Devoir is the verb that does the work of half a dozen English modals. As a modal it expresses obligation (je dois partir — I have to leave), strong probability (il doit être malade — he must be sick), and, in the conditional, advice or moral obligation (tu devrais lui parler — you should talk to him). As a transitive verb it means to owe (je te dois cinquante euros). The conditionnel passé form j'aurais dû is the only natural French rendering of should have — a structure English speakers reach for constantly and need to internalize.
This page is the verb-reference entry: every paradigm, every compound tense, the major uses with examples, and the idioms. Use it as a lookup. The detail page covers the modal/transitive distinction and the deduction sense in greater depth.
The simple tenses
These are the tenses formed without an auxiliary — the basic conjugational paradigms. Devoir is highly irregular: like vouloir and pouvoir, the stem alternates across the paradigm.
Présent de l'indicatif
The present indicative shows the typical 3e-groupe stem alternation: a "strong" stem doi- / doiv- in the singular and 3pl, a "weak" stem dev- in the nous / vous forms.
| Person | Form | Pronunciation |
|---|---|---|
| je | dois | /dwa/ |
| tu | dois | /dwa/ |
| il / elle / on | doit | /dwa/ |
| nous | devons | /dəvɔ̃/ |
| vous | devez | /dəve/ |
| ils / elles | doivent | /dwav/ |
The 1sg / 2sg / 3sg are perfectly homophonous (/dwa/) — the spelling distinguishes them but the ear cannot. The 3pl doivent surfaces the underlying -v- that the singular forms hide.
Je dois partir, j'ai un train à prendre.
I have to go, I've got a train to catch.
Tu dois absolument lire ce livre, il est génial.
You absolutely have to read this book, it's amazing.
Ils doivent être coincés dans les embouteillages.
They must be stuck in traffic.
Imparfait
Built on the dev- stem (from nous devons) plus the regular imparfait endings.
| Person | Form |
|---|---|
| je | devais |
| tu | devais |
| il / elle / on | devait |
| nous | devions |
| vous | deviez |
| ils / elles | devaient |
The imparfait devait + infinitive often means was supposed to — a planned action whose realization is left open: on devait se voir hier (we were supposed to meet yesterday — and the implication is usually that we didn't).
Je devais l'appeler ce matin, mais j'ai complètement oublié.
I was supposed to call him this morning, but I completely forgot.
Le train devait arriver à dix-huit heures.
The train was supposed to arrive at six p.m.
Passé simple (literary)
Used in literary writing and historical narration. Note the circumflex on -ûmes / -ûtes. The stem is du-.
| Person | Form |
|---|---|
| je | dus |
| tu | dus |
| il / elle / on | dut |
| nous | dûmes |
| vous | dûtes |
| ils / elles | durent |
Il dut renoncer à son projet faute de moyens.
He had to give up his project for lack of resources. (literary)
Futur simple
The stem is devr- — the infinitive devoir loses its -oi- and the -r- doubles up against the futur ending.
| Person | Form |
|---|---|
| je | devrai |
| tu | devras |
| il / elle / on | devra |
| nous | devrons |
| vous | devrez |
| ils / elles | devront |
On devra changer de train à Lyon, c'est inévitable.
We'll have to change trains in Lyon, there's no way around it.
Conditionnel présent
Same devr- stem as the futur, with the imparfait endings. This is the form for "should" — the standard French equivalent of soft advice or moral obligation.
| Person | Form |
|---|---|
| je | devrais |
| tu | devrais |
| il / elle / on | devrait |
| nous | devrions |
| vous | devriez |
| ils / elles | devraient |
Tu devrais te reposer un peu, tu as l'air épuisé.
You should get some rest, you look exhausted.
On devrait peut-être réserver, c'est complet le week-end.
We should probably book — it's full on weekends.
