Gera Tools

French Plural Helper

-s/-x plurals, irregular ox→aux, and invariable words

Applies French plural rules to any noun or adjective: regular -s endings, -eau/-eu words taking -x, -al becoming -aux, the seven famous -ou exceptions, and invariable words ending in -s/-x/-z. Explains which rule fired.

What is the default French plural rule?

Most French nouns and adjectives form their plural by adding -s to the singular, for example chat becomes chats. This is the rule applied whenever no more specific ending or exception matches.

The French Plural Helper turns a singular French noun or adjective into its correct plural and tells you exactly which rule applied. French pluralisation looks simple — usually just add -s — but a handful of endings (-eau, -eu, -al, -ail, -ou) and several closed exception lists trip up learners. This tool encodes the real rules so you get the right form every time.

How it works

The tool checks your word against an ordered set of rules and stops at the first match:

  1. Already plural-stable. If the word ends in -s, -x, or -z, it is invariable and the plural equals the singular (souris → souris).
  2. -eau / -au / -eu → add -x. bateau → bateaux, feu → feux. Exceptions pneu, bleu, and landau/sarrau take a regular -s.
  3. -al → -aux, with the keep--als set (bal, carnaval, festival, récital, chacal, régal, cal, aval, naval, banal, fatal, final, natal).
  4. -ail → -aux for the seven nouns bail, corail, émail, soupirail, travail, vitrail, ventail; all others add -s (détail → détails).
  5. -ou → -s, except the seven -oux words bijou, caillou, chou, genou, hibou, joujou, pou.
  6. Default. Everything else simply adds -s.

Tips and example

For cheval the tool reports the -al → -aux rule and returns chevaux. For festival it recognises the keep--als exception and returns festivals. Capitalisation and a leading article are preserved where possible, so le chou becomes les choux. Note that proper nouns and many borrowed words (un sandwich → des sandwichs/sandwiches) have usage that varies; treat the result as the standard grammatical form and verify proper nouns separately.