Fractions in French

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French Fractions

We use fractions (les fractions) to talk about parts of a whole. They are not just used in mathematics, but also in other day-to-day contexts such as recipes (e.g., ½ litre d’eauhalf a litre of water).

How to write fractions in French

Fractions that have the numbers 2, 3 or 4 as their denominators (e.g., 1/2, 1/3, 1/4, 2/3, 2/4, etc.) are irregular when they are written out or spoken. The numbers 5 and higher are expressed as ordinal numbers when they are denominators.

1/2 un demi 1/10 un dixième
1/3 un tiers 1/20 un vingtième
1/4 un quart 1/100 un centième
1/5 un cinquième 1/1000 un mllième

The word demi

When demi comes before a noun, we connect the two with a hyphen. In this context, demi does not change; it does not agree with the noun in terms of number or gender.

Examples:
un demi-litre d’eauhalf a litre of water (masculine)
deux demi-litres d’eautwo half-litres of water (masculine plural)
une demi-heurehalf an hour (feminine)

When demi comes after a noun, we place the conjunction et between the two. If the noun is feminine, we use demi in its feminine form (demie). Demi has no plural form; it agrees with the noun in terms of gender but not in terms of number.

Examples:
une heure et demiean hour and a half
une bouteille et demiea bottle and a half
trois heures et demiethree and a half hours
not: trois heures et demies

Plural fractions

If the numerator is higher than 1 and the denominator is higher than 2, we use the plural form of the denominator.

Examples:
2/3 → deux tiers
3/4 → trois quarts

Important French phrases with fractions

Check out the table below to avoid some typical mistakes:

Don’t say … Say this instead:
un quart d’année trois mois / un trimestrethree months
une demi-année six moissix months/half a year
trois quarts d’année neuf moisnine months/three quarters of a year
trois quarts des étudiants sont absents les trois-quarts des étudiants sont absentsthree quarters of the students are absent
à demi-prix à moitié prixhalf price
la demi-ville la moitié de la villehalf of the town