A4 vs au, What's the Difference?

Which to use

“A4” is a symbol and “au” is an article - they look or sound alike but fill different roles in a sentence.

#18,920
“A4” frequency rank: #24
“au” frequency rank: 18944
confusion score

Side-by-Side Comparison

Feature	A4	au
Definition	Format de papier de 210 mm × 297 mm.	Contraction de la préposition à et de l'article défini le.

Letter map: A4 vs au

Shared letters muted; letters that set A4 and au apart highlighted. Shared run: 1.

2 ch

Role in the sentence - A4 and au

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: A4 is asymbol and auanarticle. On the page they differ by a single letter - 4 in “A4” becomes u in “au”. Our composite confusion score for this pair is 18944, derived from the frequency rank of both members and their visual similarity.

A4 is recorded at frequency rank #18,920, classified as asymbol. au is at rank #24, tagged as anarticle, pronounced \o\.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 18944, this pair ranks #375,806 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of A4 vs au

Shared letters: a. Private to "A4": -. Private to "au": u.

"A4" · 1 letters · shape V · "au" · 2 letters · shape VV

Frequently Asked Questions

Is swapping "A4" for "au" ever safe?

No - they are not even the same part of speech. "A4" is a symbol and "au" an article, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "A4" or "au"?

"au" is the more common of the two: it sits at frequency rank #24 in our French list, against #18,920 for "A4". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Useful next steps

Pair "A4" vs "au" is on the table, pick a follow-up below.

Full dictionary entry for "A4" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "au" - compare definitions side by side with the headword page. Word entry
This pair ranks #375,806 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
"A4" and "au" also get mixed up with nearby pairs, the highest-scored neighbour is "A4 vs aur". Nearby pair

Confusion rank #375,806 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.