A and an are the same word in two shapes. The choice is not about the first letter on the page. It is about the first sound you say. A book, a car, a house all begin with consonant sounds. An apple, an orange, an egg begin with vowel sounds.
The trap is spelling. University starts with the letter u, but the sound is /juː/, a consonant sound, so it takes a. Hour starts with the letter h, but the h is silent, so the first sound is a vowel and the word takes an.
This page gives you the sound test, lists the letters and silent letters that cause trouble, covers acronyms, and finishes with a 20-question drill where every answer explains the rule.
The rule
The sound test
- Say the next word out loud and listen to the first sound.
- First sound is a vowel (/a/, /e/, /i/, /o/, /u/ sounds): use an. An artist, an umbrella, an idea.
- First sound is a consonant: use a. A table, a yellow car, a European city.
- The five vowel letters a, e, i, o, u usually make vowel sounds, so usually they take an: an apple, an elephant, an island, an orange, an umbrella.
Words that fool the eye
- University, user, useful, uniform and European begin with a /juː/ consonant sound, so they take a: a university, a useful book.
- One and once begin with a /w/ sound, so they take a: a one-hour class, a once-in-a-lifetime trip.
- Hour, honest and honour have a silent h, so they take an: an hour, an honest answer, an honour.
- Hotel and hospital do not have a silent h in standard English, so they take a: a hotel, a hospital.
Silent letters and vowel sounds
- A silent h turns a consonant letter into a vowel start: an heir, an hour.
- Letters that sound like a vowel name take an: an MP3 player, an LED screen, an X-ray.
- An abbreviation with a consonant name takes a: a UFO, a URL, a USB stick.
- When the sound is uncertain, say the phrase faster. Natural speech shows the real first sound.
A and an in sentences
- A and an go before a singular countable noun: a chair, an egg, a message.
- They introduce something new or one of many: "I saw a dog in the park."
- They also describe jobs and roles: "She is a nurse", "He is an engineer."
- They cannot stand before a plural or an uncountable noun. Say "books", "water" or "some books", not "a books".
Speed, emphasis and exceptions
- In fast speech, some words change their first sound. An historic is old-fashioned; most speakers today say a historic. Choose the spoken form you use.
- A before an abbreviation is decided by the letter name: an FBI agent, a BBC reporter.
- The article changes if the word after it changes: a hero, an honest hero.
- When you write, check the word directly after the article, not the whole sentence.
Examples
- She bought a book and an apple at the station.A before the consonant sound of book; an before the vowel sound of apple.
- He waited an hour for a bus.The h in hour is silent, so the first sound is a vowel. Bus starts with a consonant sound.
- My brother studies at a university in a European city.University and European start with the consonant sound /juː/, so both take a.
- We have a one-hour meeting every Monday.One starts with a /w/ sound even though it begins with the letter o.
- It was an honest mistake, so nobody was angry.The h in honest is silent and the first sound is a vowel.
- She is an engineer and her father is a pilot.Jobs take a or an, chosen by the first sound of the job word.
- I need an umbrella and a raincoat.Umbrella begins with a vowel sound; raincoat begins with a consonant sound.
- They stayed in a hotel near an old castle.Hotel has a pronounced h, so it takes a.
- He sent an MP3 file and a PDF document.The letter M has a vowel name, so MP3 takes an. P has a consonant name, so PDF takes a.
- That was a once-in-a-lifetime chance.Once starts with the consonant sound /w/.
Common mistakes
- Wrong: She is a engineer. Right: She is an engineer.
- Engineer starts with a vowel sound, so it takes an. Look at the sound, not the letter.
- Wrong: He waited a hour. Right: He waited an hour.
- The h in hour is silent, so hour begins with a vowel sound.
- Wrong: She studies at an university. Right: She studies at a university.
- University begins with the consonant sound /juː/, so it takes a.
- Wrong: I bought a umbrella. Right: I bought an umbrella.
- Umbrella begins with a vowel sound. The letter u is not always a vowel sound.
- Wrong: It was a honest mistake. Right: It was an honest mistake.
