How to Say Fractions and Decimals in French: The Complete Guide

Whether you are following a traditional French pastry recipe, reading business reports, or discussing prices at a Parisian flea market, mastering numerical precision is essential. However, expressing fractions and decimals in French comes with nuances that frequently trip up English speakers: the decimal comma instead of a period, irregular words like tiers, and the tricky agreement of demi.

In this complete guide, we break down the rules, pronunciation habits, and real-life usage so you can speak French with confidence.

1. French Fractions: The Essential Rules

  • The numerator is a cardinal number (un, deux, trois...).
  • The denominator is an ordinal number (cinquième, sixième, dixième...).

    • Just like in English, a fraction consists of a numerator (the top number) and a denominator (the bottom number). The overall logic is identical:

However, French uses specific terms for the most common fractions.

The Core Irregulars

  • 1/2 = un demi (or la moitié as a noun meaning "the half")
  • 1/3 = un tiers
  • 1/4 = un quart
  • 2/3 = deux tiers (remains spelled tiers)
  • 3/4 = trois quarts

    • When the numerator is greater than 1, add an "-s" to make the denominator plural:

    Standard Fractions (From 5 and above)

  • 1/5 = un cinquième
  • 2/5 = deux cinquièmes
  • 1/8 = un huitième
  • 3/10 = trois dixièmes
  • 7/100 = sept centièmes
  • 1/1000 = un millième

    • For higher denominators, French uses regular ordinal adjectives:

> Pronunciation Tip: In spoken French, final consonants like the "s" in trois quarts remain silent unless followed by a vowel sound (trois quarts d'heure connects with a smooth /d/ liaison sound).

2. Navigating "Demi" vs. "Moitié"

One of the most frequent errors among French learners is confusing demi and moitié.

  • La moitié is a feminine noun that translates to "the half": « J'ai mangé la moitié du gâteau » (I ate half of the cake).
  • Demi functions primarily as an adjective or numerical qualifier.

    • Agreement Rules for "Demi"

1. Before the noun (joined by a hyphen), demi is invariable:

  • Une demi-heure (half an hour – no feminine "e")
  • Un demi-litre (half a liter)
  • Deux demi-journées (two half-days – no plural "s")

2. After the noun (linked with et), demi agrees in gender with the noun, but never takes a plural "s":

  • Une heure et demie (feminine singular)
  • Deux kilos et demi (masculine singular)
  • Trois semaines et demie (feminine singular)

    • 3. Decimals in French: Always Use a Comma (La Virgule)

In continental Europe and francophone countries, the separator between whole numbers and decimals is a comma (une virgule), never a period.

  • English format: `3.14`
  • French format: `3,14`

    • How to Pronounce Decimals

1. Reading numbers in pairs or blocks (everyday usage):

  • 0,5 = zéro virgule cinq
  • 1,25 = un virgule vingt-cinq
  • 8,75 = huit virgule soixante-quinze

2. Digit-by-digit reading (scientific or technical contexts):

  • 3,1415 = trois virgule un quatre un cinq
  • 0,02 = zéro virgule zéro deux

    • Price Conventions (Talking About Money)

  • 4,50 € = quatre euros cinquante (not quatre virgule cinquante euros)
  • 0,99 € = quatre-vingt-dix-neuf centimes
  • 12,20 € = douze euros vingt

    • When quoting prices, French speakers omit the word virgule entirely. Instead, place the currency where the comma sits:

    4. Percentages and Practical Measurements

Combining fractions and decimals with daily units:

  • Percentages: Read "%" as pour cent.
  • 20 % = vingt pour cent
  • 5,5 % = cinq virgule cinq pour cent
  • Kitchen measurements:
  • 500 g de sucre = un demi-kilo de sucre
  • 25 cl d'eau = un quart de litre d'eau

    • Quick Reference Cheat Sheet

    Number Written Form Key Rule
    :--- :--- :---
    1/2 Un demi Invariable before noun (un demi-verre)
    1/3 Un tiers Irregular base form
    1/4 Un quart Irregular base form
    3/4 Trois quarts Plural s on quarts
    1/6 Un sixième Standard ordinal form
    0,5 Zéro virgule cinq Use comma, pronounce virgule
    2,50 € Deux euros cinquante Currency replaces the comma
    1 h 30 Une heure et demie Feminine agreement on demie

By practicing these structures in cooking, budgeting, and routine discussions, you will eliminate hesitation and sound far more natural in everyday French interactions.