When to Use A vs. An | Difference & Example Sentences
- A is used before a noun that starts with a consonant sound (e.g., “s,” “t,” “v”).
- An is used before a noun that starts with a vowel sound (e.g., “a,” “o,” “i”).
Note that the rule is not whether they start with a consonant or vowel, but whether they start with a consonant or vowel sound. This can help you decide which to use in difficult cases like words beginning in “u” or “h.”
|Examples: A in a sentence||Examples: An in a sentence|
|He had a dog when he was a child.
Oranges are a good source of Vitamin C.
|She had an aneurysm when she was a child.
Many employees of the company owned an iPhone.
|A usurper to the throne was imminent.||Following an SOP is a good way to ensure everything goes smoothly.|
A or an before H
The rule of thumb for words beginning with “h” is to consider the way the word is pronounced. Words that have a silent “h” begin with a vowel sound, so they use “an.”
- For words where the “h” sound is pronounced, such as hat, hotel, or hard, use “a.”
- For words where the “h” is silent, such as honor, hour, or honest, use “an.”
A or an before U
Similarly, for words beginning with “u,” consider the way the word sounds.
- For words where the “u” sound is pronounced like “you,” such as user, usual, or utilized, use “a.”
- For words where the “u” sound is pronounced like “uh,” such as unusual, understanding, or utter, use “an.”
A or an before acronyms
The same rule applies to acronyms—say the acronym aloud to sound out whether it begins with a consonant sound or a vowel sound.
Some acronyms (like “NASA” [nass-uh]) are usually pronounced as full words, others (like “TV” [tee-vee]) by saying the individual letters. But remember that even the spoken form of a consonant can begin with a vowel sound (e.g., [em] for M, [aitch] for H).
- Acronyms beginning with a consonant sound use “a.”
- Acronyms beginning with a vowel sound use “an.”
Worksheet: A vs. an
Test your knowledge of the difference between “a” and “an” with these practice sentences. Fill in either “a” or “an” in each sentence.
Other interesting language articles
If you want to know more about commonly confused words, definitions, and differences between US and UK spellings, make sure to check out some of our other language articles with explanations, examples, and quizzes.
Frequently asked questions
- Is it “an historic” or “a historic”?
However, authorities disagree on whether “historical” should be preceded by “a” or “an.” Many dictionaries encourage you to use the indefinite article that suits your pronunciation (depending on whether you pronounce the “h” sound at the start of the word).
- Is it “an unique” or “a unique”?
- Is it “an hour” or “a hour”?
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