Hyphen, En Dash, or Em Dash?

When to Use a Hyphen

Have you seen the meme touting irony, the one with the juxtaposed words hyphenated and non-hyphenated? I’ve seen it shared dozens of times on social media, and I’ve probably even smiled at it. The problem with that meme? Non-hyphenated does not require a hyphen. Nonhyphenated is correct. The use of a prefix (e.g., re- or non-) does not in and of itself necessitate a hyphen. Perhaps that’s the irony of the meme.

A Hyphen Has a Purpose: Clarity

One purpose (perhaps the main one) of a hyphen is to join compound words/phrases together; it provides clarity and tells the reader that these words go together as one phrase, as in the following examples:

• the fat-nosed man
• closed-toe shoes
• an open-and-shut case

In all of the above examples, the hyphenated phrases are adjectival (but not all hyphenated phrases will be adjectival!).

The phrase fat-nosed man means the man has a fat nose (and says nothing about his overall body size); fat nosed man, on the other hand, means that the man is fat (in the opinion of the writer, at least); it also specifies that he has a nose, which is a bit of a strange description but would, of course, depend on the rest of the context. Closed-toe shoes refer to shoes that cover the wearer’s toes; closed toe shoes, though, could refer to toe shoes (usually called Pointe shoes in ballet, I believe) that are closed (which seems to suggest that it would be difficult to get one’s foot into them). In any case, it should be clear that hyphens (or lack thereof) can affect meaning; using them correctly adds clarity and contributes to overall readability.  

Yes, readability and clarity. So, while prefixes (e.g., re- or non-) don’t generally require hyphens, there may be some cases where a hyphen is needed after a prefix for clarity. For example: re-creation versus recreation. Re-creation means creating again; recreation refers to a leisure activity.

• Hiking is one of my favorite forms of recreation. [Hiking is one of my favorite pastimes.]
• Hiking is one of my favorite forms of re-creation. [Hiking as reinvention (of self?)? Well, it could be, I suppose, but that’s likely not what the author intends.]

When to Use an En Dash

A hyphen is a pretty simple mark to insert into a document. On most keyboards, it’s located above the “P” key. I’d bet, though, that many people also use that same key for when they need to type an en dash (yes, I’ve done this myself). Depending on the context, MS Word may automatically create an en dash for you. And if you type two hyphens, MS Word usually translates that automatically into an em dash. But if (Windows-based) MS Word does not automatically create the correct dash for you, here’s what you can do:

The visual difference between the hyphen, en dash, and em dash should be clear. [Note: If using a Mac, there are different keyboard sequences to use.]

The name “en dash” originates from the dash being the approximate width of an “n” in typographic units. Similarly, the em dash’s name originates from it being the approximate width of an “M” in typographic units.

So, when do you use an en dash? You use it when you need to indicate through (or to), as in these examples:

• numbers 1–10 [numbers 1 through ten]
• open 10 am–2 pm [open 10 am to 2 pm]

Please note that you should not use an en dash to indicate to/through if the phrase starts with the words from or between. Instead, you should write out the word to (or through). Refer to the following examples:

• Incorrect: We’ll be open from 10 am–2 pm.
• Correct: We’ll be open from 10 am to 2 pm.
• Correct: The store’s hours: 10 am–2 pm.

When using the word between, an and should be used, as in this example:

We’ll be open between 10 am and 2 pm.

When to Use an Em Dash

An em dash can be used much like parentheses. Text within parentheses usually provides additional information; the same is true of text within two em dashes. All of the below statements are written correctly:

• My dog—a beautiful bichon mix named Rosie—likes to sunbathe on warm, sunny days.

• My dog (a beautiful bichon mix named Rosie) likes to sunbathe on warm, sunny days.

• My dog, a beautiful bichon mix named Rosie, likes to sunbathe on warm, sunny days.

In all of the above examples, the phrase “a beautiful bichon mix named Rosie” is an appositive (that is, it gives additional information about a noun or noun phrase), and the examples all show common ways to set off appositives.

An em dash can also be used in place of a colon (or semicolon, depending on the context; semicolons and colons, though, are not generally interchangeable). Check out the below examples:

1. We were all thinking the same thing at the end of the semester—freedom!
2. We were all thinking the same thing at the end of the semester: freedom!
3. I’m at the beach and have a good book to read—this is what summer is all about.
4. I’m at the beach and have a good book to read; this is what summer is all about.
5. I’m at the beach and have a good book to read: this is what summer is all about.

All of the above examples are correct. However, for #5, I find the use of the colon in that particular context a bit disruptive (although it’s technically correct). When there are two independent clauses, I’d prefer a semicolon. This, however, merely speaks to the stylistic flexibility (and subjectivity) of some punctuation rules. [Author’s note: Unfortunately, the blog platform (or perhaps the font being used) does not create as long of an em dash as I would like—I would prefer it to be more exaggerated for the purposes of explanation. If it looks like an en dash to you, please imagine it longer!]

Clear as Mud?

To be sure, this is not a comprehensive list of rules for hyphens, en dashes, or em dashes; this is merely a basic overview. The CMOS has pages and pages (and pages!) of hyphen rules, and even I find myself perplexed at times (and I’ve studied them at length). The rules of the hyphen are much more complex than most people probably realize. While en dash and em dash rules may be less complex, you still might find yourself saying, “Dash it all!” But if you don’t get anything else from this blog post, I hope you’ll remember this: A hyphen and a dash are not interchangeable!

Don’t worry if the rules seem elusive. Remember: You don’t have to write alone. I’m here to help. Feel free to leave a question in the comments, or contact me directly.