af vs au, What's the Difference?

Which to use

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

#14,405
“af” frequency rank: #24
“au” frequency rank: 14429
confusion score

Side-by-Side Comparison

Feature	af	au
Definition	De. Note d’usage : la préposition est suivie du datif.	Contraction de la préposition à et de l'article défini le.

Where the eye mixes af and au

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

2 ch

Why the eye confuses af with au

These two trip readers on the page rather than in the ear: af is \aːv\ while au is \o\. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - f in “af” becomes u in “au”, and the parts of speech differ too (preposition vs article), which is usually the fastest check. Our composite confusion score for this pair is 14429, derived from the frequency rank of both members and their visual similarity.

af is recorded at frequency rank #14,405, classified as aprep, pronounced \aːv\. 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 14429, this pair ranks #396,704 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of af vs au

Shared letters: a. Private to "af": f. Private to "au": u.

"af" · 2 letters · shape VC · "au" · 2 letters · shape VV

Frequently Asked Questions

Do "af" and "au" mean the same thing in a sentence?

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

Frequency check: "af" vs "au" - which ranks higher?

"au" is the more common of the two: it sits at frequency rank #24 in our French list, against #14,405 for "af". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

Eye-level mix-up between "af" and "au" is sorted above. Next: full entries or other pairs that share a letter shape.

Full dictionary entry for "af" 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 #396,704 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
"af" and "au" also get mixed up with nearby pairs, the highest-scored neighbour is "af vs aur". Nearby pair

Confusion rank #396,704 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.