What is the difference between "DE" and "DU"?

“DE” is a preposition. It is a preposition used a lot in many contexts. Generally, "DE" is used to indicate provenance or belonging.
 

For example :

  • Je suis de France. (Je viens de France.) = I'm from France.
  • C'est le livre de mon père. (Ce livre appartient à mon père.) = This is my father's book.
     

“DU” is the contraction of "DE" and "LE". It can be used for many things as well.
 

For example :

  • J'ai du travail à faire.= I have work to do.
  • C’est le chien du voisin. = It's the neighbor's dog. 
     

One very important thing to know to distinguish them is that they are not in fact opposite.
 

"DE" is formed from the preposition "DE" and still very important from the article DEFINED (remember this word well) "LE".
 

To distinguish between them and know when I'm going to use one or the other, you have to know the context, what you're saying and have all the elements of the sentence.
 

 ⚠️  Information importante :

"DU" is used before a masculine noun:

  • C’est le chien du voisin.

If the noun is feminine, we put "DE LA" :

  • C’est le chien de la voisine.

If the noun is in the plural, we put “DES” :

  • C’est le chien des voisins.

And when the name starts with a vowel, "DU" becomes "DE L'".

  • C’est le chien de l’homme en rouge.

 

How do I know if I should use "DE" or "DU"?

Let us observe these sentences:

  1. J’achète un billet de train.

  2. J’achète le billet du train N°123456.
     

In the first example, do we know which train I will take?
→ No.
 

In the second example, do we know which train I will take?
→ Yes, "le train N°123456".
 

 

We will use "DE" to designate something general or undefined.
 

“Un billet de train”. It could be any train, we don't have details on the train in question.
 

 

Whereas "DU" is often used to designate something more precise, more defined.
 

“le billet du train N°123456”. I know which train it is, it is defined. I have information about the train in question.
 

 ✅ Little tip :

Often when we use "un(e)" the noun will be undefined or general. In this case, I will use "de". : J’achète UN billet DE train.

And when I use "le" or "la", the name will be defined. In this case, I will use “du” : J’achète LE billet DU train N°123456.

 

 ⚠️  Warning :

“DE” can be used before a proper noun or pronoun that is defined.

For example:

  1. J’ai rêvé de Jules.
  2. J’ai rêvé du voisin.

In both sentences, it's defined, I know who I'm talking about. But still, I use in the first sentence “DE”. And yes, because Jules is a proper name and you can't put an article like “le, la or les” before. If I can't put an article "le, la or les" in front of it, I can't put "DU" in front. Because, you remember, "DU" is built with "le".

 

 ⚠️  Warning :

Look at this sentence:

Je mange du fromage. (I'm eating cheese)

I use "DU" when I have no additional or specific information about the cheese. And yes, because here I am using "DU" as a partial article that is used to express a non-quantifiable quantity.

It is important to note that these rules do not always apply in all cases. There are exceptions, such as in some idiomatic expressions, where "de" can be replaced by "du" or "des".

You must be attentive to the nuances of meaning, the exceptions and especially the context when using "de" and its contractions "du" and "des" in French.

 

In summary:

To know whether to use "DE" or "DU", you need to ask yourself:

  • What is the gender of the noun that follows (feminine or masculine)?
  • Am I talking about a quantity?
  • Am I talking about something definite or general?
  • Is the noun that follows a proper noun or is it a pronoun?

 

Practice :

Let's complete together these sentences between “DE” or “DU” :
 

First sentence:

C’est un chien __ berger.
 

First sentence:

 

What is the gender of the noun that follows (feminine or masculine)?
→ Masculine


Am I talking about a quantity?
→ No.


Am I talking about something definite or general?
→ It's general, I don't have any specific information about the berger (shepherd).


Is the noun that follows a proper noun or is it a pronoun?
→ No.
 

 

So, it's not a particular berger (shepherd). I'm talking in general. Also, I have a little hint before "chien", I use "un" which is an INDEFINITE article. I then see use "un".

C’est un chien DE berger.
 

 

Second sentence:

C’est le chien __ berger du village voisin.
 

What is the gender of the noun that follows (feminine or masculine)?
→ Masculine


Am I talking about a quantity?
→ No.


Am I talking about something definite or general?
→ It's definite, I know it's the shepherd in the next village.


Is the noun that follows a proper noun or is it a pronoun?
→ No.
 

 

I'm talking about a berger (shepherd) in general, I'm identifying him. Also, right before "chien", here I have a definite article "le". So I'm going to use "DU".
 

C’est le chien DU berger du village voisin.
 

 

Third sentence:

Il parle __ livre que j’ai écrit.
 

Fourth sentence:

J'ai besoin __ livre que tu as emprunté à la bibliothèque. 
 

Fifth sentence:

Elle est professeur __ mathématiques.
 

 

 Answers : 

J'ai besoin DU livre que tu as emprunté à la bibliothèque.(defined)

Il parle DU livre que j’ai écrit. (défini)

Elle est professeur DE mathématiques. (general)

 

 

See you soon for new adventures, in French, of course! 🇫🇷