Fractional quantities (la moitié de, le tiers de)

To express exact fractions in French, use specific nouns followed by the preposition de (of).

Remember to contract de with definite articles (de + le = du, de + les = des).

La moitié de (Half of)

Use la moitié de to express "half of." Notice how de and le tissu contract into du tissu.

The tailor cuts half of the fabric.
Le tailleur coupe la moitié du tissu.

Le tiers de (A third of)

Use le tiers de for "a third of." Before a demonstrative adjective like ce (this), de does not contract.

I would like a third of this fabric for the jacket.
Je voudrais le tiers de ce tissu pour la veste.
I adjust a third of the width.
J'ajuste le tiers de la largeur.

Le quart de (A quarter of)

Use le quart de for "a quarter of." Before a word starting with a vowel, such as un (a/one), de drops its vowel and becomes d'.

He measures a quarter of the length.
Il mesure le quart de la longueur.
The tailor cuts a quarter of a meter of fabric.
Le tailleur coupe le quart d'un mètre de tissu.