass Points

Ages

Ages take hyphens when they act as modifiers or stand in as nouns, but not when they sit in predicate position:

• a three-year-old puppy (modifier before the noun)
• The three-year-old napped in the car. (used as a noun)
• My nephew is three years old. (predicate—no hyphens)

Colors

Color compounds get a hyphen when two hues blend into one, but stay open when you mean two separate colors:

• a grey-blue coat (a single blended shade)
• a grey and blue coat (two distinct colors on the garment)

Directions

Compass-point compounds vary: north-south corridor is hyphenated, northwest is closed, and west-southwest is hyphenated again because it pairs a simple direction with a composite one.

Why the Rules Keep Drifting

English compounds rarely hold still. A fresh compound typically enters the language as two open words, picks up a hyphen as it becomes familiar enough that writers want to bolt the parts together, then sheds the hyphen once the whole thing feels like a single word. A few trips through that life cycle:

• wire-less → wireless
• tomorrow was once to-morrow
• note-book → notebook
• data-base → database
• cell-phone → cellphone (still unsettled)

The practical consequence is that a rule your eighth-grade teacher enforced may no longer match current usage. When in doubt, consult a current dictionary and notice that British and American dictionaries don't always hyphenate the same words at the same time.

The Short Version

• Hyphenate a compound modifier that sits before a noun: "last-minute cancellation."
• Drop the hyphen when the modifier moves after the noun: "The cancellation was last minute."
• Never hyphenate after an -ly adverb: "a densely packed crowd."
• Use a hyphen with prefixes before proper nouns and numbers, with self- and ex-, and whenever one is needed to avoid colliding letters or ambiguous readings.
• Hyphenate spelled-out numbers 21 through 99 and fractions used as adjectives: "a three-quarters vote."
• Suspended hyphens tidy up parallel lists: "pre- and post-treatment scans."
• If a phrase could be misread without a hyphen, add the hyphen.
• Compound forms drift over time—trust a current dictionary over memory.

Keep going with our guides to em dashes, en dashes, and hyphens side by side, capitalization rules, and the full punctuation marks reference.