How to Conjugate the French Verb Devoir

The French verb devoir means "must," "to have to," or "to owe to." Essentially, it's used when you "have to" do something. Devoir is used very often in French and it has an extremely irregular conjugation that students need to memorize.

As with a number of French verbs, particularly the most useful ones, devoir can have different meanings. It is dependent on the context of the sentence and it can be confusing at times. Do not mistake the concept of "to have to" with the verb "to have" (avoir). The notion of "to have to" means an obligation to do something. In contrast, avoir implies the possession of something.

It's easy to confuse devoir with falloir, which also implies an obligation or necessity. Falloir tends to be more formal, so you can use devoir in sentences similar to these:

• Dois-tu étudier ce soir? > Do you have to study tonight?
• Elles doivent manger. > They must / need to eat.

Devoir can also take on the meaning of probability or supposition, such as:

• Il doit rentrer avant le dîner. > He should / will probably be back before dinner.
• Nous devons gagner plus cette année. > We should earn more this year.
• Elle doit être à l'école. > She must be at school.

There are times when devoir can refer to an expectation or intention:

• Je devais aller avec eux. > I was supposed to go with them.
• Il devait le faire, mais il a oublié. > He was supposed to do it, but he forgot.

You can also use devoir to express fatalism or the fact that something is inevitable:

• Il devait perdre un jour. > He had to / was bound to lose one day. 
• Elle ne devait pas l'entendre avant lundi. > She wasn't to hear it until Monday.

When used transitively (and thus not followed by a verb), devoir means "to owe":

• Combien est-ce qu'il te doit? > How much does he owe you?
• Pierre me doit 10 francs. > Pierre owes me 10 francs.

"Devoir" in the Infinitive Mood

The infinitive mood is devoir in its most basic form. The past infinitive can be used to modify another verb, so both are important to know. This is particularly true with a verb meaning "to have to," which can often be paired with other actions.

Present Infinitive (Infinitif Présent)
devoir

Past Infinitive (Infinitif Passé)
avoir dû

The indicative mood is the most common form of French verb conjugations. It states the verb as a fact and these should be your priority when studying. Practice them in context and concentrate on the présent, imparfait, and passé composé, which are the most useful tenses. Once you've mastered those, move on to the rest.

It's also strongly recommended to train with an audio source. There are many liaisons, elisions, and modern glidings used with French verbs and the written form may fool you into using a wrong pronunciation. 

In French, the conditional mood implies that there are no guarantees that the verb will actually happen. This is because the action of "having to" do something is dependent on certain conditions.

Cond. Present (Cond. Présent) -> Cond. Past (Cond. Passé)

• je devrais - > j'aurais dû
• tu devrais -> tu aurais dû
• il devrait -> il aurait dû
• nous devrions -> nous aurions dû
• vous devriez -> vous auriez dû
• ils devraient -> ils auraient dû

In the French subjunctive mood, the action of the verb is uncertain or in some way questionable. It's another common verb mood that has a few different forms.

You will find the various participle moods rather helpful as you continue your French studies. Be sure to brush up on the rules for using each form as well.

Present Participle (Participe Présent)
devant

Past Participle (Participe Passé)
dû / ayant dû

Perfect Participle (Participe P.C.)
Ayant dû

This is one of the few French verbs that have no imperative mood. You cannot conjugate devoir in the imperative verb form because it simply makes no sense to order someone, "Must!" 

Beyond those were previously discussed, there are a few more tricky situations surrounding devoir. For instance, you'll want to watch out for the masculine noun le devoir, which means "the duty" and les devoirs, which means "homework." These two can be the most confusing.

Devoir causes other problems in translation because it can mean should, must, ought to, have to, or supposed to. How do you know which to use when translating the word? The distinction between necessity and probability is not always clear:

• Je dois faire la lessive. > I should/must/have to do the laundry.
• Il doit arriver demain. > He is supposed to / should / has to arrive tomorrow.

To specify "must" rather than "should," add a word like absolument (absolutely) or vraiment (really):

• Je dois absolument partir. > I really have to go.
• Nous devons vraiment te parler. > We must speak to you.

To specify "should" rather than "must," use the conditional mood:

• Tu devrais partir. > You should leave.
• Ils devraient lui parler. > They should talk to him.

To say that something "should have" happened, use the conditional perfect of devoir plus the infinitive of the other verb:

• Tu aurais dû manger. > You should have eaten.
• J'aurais dû étudier. > I should have studied.

– Updated by Camille Chevalier Karfis.