The en and em dashes should not be confused with the hyphen: the en dash (–) is so called because it is as long as the letter n, and the em dash (—) is as long as the letter m. Both are longer than the hyphen (-).

The en dash is used:

  • To insert an extra phrase in a sentence
  • In number or year ranges, for example pages 125–30 and 2014–15
  • As a long hyphen, for example an English–Chinese dictionary

The em dash is used:

  • To insert an extra phrase in a sentence

Using a dash to insert an extra phrase in your sentence

Either an en or an em dash (but not a hyphen) can be used to insert an extra phrase in a sentence. In this use, an en dash should always have a space before and after. An em dash can be written either with or without spaces, but as always you should be consistent throughout your text.

Inserting an extra phrase in your sentence

Several British cities – Manchester and Glasgow for example – were important in the Industrial Revolution.
Several British cities — Manchester and Glasgow for example — were important in the Industrial Revolution.

Adding a pause for thought or emphasis

A dash can also be used to add a pause for thought or emphasis in your text:

The consequences were clear – war.
The consequences were clear—war.

Using a dash or dashes emphasizes an inserted word or phrase, while parentheses or brackets de-emphasize it or make it into an aside:

This is clear from Smith’s most recent work (see for example p. 10).
The consequences were clear (or so we were led to believe) – destruction in 45 minutes.

Number and year ranges

The en dash is also used in number and year ranges, for example:

pages 5–10
lines 1–50
Figures 3–5
1914–18
2015–2016

As a long hyphen

In contrast to the hyphen, the en dash links or juxtaposes two separate things rather than combining them into one, for example:

the London–Paris Eurostar
the North–South divide

In the example below, the first (with a hyphen) is a dictionary of Anglo-Saxon, the second (with an en dash) is an English and German dictionary:

an Anglo-Saxon dictionary
an English–German dictionary

And in the following example, the Smith-Jones process with a hyphen means a process by an author called Smith-Jones, e.g. Elizabeth Smith-Jones. In the second example the process is by two people, Smith and Jones (e.g. Elizabeth Smith and John Jones), and an en dash is therefore used:

the Smith-Jones process
(by Elizabeth Smith-Jones)

the Smith–Jones process
(by Elizabeth Smith and John Jones)