- Honest has a silent h, so the word starts with a vowel sound and takes an.
Practice drill
Answer all 20 questions. Each answer is marked at once, and the rule is explained under the question.
She bought ___ apple at the market.
Show answer and explanation
Answer: A. an Apple begins with a vowel sound, so the article is an.
He is ___ engineer for a large company.
Show answer and explanation
Answer: B. an Engineer begins with a vowel sound, so it takes an.
We waited ___ hour for the train.
Show answer and explanation
Answer: C. an The h in hour is silent, so the first sound is a vowel and the article is an.
My sister studies at ___ university in London.
Show answer and explanation
Answer: D. a University begins with the consonant sound /juː/, so it takes a.
I need ___ umbrella today.
Show answer and explanation
Answer: A. an Umbrella begins with a vowel sound, so the article is an.
It was ___ honest answer.
Show answer and explanation
Answer: B. an Honest has a silent h, so the word starts with a vowel sound and takes an.
They stayed at ___ hotel near the beach.
Show answer and explanation
Answer: C. a Hotel has a pronounced h sound, so the article is a.
He plays ___ one-hour match every Saturday.
Show answer and explanation
Answer: D. a One starts with the consonant sound /w/, so it takes a.
She sent me ___ MP3 file with the song.
Show answer and explanation
Answer: A. an The letter M is said with a vowel name, so MP3 takes an.
We watched ___ European film last night.
Show answer and explanation
Answer: B. a European begins with the consonant sound /juː/, so it takes a.
There is ___ old castle on the hill.
Show answer and explanation
Answer: C. an Old begins with a vowel sound, so the article is an.
He works as ___ pilot.
Show answer and explanation
Answer: D. a Pilot begins with a consonant sound, so the article is a.
I will be back in ___ hour or two.
Show answer and explanation
Answer: A. an Hour starts with a silent h and a vowel sound, so it takes an.
That is ___ useful website for learners.
Show answer and explanation
Answer: B. a Useful begins with the consonant sound /juː/, so it takes a.
She adopted ___ cat from the shelter.
Show answer and explanation
Answer: C. a Cat begins with a consonant sound, so the article is a.
He gave me ___ X-ray report.
Show answer and explanation
Answer: D. an The letter X is said with a vowel name, so X-ray takes an.
They live in ___ nice apartment.
Show answer and explanation
Answer: A. a Nice begins with a consonant sound, so the article is a.
We need ___ assistant who speaks Spanish.
Show answer and explanation
Answer: B. an Assistant begins with a vowel sound, so the article is an.
Please open ___ window.
Show answer and explanation
Answer: C. a Window begins with a consonant sound, so the article is a.
It took ___ hour to finish the form.
Show answer and explanation
Answer: D. an The silent h in hour leaves a vowel sound, so the article is an.
Drill complete
You answered every question.
Next topic: The or no article: general and specificTake the level test
Questions learners ask
Is the rule based on the written letter or the sound?
The sound. Say the word that follows the article and listen to its first sound. Vowel sound takes an, consonant sound takes a. Spelling only helps when the sound follows the letter, which is not always true.
Why is it "a university" but "an umbrella"?
University begins with the sound /juː/, which is a consonant sound, so it takes a. Umbrella begins with the pure vowel sound /ʌ/, so it takes an. Both words start with the letter u, which is why the letter is a bad guide.
Can I use "an" before an abbreviation?
Yes, and the same sound rule decides. Say the letters of the abbreviation: an X-ray, an MP3, an FBI agent use vowel-named letters, so they take an. A UFO, a URL and a BBC report use consonant-named letters, so they take a.
More grammar topics
The or no article: general and specific
The points to one specific thing. No article speaks about things in general. The difference changes the meaning of a sentence.
Prepositions of time: at, on and in
At marks a point on the clock, on marks a day, in marks a bigger period. The size of the time decides the preposition.
Prepositions of place: at, on and in
In puts something inside a space, on puts it on a surface, and at marks a point. The same object can take all three, depending on how you see it.
Take the free A1 to C2 level test to find your starting point.