A Versus An

Today's topic is "a" versus "an."

Mignon Fogarty,
February 3, 2011
Episode #261

A Versus An

Today's topic is a versus an.

A lot of people learned the rule that you put a before words that start with consonants and an before words that start with vowels, but it's actually a bit more complicated than that. For example, here's Matthew with a question:

I've been wondering if it is actually a hour or an hour. An hour sounds more correct, but a hour reads more correct. I'm just curious on what it should be.

The rule is  that you use a before words that start with a consonant sound and an before words that start with a vowel sound (1).

Should You Use a or an?

So to answer Matt's question, an hour is correct, because hour starts with a vowel sound. People seem to ask most often about words that start with the letters h and u because sometimes these words start with vowel sounds and sometimes they start with consonant sounds. For example, it is a historic monument because historic starts with an h sound, but it is an honorable fellow because honorable starts with an o sound. Similarly, it is a Utopian idea, but an unfair world.

The letters o and m can be tricky too. Usually you put  an before words that start with o, but sometimes you use a. For example, you would use a if you were to say, “She has a one-track mind,” because one-track starts with a w sound. Similarly, “She has an MBA, but chooses to work as a missionary.” 

Use a before words that start with a consonant sound and an before words that start with a vowel sound.

Other letters can also be pronounced either way. Just remember it is the sound that governs whether you use a or an, not the actual first letter of the word.

One complication is when words are pronounced differently in British and American English. For example, the word for a certain kind of plant is pronounced “erb” in American English and “herb” in British English. So the proper form in America is an erb, and the proper form in Britain is a herb. In the rare cases where this is a problem, use the form that will be expected in your country or by the majority of your readers.

Next: A Historic or an Historic?

A Historic or an Historic

While we’re talking about different pronunciations, let’s talk about a historic. Some Americans argue that it should be an historic, but I come down firmly on the side that says it should be a historic event. One of the most contentious interactions I had at a book signing was over this point.

Here’s my reasoning: If you have an odd accent for an American and pronounce historic as “istoric,” you can make an argument for writing an historic, but it’s a stretch since the standard American pronunciation of historic is with the h-sound: “historic.” So even if you pronounce it “istoric,” most of your readers won’t.

If you’re feeling argumentative about this point, I’ll direct you to Bill Walsh’s website, The Slot, which has an exhaustive review of how different style guides deal with historic. But you should know that after reviewing many style guides, he also stands behind a historic being the correct choice.

Definite and Indefinite Articles

A and an are called indefinite articles. The is called a definite article. The difference is that a and an don't say anything special about the words that follow. For example, think about the sentence, “I need a horse.” You'll take any horse—just a horse will do. But if you say, “I need the horse,” then you want a specific horse. That's why the is called a definite article—you want something definite. At least that's how I remember the names.


  1. Faigley, L. The Little Penguin Handbook. New York: Pearson Education. 2007, p. 255.

Additional Reading

Review by The Slot of "a" and "an" Before "Historic"

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