Here are the basics:
Use a before a word beginning with a sounded consonant:
- Sam always read a newspaper on the train.
- Gone With the Wind was a long movie.
Use an before a word beginning with a vowel sound:
- Mary thought Charlie was an egomaniac.
- We need an update to the contract.
Use an before a word beginning with an unsounded consonant:
- She billed me for an hour’s worth of work.
- It is an honor to be chosen for the award.
But what about those words in which you can hear the “h” sound, such as historic or hotel? Those words have an “aspirate h,” and the rule is this:
Use a with words that have an aspirate h:
- The Magna Carta is a historic document.
- Carrie preferred to stay at a hotel with a gym.
As for those words that begin with a vowel that is pronounced like a consonant, such as one, unit or university, keep this rule in mind:
Use a with a word beginning with a vowel that has a consonant-like sound:
- This is a one-time-only offer.
- A university education can go a long way.
Be mindful when using abbreviations and acronyms. For example, “M.B.A.” and “FBI” both begin with consonants, but you actually pronounce the letters themselves, which begin with vowel sounds. Therefore, you would use an.
- Terry earned an M.B.A.
- Jerry is an FBI agent.
However, if you would say or read the abbreviation or acronym beginning with a consonant-like sound, you would use a.
- Tom works for a European banking firm but is based in a U.S. branch.
- Pudgy swore he was stone-sober when a UFO flew over his house.
When dealing with numbers, it’s the same deal: Determine the pronunciation, and that will determine the correct article to use.