There are three different ‘weights’, or sizes, of a dash. A hyphen (which we all know), an en dash and an em dash. An en dash gets its name from being the width of an ‘n’ (at least, historically). The em dash gets its name from being the width of, you guessed it, an ‘m’. Here’s what they look like, from shortest to longest:
En dash –
Em dash —
There is a lot of commentary on which to use, and when. But here’s the big idea: hyphens join up words, while dashes separate sentences or clauses.
So we use hyphens to make compound adjectives, things like ‘the wind-powered turbine’.
But you use a dash to make an aside (a parenthetical, in grammar jargon) or a connected sentence.
So you might say ‘the new car runs on diesel – that classic fuel – and will soon run electrically.’ Or you could say ‘we know you like fresh veg – so we started a garden.’
Read more about Hyphens here.
Use an en dash to separate out a phrase within a sentence – perhaps to break up the text, or add emphasis – instead of commas or brackets. You can also use a dash on its own to mark a break in a sentence – try it instead of a semicolon.
Always use an en dash, not a hyphen, in a range like 30–40 (only use dashes if you’re doing a range of figures – use ‘to’ for things like ‘Monday to Friday’). And for those ranges, don’t forget to take the spaces out from either side of the dash.
If you type in a hyphen to separate out a phrase within a sentence, Word will generally autocorrect it to an en dash. But sometimes you might need to put one in manually.
Em dashes aren’t used so much in the UK these days. They’re sometimes used instead of en dashes in the US to separate out a phrase (like this: ‘There was no way to make the words better—or was there?’). But our New York team don’t use it because they prefer the elegance of the en dash.