An official website of the United States government
Hyphens Part 2
We’re back with hyphens—there are just too many good tips to stop with just three. See Part 1 for our previous hyphenation advice. And check out the Resources section below for a list of exhaustive guides for this extremely useful but oft-misused piece of punctuation. Remember: We need hyphens! Working twenty four-hour shifts is not the same as working twenty-four hour shifts or twenty-four-hour shifts.
Hyphens connect words to make them more understandable. There are two types of dashes of different lengths:
- the en dash (–) is used for ranges
- the em dash (—) is probably what you think of when you think “dash”
En dash: The recipe calls for 1–2 teaspoons of salt.
Em dash: We’ll have the results of the tests soon—if the laboratory is open.
Hyphen: CDC just completed construction on a state-of-the-art laboratory building.
Don’t use en and em dashes interchangeably—see 4 Methods for Inserting a Dash in Word if you need help typing them.
*Note: do not use spaces on either side of a hyphen, en dash, or em dash.
Follow-up on the AIDS Vaccine
Long-term Effects of Radiation Exposure
En dash: The recipe calls for 1–2 teaspoons of salt.
Em dash: We’ll have the results of the tests soon—if the laboratory is open.
Hyphen: CDC just completed construction on a state-of-the-art laboratory building.
Patients have adverse reactions to the medication in one third of the cases.
A two-thirds majority is needed. (NOT two-third)
En dash: The recipe calls for 1–2 teaspoons of salt.
Em dash: We’ll have the results of the tests soon—if the laboratory is open.
Hyphen: CDC just completed construction on a state-of-the-art laboratory building.