Subjonctif présent
Highly irregular. The singular and 3pl use the doiv- stem; the nous / vous forms use the regular dev- stem. The pattern mirrors the indicative.
| Person | Form |
|---|---|
| (que) je | doive |
| (que) tu | doives |
| (qu')il / elle / on | doive |
| (que) nous | devions |
| (que) vous | deviez |
| (qu')ils / elles | doivent |
Je regrette que tu doives partir si tôt.
I'm sorry you have to leave so soon.
Impératif
The imperative of devoir exists but is essentially never used — telling someone "do your duty!" with dois ! would sound bizarre. We list it for completeness.
| Person | Form |
|---|---|
| (tu) | dois |
| (nous) | devons |
| (vous) | devez |
Participles and gérondif
- Participe passé: dû (masculine singular only — and the circumflex is critical, see below)
- Participe présent: devant
- Gérondif: en devant
The participle dû carries a circumflex on the masculine singular only to distinguish it from the partitive article du (du pain, du vin). The other agreed forms drop the circumflex: feminine singular due, masculine plural dus, feminine plural dues.
| Form | Spelling | Reason |
|---|---|---|
| m. sg. | dû | circumflex disambiguates from partitive du |
| f. sg. | due | no circumflex (no ambiguity) |
| m. pl. | dus | no circumflex |
| f. pl. | dues | no circumflex |
La somme due sera prélevée le 5 du mois.
The amount owed will be debited on the 5th of the month.
J'ai dû partir avant la fin de la réunion.
I had to leave before the end of the meeting.
The compound tenses
Devoir uses avoir as its auxiliary. Standard avoir + dû.
Passé composé
avoir (présent) + dû
The passé composé of devoir is one of the most-used verb forms in French. J'ai dû + infinitive expresses a one-time obligation that was acted on (= I had to) or, with a stative infinitive, a deduction about the past (= I must have).
J'ai dû annuler mon rendez-vous, ma fille est tombée malade.
I had to cancel my appointment — my daughter got sick.
Il a dû oublier, il oublie toujours.
He must have forgotten — he always forgets.
Plus-que-parfait
avoir (imparfait) + dû
J'avais dû partir avant la fin du concert.
I'd had to leave before the end of the concert.
Futur antérieur
avoir (futur) + dû
Il aura dû rentrer plus tôt que prévu.
He will have had to come back earlier than expected.
Conditionnel passé — j'aurais dû + infinitive
avoir (conditionnel) + dû
This is the most important compound form of devoir. J'aurais dû + infinitive is the only natural way to say should have in French. English speakers reach for this constantly — to express regret, second-guessing, advice given too late — and there is no other route.
| Person | Form |
|---|---|
| j' | aurais dû |
| tu | aurais dû |
| il / elle / on | aurait dû |
| nous | aurions dû |
| vous | auriez dû |
| ils / elles | auraient dû |
J'aurais dû t'écouter, tu avais raison.
I should have listened to you — you were right.
On aurait dû partir plus tôt, on va être en retard.
We should have left earlier, we're going to be late.
Tu n'aurais pas dû lui dire ça.
You shouldn't have told him that.
Subjonctif passé
avoir (subjonctif) + dû
Je suis désolé qu'il ait dû annuler son voyage.
I'm sorry he had to cancel his trip.
The core uses
1. Obligation: devoir + infinitive
The most frequent meaning. Je dois + infinitive = I must / have to.
On doit rendre le devoir avant vendredi.
We have to hand in the assignment by Friday.
Vous devez présenter une pièce d'identité à l'entrée.
You must show ID at the entrance.
The same construction in the imparfait often means was supposed to (planned but possibly not realized): on devait se voir hier mais j'étais malade.
2. Deduction: devoir expressing strong probability
Devoir + infinitive can also express what English does with must in its deductive sense: not "you are required to" but "the evidence says it's almost certainly the case."
Il doit avoir oublié notre rendez-vous.
He must have forgotten our appointment.
Avec ce vent, ça doit cailler dehors.
With this wind, it must be freezing outside.
