Devoir (must/to have to) in French

Overview

The verb devoir (must / to have to) completes the trio of essential French modal verbs, alongside pouvoir (can) and vouloir (to want). At the A1 level, devoir gives you the ability to express obligation, necessity, and duty — fundamental concepts for talking about rules, responsibilities, and daily tasks.

Like the other modal verbs, devoir features a stem change: doi- in the singular, dev- in nous and vous, and doiv- in ils/elles. It is followed by an infinitive when expressing obligation. An important secondary meaning is "to owe" (money or something else), which uses the same conjugation but takes a direct object instead of an infinitive.

In different tenses, devoir takes on nuanced meanings: in the conditional (je devrais), it means "should"; in the imperfect (je devais), it can mean "was supposed to." Even at the A1 level, being aware of these shifts helps you understand native speakers.

How It Works

Present Tense Conjugation

Subject	Conjugation
je	dois
tu	dois
il / elle / on	doit
nous	devons
vous	devez
ils / elles	doivent

Meanings and Patterns

Pattern	Example	English
Obligation	Je dois étudier.	I must study.
Necessity	Tu dois manger.	You have to eat.
Probability	Il doit être fatigué.	He must be tired.
Owing	Je te dois dix euros.	I owe you ten euros.
Advice (conditional)	Tu devrais dormir.	You should sleep.

Examples in Context

French	English	Note
Je dois partir.	I must leave.	Obligation
Tu dois faire tes devoirs.	You have to do your homework.	Duty
Il doit travailler demain.	He has to work tomorrow.	Schedule
On doit respecter les règles.	We must respect the rules.	Rules
Nous devons arriver à l'heure.	We must arrive on time.	Punctuality
Vous devez signer ici.	You must sign here.	Instruction
Ils doivent payer avant vendredi.	They must pay before Friday.	Deadline
Je te dois combien ?	How much do I owe you?	Money
Elle doit être malade.	She must be sick.	Probability
Tu ne dois pas toucher ça.	You must not touch that.	Prohibition

Common Mistakes

Confusing "devoir" (obligation) with "devoir" (homework)

• Wrong: Je fais mon devoir. (thinking it means "I do my obligation")
• Right: Je fais mon devoir. = I do my homework. / Je dois étudier. = I must study.
• Why: The noun un devoir (plural: des devoirs) means homework or duty. The verb devoir means must/to have to. Same root, different functions.

Forgetting the stem change in "ils doivent"

• Wrong: Ils devent partir.
• Right: Ils doivent partir.
• Why: The ils/elles form uses doiv-, not dev-. This parallels the stem changes in pouvoir and vouloir.

Using "devoir" when "falloir" is more natural

• Wrong: Je dois faire beau demain. (trying to say "it has to be nice tomorrow")
• Right: Il faut qu'il fasse beau demain. / Il doit faire beau demain.
• Why: For impersonal necessity, il faut is often more natural than devoir. However, at the A1 level, devoir is a perfectly valid starting point.

Practice Tips

1. Describe your daily obligations: Je dois me lever tôt. Je dois aller au travail. Je dois faire les courses. This connects the grammar to your real life.
2. Practice the three modal verbs together to feel their differences: Je veux partir (I want to leave), Je peux partir (I can leave), Je dois partir (I must leave).
3. Use devoir in its "owe" meaning at restaurants or with friends: Je te dois combien ? Tu me dois un café !

Related Concepts

• Regular -ER Verbs — devoir is followed by infinitives, often -er verbs