C et G: doux vs dur

Two of the most common consonant letters in French — c and g — each represent two different sounds, and which sound you produce depends on a single rule: which vowel follows. Once you know the rule, you can correctly read hundreds of words you have never seen before. And once you understand the workarounds — the cedilla on c, the silent u after g, and the silent e in conjugations — you have a complete model of how French spelling handles these consonants.

This is foundational orthography. Without the c/g rule, you cannot reliably read garçon, mangeons, guerre, or aperçu. With it, you have a tool that pays off every day for the rest of your French life.

The basic rule, in one sentence

Before a, o, u, or any consonant, c and g are hard. Before e, i, or y, they are soft.

The reason French (and Spanish, Italian, Portuguese, English to a degree) carries this two-sound system for c and g is historical. In Late Latin, the consonants /k/ and /ɡ/ began to soften when followed by front vowels (/e, i, y/), eventually arriving at /s/ and /ʒ/ respectively in French. The spelling kept the original Latin letters; the pronunciation diverged. So cent (one hundred) is spelled with c but pronounced /sɑ̃/, while its cousin cant would be pronounced /kɑ̃/. The vowel does the work.

C: /k/ versus /s/

Hard c — /k/

Before a, o, u, or a consonant, c is /k/. Examples:

Soft c — /s/

Before e, i, or y, c is /s/.

The cedilla: ç forces /s/ before a, o, u

What if a French word needs a /s/ sound before a, o, or u — letters that would otherwise force the hard /k/? French solves this with the cedilla (la cédille), the small hook under c: ç. The cedilla is a pronunciation override: ç is always /s/, regardless of the following vowel.

The cedilla never appears before e, i, or y, because it would be redundant — c before those letters is already /s/. Writing çe or çi is a spelling error.

The cedilla appears most frequently in two contexts: certain noun roots (français, garçon, façon, leçon, façade) and the conjugations of -cer verbs (commencer, placer, avancer, prononcer) where the c needs to stay soft before endings starting with a or o.

G: /ɡ/ versus /ʒ/

The system mirrors c, with one extra wrinkle.

Hard g — /ɡ/

Before a, o, u, or a consonant, g is /ɡ/.

Soft g — /ʒ/

Before e, i, or y, g is /ʒ/. The /ʒ/ sound is the same as the s in English measure or pleasure.

The silent u: gu before e, i, y forces /ɡ/

What if a word needs a hard /ɡ/ before e, i, or y — vowels that would otherwise force the soft /ʒ/? French solves this with a silent u inserted between the g and the front vowel: gu before e/i/y is /ɡ/. The u is purely orthographic and is not pronounced as /y/ or /w/.

This silent u is also the explanation for the feminine forms of certain adjectives: long /lɔ̃/ (m.) → longue /lɔ̃ɡ/ (f.). Without the u, the feminine would be spelled longe and read /lɔ̃ʒ/, changing the consonant. The u preserves the hard g into the feminine form.

When gu appears before a or o, the u is generally pronounced (or at least written for etymological reasons) — Guadeloupe /ɡwa.də.lup/, jaguar /ʒa.ɡwaʁ/, aiguille /e.ɡɥij/. Don't generalize the silent-u rule to those positions.

The silent e: ge before a or o forces /ʒ/

The mirror trick: what if a word needs a soft /ʒ/ before a or o — vowels that would otherwise force the hard /ɡ/? French inserts a silent e between g and the back vowel: ge before a/o is /ʒ/, and the e is silent.

This is why -ger verbs (manger, nager, plonger, changer, voyager, partager) keep an e in their nous present-tense form (mangeons, not mangons) and throughout the imparfait singular and 3pl forms (je mangeais, tu mangeais, il mangeait, ils mangeaient). Without the silent e, the pronunciation would shift to /ɡ/.

A symmetry to remember

The two consonants form a clean four-way matrix:

Notice the asymmetry: c uses a diacritic (the cedilla) to switch direction, while g uses an inserted letter (silent u or silent e). There is no historical accident here — the cedilla is itself a fossilized small z, originally written as a separate letter. By the medieval period it had shrunk to the small mark we use today.

Why this matters for verb conjugation

The -cer and -ger verb groups are the highest-frequency place where this orthography matters. Without these tricks, every single one of the spelling-change -er verbs would shift consonant pronunciation between forms — which would not just be ugly but would make conjugation tables impossible to learn aurally.

Drill: read these aloud

Common Mistakes

Key takeaways

The c/g system is one of the cleanest spelling-to-sound rules in French. Hard before back vowels (a/o/u) and consonants; soft before front vowels (e/i/y). When the language needs to override the rule, it uses one of three devices: the cedilla ç (forcing soft c before back vowels), a silent u after g (forcing hard g before front vowels), and a silent e after g (forcing soft g before back vowels). Master these four positions — garçon, guerre, mangeons, cycle — and you can read aloud almost any French word with c or g on the first try.