Context distinguishes the two readings — the same form il doit partir can mean "he has to leave" (obligation) or "he must be leaving" (deduction). Most of the time it's clear which is intended.
3. Devrais — soft advice / should
The conditional devrais is the standard "should." Use it for advice, suggestions, gentle moral obligation. It is much softer than dois.
Tu devrais lui demander avant de prendre sa voiture.
You should ask him before taking his car.
On ne devrait pas juger sans connaître les faits.
One shouldn't judge without knowing the facts.
4. J'aurais dû — should have (regret)
The full past-counterfactual. Indispensable for talking about regret or second-guessing past decisions.
J'aurais dû prendre un parapluie, il pleut maintenant.
I should have taken an umbrella — it's raining now.
Il aurait dû te prévenir bien avant.
He should have warned you long before.
5. Devoir as a transitive verb: to owe
When devoir takes a direct object (a sum of money, a thing, a debt), it means simply to owe. No modal sense.
Tu me dois encore quinze euros pour le ciné.
You still owe me fifteen euros for the movie.
Je lui dois beaucoup, il m'a aidé dans un moment difficile.
I owe him a lot — he helped me through a hard time.
Comparison with English
Three friction points:
- Should and should have are both devoir in the conditional. English uses two different modal stacks (should / should have); French uses devrais and aurais dû. Internalize both as fixed forms.
- Must in English is ambiguous between obligation and deduction. French devoir is similarly ambiguous — context decides. Don't force a different verb for the deductive reading; il doit être malade covers both "he must (be obliged to) be sick" (rare) and "he must (probably is) be sick" (default).
- The participle is dû, not du. The circumflex matters. Du is the partitive article (du pain); dû is the participle. Without the circumflex on the masculine singular, sentences become genuinely ambiguous in writing.
Common Mistakes
Mistake 1: Using devoir in the present for should.
❌ Tu dois lui parler, c'est mieux.
Wrong register for advice — *dois* is too forceful, sounds like an order.
✅ Tu devrais lui parler, c'est mieux.
You should talk to him, it's better that way.
Mistake 2: Saying je dois avoir for should have.
❌ Je dois avoir pris un parapluie.
Wrong — *should have* is the conditionnel passé: *j'aurais dû*.
✅ J'aurais dû prendre un parapluie.
I should have taken an umbrella.
Mistake 3: Dropping the circumflex on the masculine singular dû.
❌ J'ai du partir tôt.
Wrong — without the circumflex, *du* is the partitive article. The participle of *devoir* needs *dû*.
✅ J'ai dû partir tôt.
I had to leave early.
Mistake 4: Adding avoir to the deductive reading where French uses present + infinitive.
❌ Il doit avoir être malade.
Wrong — French stacks *devoir* directly on the infinitive: *il doit être malade*. *Doit avoir* is only correct with a past participle: *il doit avoir oublié*.
✅ Il doit être malade.
He must be sick.
Mistake 5: Confusing the imparfait sense with the present.
❌ On doit se voir hier.
Wrong tense — past obligation/plan uses the imparfait *devait*, not the present *doit*.
✅ On devait se voir hier.
We were supposed to meet yesterday.
Key takeaways
Devoir is the verb of obligation, deduction, and debt. Four forms cover most modal needs: je dois (have to), je devrai (will have to), je devrais (should), j'aurais dû (should have). Lock these in as a ladder.
The paradigm has three stems: doi- / doiv- (singular present, 3pl), dev- (nous/vous, imparfait, infinitive base), devr- (futur and conditional). The participle is dû in the masculine singular only — the circumflex matters because it disambiguates from the partitive article du.
Two senses run in parallel: obligation (je dois partir) and deduction (il doit être malade). Context decides. As a transitive verb with a direct object, devoir simply means to owe — no modal sense.
For English speakers, devrais and aurais dû are the two forms to drill until they're automatic. Every "I should..." and every "I should have..." in your English thoughts has to come out one of those two ways in French.
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