Forming plurals
Summary
Most French nouns form their plural by adding a silent -s, though several endings follow special patterns such as -eau → -eaux and -al → -aux.
Explanation
The regular rule is to add -s to the singular noun: un chat → des chats, une idée → des idées. This plural -s is normally silent, so in speech the plural is heard through the determiner (le/les, un/des, ce/ces) rather than the noun itself; in writing it is essential.
Three endings already finish in a sibilant and therefore take no extra mark: nouns ending in -s, -x or -z stay unchanged in the plural — le prix → les prix, le nez → les nez, la voix → les voix. Adding another -s here is a mistake.
Two ending groups take -x instead of -s. Most nouns in -eau and -eu add -x: un gâteau → des gâteaux, un jeu → des jeux (with rare exceptions like pneu → pneus). Most nouns in -al change to -aux: un cheval → des chevaux, un journal → des journaux — but a handful keep regular -s, notably bal → bals and festival → festivals.
There are also a few irregular plurals to learn by heart, such as un œil → des yeux and monsieur → messieurs. Rule of thumb: default to -s, leave words ending in -s/-x/-z alone, switch to -x for -eau/-eu and for -al → -aux, and remember the short exception list (bal, festival, pneu).
Examples
un chat, des chats — a cat, (some) cats (Regular -s (silent).)
le prix, les prix — the price, the prices (Ending in -s: unchanged.)
un gâteau, des gâteaux — a cake, (some) cakes (-eau takes -x.)
un cheval, des chevaux — a horse, (some) horses (-al becomes -aux.)
un festival, des festivals — a festival, (some) festivals (Exception: -al keeps regular -s.)
Common mistakes
des chevals
des chevaux
Most French nouns ending in -al do not take the regular -s in the plural; they change -al to -aux. So « un cheval » becomes « des chevaux », « un journal » becomes « des journaux ». Adding -s (« des chevals ») applies the default rule where it does not belong. Watch out, though, for a small set that keeps the regular -s: « un bal » → « des bals », « un festival » → « des festivals ».
Prerequisites
Related rules
numberpluralsnouns