How to Express Obligation and Necessity in French: "Il faut," "Devoir," and More

Mastering how to express obligation and necessity in French is essential for effective communication. Whether you need to talk about rules, responsibilities, or requirements, understanding when to use "il faut," "devoir," and other structures will significantly improve your fluency.

Many learners struggle with choosing the right phrase and conjugating verbs correctly. In this guide, we’ll simplify the different ways to express obligation and necessity in French, provide conjugation tables, and share practical tips to help you master these expressions.

Understanding Obligation and Necessity in French

French uses different expressions to indicate obligation or necessity, depending on the formality and specificity of the statement:

• "Il faut" – General necessity (impersonal expression)

• "Devoir" – Personal obligation (conjugated like a normal verb)

• Other expressions – Alternative ways to express obligation, such as être obligé de, avoir besoin de, and falloir que

Let’s explore each structure in detail.

Using "Il faut" for General Necessity

The phrase "Il faut" is an impersonal expression used to indicate a general necessity. It is always followed by an infinitive verb and does not change according to the subject.

Examples:

• Il faut manger pour survivre. (One must eat to survive.)

• Il faut étudier pour réussir. (You have to study to succeed.)

• Il faut être prudent en conduisant. (One must be careful when driving.)

This expression is common in rules and advice because it does not specify a subject.

"Devoir" and Its Conjugation for Personal Obligation

Unlike "il faut," "devoir" expresses personal obligation and is conjugated according to the subject. It translates to "must" or "have to."

Present Tense Conjugation of "Devoir"

SubjectDevoir (to have to)JedoisTudoisIl/Elle/OndoitNousdevonsVousdevezIls/Ellesdoivent

Examples:

• Je dois finir mon travail. (I must finish my work.)

• Tu dois respecter les règles. (You must follow the rules.)

• Nous devons partir à l’heure. (We must leave on time.)

Other Ways to Express Obligation and Necessity

French offers alternative ways to express obligation, depending on tone, formality, or necessity level.

1. "Être obligé de" (To be obliged to)

Used when an obligation is imposed on someone.

• Je suis obligé de partir tôt. (I am obliged to leave early.)

• Ils sont obligés de porter un uniforme. (They are required to wear a uniform.)

2. "Avoir besoin de" (To need to)

Indicates necessity or requirement.

• J’ai besoin de dormir. (I need to sleep.)

• Tu as besoin de réviser avant l’examen. (You need to review before the exam.)

3. "Falloir que" + Subjunctive

This phrase is often used in formal writing and requires the subjunctive mood.

• Il faut que tu viennes tôt. (You must come early.)

• Il faut que nous étudiions davantage. (We need to study more.)

French Obligation Expressions in Different Tenses

Past Tense (Passé Composé)

Subject Devoir (Past Tense) J’ai dû/Tu as dû/Elle/On a dû/ Nous avons dû/Vous avez dû/ Ils/Elles ont dû

• J’ai dû partir tôt. (I had to leave early.)

• Nous avons dû attendre longtemps. (We had to wait a long time.)

Future Tense (Futur Simple)

Subject Devoir (Future Tense) Je devrai/Tu devrasIl/Elle/On devra/Nous devrons/ Vous devrez/ Ils/Elles devront

• Je devrai étudier ce week-end. (I will have to study this weekend.)

• Ils devront faire attention. (They will have to be careful.)

Common Mistakes to Avoid

1. Mixing up "il faut" and "devoir"

   • Il faut que je pars ❌ → Il faut que je parte ✅ (subjunctive required!)

2. Using "devoir" incorrectly in the past

   • J’ai dû aller au supermarché hier. (Correct)

   • Je devais aller au supermarché hier. (Indicates an intention, not an obligation.)

3. Forgetting the infinitive after "il faut"

   • Il faut étudier. (Correct)

   • Il faut que étudie. ❌ (Incorrect)

Practical Tips for Mastering Obligation Expressions

• Practice Conjugation Daily: Especially for "devoir."

• Memorize Set Phrases: Like il faut + infinitive and falloir que + subjunctive.

• Use Flashcards: To reinforce different obligation structures.

• Listen to Native Speakers: Pay attention to how obligation is expressed in real conversations.

How Our French Classes Can Help

At Polyglottist Language Academy, our courses provide:

• Grammar-focused lessons tailored to your level.

• Interactive exercises to practice obligation expressions.

• Personalized feedback to correct mistakes and improve fluency.

If you want to confidently express necessity in French, our structured lessons will help you master these essential grammar rules.

Conclusion & Call to Action

Understanding obligation and necessity in French is crucial for clear communication. Whether you use "il faut," "devoir," or alternative expressions, mastering these structures will help you speak more naturally.

Ready to improve your French?

Join our French classes at Polyglottist Language Academy today!