A vs An Checker — Fix «a» and «an» by Sound
Paste your text and the checker flags every «a» or «an» that disagrees with the SOUND of the word after it — the rule article-less languages find hardest.
The rule: sound, not spelling
English chooses «a» or «an» by the sound of the next word, not its first letter. «An» goes before a vowel sound; «a» before a consonant sound. That usually matches the spelling — «an apple», «a book» — but not always. «University» starts with a vowel letter yet a «you» sound, so it is «a university». «Hour» starts with a consonant letter yet a silent h, so it is «an hour». This checker judges every «a»/«an» by sound and flags the mismatches.
Why this is hard if your language has no articles
Many languages — Chinese, Japanese, Korean, Russian, Polish and more — have no articles at all. Writers from those languages add «a», «an» and «the» from scratch in English, with no instinct to lean on, and the sound-based exceptions («a European», «an honest mistake») are exactly where the instinct would be needed most. The result is grammatically visible: «an university» or «a hour» reads instantly non-native even when everything else is perfect. Fixing these is one of the cheapest ways to make English read cleaner.
The exceptions worth memorising
Two short lists cover almost every trap. Vowel letter but «a» (a «you»/«wa» sound): a university, a European, a unit, a user, a one-time offer, a useful tip. Consonant letter but «an» (silent h): an hour, an honest answer, an honour, an heir. Everything else follows the plain rule. When you want the correction explained in your own language, or the whole sentence tidied, Diglot's grammar checker and paraphrasing tool pick up where this checker leaves off.
When to use a vs an: the rule is about sound, not spelling
The rule taught in most classrooms — «a» before consonants, «an» before vowels — is a shortcut, and it is the reason confident writers still get it wrong. The article is chosen by the sound that follows, not the letter.
That is why it is an hour, an honest answer and an MBA (the h is silent; M is read «em»), but a university, a European colleague and a one-off (all begin with a consonant sound — «yoo», «yoo», «wun»). Acronyms follow how you say them: an NHS trust if you spell it out, a NASA mission if you say it as a word. Writers whose first language has no articles at all — Russian, Chinese, Japanese, Korean, Polish — hit this hardest, because there is no instinct to fall back on and the spelling shortcut quietly fails.
Take it further with Diglot
This free tool runs in your browser. When you want to act on what it shows — fix the grammar, tighten the phrasing, or make your English read like a native wrote it — that is what Diglot is built for. The free tier is meaningful for daily writing, no card required.
Frequently asked questions
- When do I use a vs an?
- Go by the sound that follows, not the letter. «An» before a vowel sound: an hour, an honest answer, an MBA. «A» before a consonant sound even when the word starts with a vowel letter: a university, a European colleague, a one-off. Say the next word aloud and the choice is usually obvious.
- Why is it «an hour» but «a university»?
- Because «hour» starts with a silent h, so the first sound is a vowel, while «university» starts with a «yoo» sound, which is a consonant. The spelling points one way and the pronunciation the other — pronunciation wins.
- How does the checker decide a vs an?
- It reads the word after each «a»/«an» and judges its opening sound: a vowel sound takes «an», a consonant sound takes «a». It uses short exception lists for the well-known sound/letter mismatches (university, hour, European, honest…) and the plain vowel-letter rule for everything else.
- Will it handle «an MRI» or «an X-ray»?
- Letter-sound acronyms (an MRI, an FBI agent, an X-ray) are pronounced with a vowel sound, and this heuristic does not expand acronyms, so it may miss or mis-call them. Treat the tool as a fast first pass for ordinary words; acronyms you can check by saying them aloud.
- Is «a» or «an» ever a real choice?
- Rarely. A few words vary by accent (some say «an historic», most say «a historic»; «herb» is «an herb» in the US, «a herb» in the UK). Where usage genuinely splits, either can be correct — the tool follows the majority pronunciation.
- Is my text uploaded anywhere?
- No. The check runs entirely in your browser — your text is never sent to a server or stored. You can safely paste confidential or unpublished writing.
