Le Présent: Devoir (must / have to / owe)

Devoir is the verb of obligation, probability, and debt — three meanings woven together in a single irregular conjugation. It is the closest French gets to English must, have to, should, owe, and be supposed to. Of the four classic French modals (pouvoir, vouloir, savoir, devoir), devoir is probably the most semantically loaded: depending on tense, context, and the type of subject, it ranges from a parent's stern command (tu dois rentrer à minuit) to a hypothesis about reality (il doit être malade) to a literal financial debt (je te dois 20 euros).

This page lays out the three-stem paradigm with phonetic detail, walks through the three core uses (obligation, probability, debt), unpacks the obligation gradient (je dois / je devrais / j'aurais dû), explains why French uses the impersonal il faut alongside devoir, and previews how devoir in the passé composé is built with avoir.

The paradigm — three stems

Like pouvoir and vouloir, devoir uses three different stems in the present indicative:

The three stems are:

• doi- in the singular (je dois, tu dois, il doit) — pronounced /dwa/.
• dev- in nous/vous (nous devons, vous devez) — pronounced /dəv/, with a schwa.
• doiv- in 3pl (ils doivent) — pronounced /dwav/.

Unlike pouvoir and vouloir, which take the irregular -x ending in 1sg/2sg, devoir takes the standard -s, -s, -t endings. So je dois (not je doix) is correct.

Note the phonetic shift between singular /dwa/ and 3pl /dwav/: the v of the doiv- stem becomes audible in the plural because it is followed by silent -ent but pronounced before the consonant. The same alternation is the reason je dois and ils doivent sound distinct enough to disambiguate even in fast speech.

Use 1 — Obligation (with infinitif)

The first and most basic use: devoir + infinitive expresses obligation, duty, or necessity. It maps roughly to English must or have to, and unlike pouvoir, the obligation expressed by devoir is internal to the subject — the subject is the one bound to do the action.

The infinitive follows directly with no preposition. Devoir + de + infinitif is wrong in standard French.

The strength of the obligation is contextual. Tu dois rentrer à minuit (you have to be home by midnight) is a firm rule from a parent. Tu dois absolument essayer ce restaurant (you absolutely have to try this restaurant) is an enthusiastic recommendation. The same verb covers commands, requirements, and strong suggestions — register and adverbs distinguish them.

Devoir vs il faut

French has a parallel construction for impersonal obligation: il faut (it is necessary), from the verb falloir. The two often translate the same English sentence but differ in subject:

• Je dois partir. — I have to leave. (personal — the obligation is on me)
• Il faut que je parte. — It is necessary that I leave. (impersonal — the necessity is in the situation)
• Il faut partir. — One has to leave / We have to leave. (impersonal, no specific subject)

Il faut + infinitive is more general; il faut que + subjunctive is more pointed. Devoir is always personal and tied to a specific subject. In casual speech, je dois and il faut que je are often interchangeable; in formal speech, il faut que carries more weight.

Use 2 — Probability (inferential must)

Here is one of devoir's most distinctive features: the same verb that expresses obligation also expresses probability — the inferential must of English. Il doit être malade does not mean he is obligated to be sick; it means he must be sick (in the sense of I infer he is sick).

This double duty (obligation + inference) is exactly the same as English must, and it works the same way: context disambiguates. Tu dois rentrer with a stern tone is you have to come home; tu dois être fatigué is you must be tired. The verb is the same; the meaning shifts based on whether the action is something the subject performs (obligation) or a state the subject is in (probability).

The inferential reading is most natural with stative verbs (être, avoir, savoir) and least natural with active verbs. Il doit travailler could be either he has to work or, more rarely, he must be working — context decides.

Use 3 — Debt (financial or otherwise)

The third major use is the literal sense of to owe. This use is purely transitive — devoir takes a direct object (what is owed) and an indirect object (to whom):

The construction is devoir + [thing owed] + à + [person]. With pronouns, the indirect object pronoun (me, te, lui, nous, vous, leur) goes before the verb:

The non-financial extension — owing gratitude, an apology, an explanation — is just as common as the literal financial sense:

This use is purely transitive — there is no infinitive, no clause. It is the only one of devoir's three uses that does not involve a second verb.

Use 4 — Scheduled / supposed to (devoir + infinitif, future-leaning)

A subtle but important fourth use: devoir + infinitif can express something that is scheduled or supposed to happen — the be supposed to sense in English. Context makes the reading clear:

This is the meaning that overlaps with English be supposed to — a planned or expected event, not necessarily an obligation. The same construction can read either as obligation or as schedule, depending on whether the event is imposed (you have to) or merely expected (it's planned to).

The conditional — je devrais (should)

The conditional of devoir, je devrais (and the full paradigm), is one of the most useful forms in French. It expresses advice, recommendation, mild criticism, or moral obligation — corresponding to English should:

The stem devr- is irregular — it does not follow from the present forms. Memorize devrais as a unit; the rest follows from the standard conditional endings.

The shift from je dois (I have to) to je devrais (I should) is exactly the politeness/strength gradient learners need to master. Tu dois te reposer is a directive ("you have to rest"); tu devrais te reposer is a suggestion ("you should rest"). The conditional softens, advises, and recommends; the indicative commands and obligates.

The obligation gradient

Here is the full menu of devoir forms across tense and mood, each expressing a different shade of obligation:

The most common error: confusing je devrais (I should — present advice) with j'aurais dû (I should have — past regret). Both translate as should in English, but the first applies to present/future actions and the second to past actions you didn't take.

A note on the passé composé — j'ai dû

Although this page focuses on the present, learners often encounter the passé composé of devoir — j'ai dû — early on. Two things to know:

1. The auxiliary is avoir (not être): j'ai dû, tu as dû, il a dû, nous avons dû, vous avez dû, ils ont dû. There is no agreement with the subject.
2. The past participle dû takes a circumflex in the masculine singular only — to distinguish it from the partitive article du. The feminine due and plural dus, dues drop the circumflex.

The passé composé j'ai dû covers both English I had to (one-time obligation) and I must have (inferential past, equivalent to I must have done X):

This double duty in the past — actual obligation vs. inference — perfectly mirrors the present's double duty.

Common Mistakes

Mistake 1: Inserting a preposition between devoir and the infinitive.

Mistake 2: Using the present je dois for I should.

Mistake 3: Confusing je devrais with j'aurais dû.

Mistake 4: Using être as the auxiliary for devoir.

Mistake 5: Forgetting the circumflex on the masculine singular dû.

Mistake 6: Confusing devoir with il faut in subjunctive contexts.

Key takeaways

Devoir is the verb of obligation, probability, and debt — three meanings tied together by a single conjugation pattern. Its three-stem alternation (doi-/dev-/doiv-) parallels pouvoir and vouloir, but its 1sg/2sg endings are the standard -s (not -x).

The three core uses — obligation, inference, debt — all share the verb but differ in syntax: obligation and inference take infinitives; debt takes a direct object plus à + person. The conditional je devrais is the everyday word for should; j'aurais dû is should have; il faut que is the impersonal alternative for obligation.

Master these distinctions and you have unlocked one of French's most expressive verb networks. Devoir will accompany you through every register, from a parent's command to a stranger's polite recommendation, from a financial transaction to a philosophical inference about how things must be.