What is the Difference between the Hyphen, En dash and Em dash?

The hyphen, en dash, and em dash look similar but serve entirely different purposes. Confusing them is one of the most common formatting errors in academic manuscripts, partly because most keyboards only have a hyphen key, and many writers use it for all three.

This guide explains what each one does, when to use it in academic writing, and how to type each character correctly.

The Hyphen (-)

The hyphen is the shortest of the three. It joins words and parts of words. In academic writing, its main uses are compound adjectives before a noun (“a well-designed study,” “a peer-reviewed journal,” “a 10-year period”), prefixes in some cases (“pre-existing,” “co-author,” “non-native”), and compound numbers (“twenty-three”).

An important rule: compound adjectives are hyphenated when they come before the noun but not after. “A well-known theory” but “the theory is well known.” “A long-term study” but “the effects were observed over the long term.”

Some compound adjectives are always hyphenated regardless of position (check a dictionary). And some prefixes no longer require hyphens in modern usage: “nonnative,” “cooperate,” and “reexamine” are increasingly written without hyphens, though “non-native,” “co-operate,” and “re-examine” remain common in British English.

The hyphen is the key on your keyboard between 0 and =. No spaces around it.

The En Dash (–)

The en dash is wider than a hyphen and narrower than an em dash. It is named after the letter “n” because it is approximately the width of a typeset “n.” It has two primary uses in academic writing.

Ranges. Use the en dash for numerical ranges: pages 45–67, the years 2015–2023, temperatures of 20–25 °C, participants aged 18–34. No spaces around the en dash in ranges. The en dash replaces “to” or “through.” If you write “from 2015 to 2023,” do not use an en dash (“from 2015–2023” is incorrect because “from” requires “to”).

Connections between equal items. The en dash connects items that have equal weight or show a relationship: “the parent–child relationship,” “the north–south divide,” “a doctor–patient interaction,” “the Kuala Lumpur–Singapore corridor.” This differs from a hyphen, which joins unequal elements into a single compound word.

Some style guides (APA, for example) use the en dash instead of a hyphen in compound adjectives where one element is itself a multi-word term: “a New York–based company,” “a pre–World War II policy.” This prevents ambiguity about which words are grouped together.

To type an en dash: on Windows, press Ctrl+Minus (on the numeric keypad) or Alt+0150. On Mac, press Option+Hyphen. In Word, typing a space, a hyphen, and a space sometimes auto-corrects to an en dash, but this behaviour is unreliable.

The Em Dash (—)

The em dash is the widest of the three, approximately the width of a typeset “m.” It is used to insert a parenthetical remark, to add emphasis, or to set off a clause for dramatic effect.

“The results—surprisingly—showed no significant difference between groups.” “Three factors contributed to the outcome—sample size, measurement error, and timing.” In both cases, the em dash adds emphasis that commas or parentheses would not provide.

In academic writing, the em dash should be used sparingly. Many academic style guides discourage its use, preferring commas, parentheses, or restructured sentences instead. APA style, for instance, does not prohibit the em dash but recommends limiting its use. If you find yourself using em dashes frequently, consider whether commas or parentheses would be more appropriate.

There is no space around an em dash in American English (word—word). British English sometimes uses a spaced en dash (word – word) instead of an em dash. Check your style guide.

To type an em dash: on Windows, press Alt+0151 or Ctrl+Alt+Minus (numeric keypad). On Mac, press Option+Shift+Hyphen. In Word, typing two consecutive hyphens (–) without spaces sometimes auto-corrects to an em dash.

Quick Reference

Hyphen (-): Compound words, prefixes. “A well-known method.” No spaces.

En dash (–): Ranges and equal connections. “Pages 12–18.” “The cost–benefit analysis.” No spaces (or spaced in British style as an alternative to em dash).

Em dash (—): Parenthetical insertions, emphasis. “The results—contrary to expectations—were not significant.” No spaces (American), or replaced by spaced en dash (British). Use sparingly in academic writing.

Conclusion

The hyphen, en dash, and em dash are three distinct characters. Using a hyphen where an en dash is needed (or vice versa) is a formatting error that professional editors routinely correct. Knowing the difference takes five minutes. Applying it consistently makes your manuscript look polished and professional.

Want your formatting checked before submission? PM Proofreading’s journal editing service checks for correct use of hyphens, dashes, punctuation, and formatting conventions. Upload your manuscript and get a quote.

Further Reading

• A Quick Guide to Punctuation for Non-Native Researchers
• Overall English Grammar Review for Non-Native Researchers
• Capitalization Rules in English: A Guide
• 10 Proofreading and Editing Tips for Your Academic Writing

Frequently Asked Questions

When should I use a hyphen vs an en dash?

Use a hyphen to join compound words and prefixes (“well-known,” “pre-existing”). Use an en dash for ranges (“pages 12–18,” “2020–2024”) and connections between equal items (“the parent–child relationship”). A hyphen joins parts of a single term. An en dash connects two separate but related items.

Is the em dash appropriate in academic writing?

It is acceptable but should be used sparingly. Many academic style guides (including APA) recommend limiting em dash use. In most cases, commas, parentheses, or a restructured sentence can achieve the same effect more cleanly. If you are using more than one or two em dashes per page, consider alternatives.

How do I type an en dash and em dash on my keyboard?

For an en dash: Windows Alt+0150, Mac Option+Hyphen. For an em dash: Windows Alt+0151, Mac Option+Shift+Hyphen. In Microsoft Word, you can also use Insert > Symbol. Some word processors auto-correct two consecutive hyphens to an em dash, but this is not reliable across all applications.

Should there be spaces around en dashes and em dashes?

In American English, no spaces around either. “Pages 12–18” and “the results—surprisingly—were significant.” In British English, a spaced en dash (word – word) is often used instead of an em dash. Check your journal’s style guide for the convention they follow.