A vs an
Choose a or an based on the sound of the next word, not its spelling. Use an before a vowel sound (an apple, an hour, an MBA) and a before a consonant sound (a university, a one-way ticket, a European city). Silent letters and letter names are the main traps, because spelling and pronunciation disagree.
The rule
A vs an at a glance
A
An
- Rule
- Before a consonant sound
- Before a vowel sound
- Silent 'h' words
- a house, a hotel (h is pronounced)
- an hour, an honest mistake (h is silent)
- 'U'/'eu' words
- a university, a European, a uniform (start with the /j/ 'y' sound)
- an umbrella, an uncle (start with a true vowel sound)
- Letters and acronyms
- a NATO summit ('nay-toh', consonant sound)
- an MBA, an FAQ, an SOS (letter names starting with a vowel sound)
- Numbers
- a one-off event (starts with a 'w' sound)
- an eight-year-old (starts with a true vowel sound)
Which one do I need?
A or an?
Every answer at a glance
a
These words begin with a 'y' sound (/j/), which is a consonant sound, so they take a: a university, a European city.
This is a useful app for learning new vocabulary.
an
These words begin with a true vowel sound, the 'uh' in up, so they take an.
The test centre closed early for an unusual reason.
a
The h is pronounced, so the word starts with a consonant sound and takes a.
We stayed in a small hotel near the old harbour.
an
The h is silent, so the word really starts with a vowel sound and takes an: an hour, an honest answer.
Thank you for giving me an honest opinion of my essay.
an
Letter names like F (ef), M (em) and S (es) begin with a vowel sound, so the abbreviation takes an.
My cousin is an HR manager at a bank in Dubai.
a
Letter names like B (bee), P (pee) and U (yoo) begin with a consonant sound, so the abbreviation takes a.
I watched a BBC documentary about urban farming.
an
The word begins with a vowel sound, so use an. Numbers follow the sound too: an eight-week course, an 11-hour flight.
She found an affordable flat near the campus.
a
The word begins with a consonant sound, so use a. Most of the time the spelling tells you, because letter and sound agree.
He works for a large logistics company in Singapore.
a
One and once begin with a 'w' sound, which is a consonant sound, so they take a despite the vowel letter.
She signed a one-year contract with a tech start-up.
How to use a vs an
Why does sound decide 'a' or 'an', not spelling?
English chooses between a and an based on the sound at the start of the next word, not the letter it happens to be written with. Use an when that sound is a vowel sound, and a when it's a consonant sound, whatever the spelling looks like.
Most of the time spelling and sound agree, so a before consonant letters and an before vowel letters feels automatic. The rule only becomes visible (and only trips learners up) in the handful of cases below, where the first letter and the first sound disagree.
- She ordered an omelette for breakfast.spelling and sound agree, vowel letter, vowel sound
- He bought a bicycle for his daughter's birthday.consonant letter, consonant sound
The trickiest cases: silent 'h' and words starting with 'u'
A handful of words spelled with h actually begin with a vowel sound, because the h itself is silent: hour, honest, honour, heir. These always take an, even though the first letter is a consonant.
Words that start with the letter u cause the opposite problem: many of them (university, uniform, union, useful, European) actually begin with the consonant sound /j/ ('y' as in yes), so they take a, not an, despite the vowel spelling.
- It took her almost an hour to finish the assignment.silent h → vowel sound
- He wore a uniform for his first day at the new job.'uniform' sounds like 'yoo-niform' → consonant sound
- That's an unique way to solve the problem.→ a unique way; 'unique' starts with the /j/ sound
Letters, acronyms and numbers
Spoken letter names follow the same sound rule. F, H, L, M, N, R, S and X are all pronounced starting with a vowel sound ('ef', 'aitch', 'el', 'em', 'en', 'ar', 'es', 'ex'), so abbreviations that begin with them take an: an FAQ, an HR manager, an SOS.
Numbers behave the same way when spoken aloud: 'one' starts with a 'w' sound, so it takes a ('a one-way ticket'), while 'eight' and 'eleven' start with true vowel sounds and take an ('an eight-year-old', 'an eleven-hour flight').
- She's applying for an MBA at a university in Toronto.'M' is pronounced 'em'
- It's a one-in-a-million opportunity.'one' sounds like 'won', consonant sound
- We waited for a hour and a half at the immigration desk.→ an hour and a half
Common mistakes with a vs an
Find what is wrong in each one, then open it to check.
1She works for an university in Manchester.What's wrong? Show the fix
She works for a university in Manchester.
'University' begins with the consonant sound /j/ ('yoo'), so a is correct despite the vowel spelling.
2He waited for a hour before the doctor called him in.What's wrong? Show the fix
He waited for an hour before the doctor called him in.
The h in 'hour' is silent, so the word begins with a vowel sound and needs an.
3I need an USB cable for my laptop.What's wrong? Show the fix
I need a USB cable for my laptop.
'USB' starts with the letter U, spoken 'yoo' (a consonant sound) so a is correct.
4It was a honest mistake, so the teacher didn't deduct any marks.What's wrong? Show the fix
It was an honest mistake, so the teacher didn't deduct any marks.
The h in 'honest' is silent, so the word begins with a vowel sound and needs an.
5He has a MBA from a well-known business school.What's wrong? Show the fix
He has an MBA from a well-known business school.
The letter M is pronounced 'em', which starts with a vowel sound, so an is required.
6I'm looking for an one-bedroom flat near the station.What's wrong? Show the fix
I'm looking for a one-bedroom flat near the station.
'One' starts with a 'w' sound when spoken, so a is correct despite the vowel spelling.
Practise
Write your own
Write a sentence that uses a or an, about you, your studies or your town.
A vs an in IELTS
Speaking
- Article slips like 'an university' are among the fastest-noticed accuracy errors in Part 1; examiners hear the vowel/consonant mismatch immediately, even in an otherwise fluent answer.
- When you mention qualifications or job titles ('I have an MBA', 'she's a UN interpreter'), rehearse the sound aloud beforehand; abbreviations are the most common a/an trap in Part 3 discussions about work and study.
Writing
- In Task 2 essays about education or technology, 'a university degree' and 'an online course' are both common phrases; check the sound of the noun immediately after a/an, not of an adjective that comes between them (an outdated system, but a useful system).
- In Task 1, data commentary often needs a or an before numbers written as words ('an eighteen percent rise' vs 'a fifty percent fall'); say the number aloud to check its first sound before choosing the article.