Hyphens and dashes
Hyphens and dashes look similar, but they’re not interchangeable.
The hyphen ( - ) is the smallest of these marks. It has three uses.
- A hyphen appears at the end of a line when a word breaks onto the next line. These hyphens are added and removed automatically by your word processor’s hyphenation feature.
- Some multipart words are spelled with a hyphen (topsy-turvy, cost-effective, bric-a-brac). But a prefix is not typically followed with a hyphen (nonprofit, not non-profit).
- A hyphen is used in phrasal adjectives (commercial-speech restriction, estate-planning attorney, law-school grades) to ensure clarity. Nonprofessional writers often omit these hyphens. As a professional writer, you should not.
For instance, consider the unhyphenated phrase five dollar bills. Is five the quantity of dollar bills, or are the bills each worth five dollars? As written, it suggests the former. If you mean the latter, then you’d write five-dollar bills.
Dashes come in two sizes — the en dash and the em dash. The em dash ( — ) is typically about as wide as a capital H. The en dash ( – ) is about half as wide.
En and em dashes are often approximated by typing two or three hyphens in a row ( - - or - - - ). Don’t do that. Use real dashes.
The en dash has two uses.
- It indicates a range of values (1880–1912, 116 Cal. App. 4th 330–39, Exhibits A–E). If you open with from, pair it with to instead of an en dash (from 1880 to 1912, not from 1880–1912).
- It denotes a connection or contrast between pairs of words (conservative–liberal split, Arizona–Nevada reciprocity, Sarbanes–Oxley Act).
Be careful when citing a source like Local Rule 7-3. That gets a hyphen, not an en dash, because it’s the multipart name of a single rule, not a range of rules.