Day 20: Obligation

devoir / il faut · 25 min

Yesterday was "want to" and "may". Today is "have to". There are two ways to say it, and il faut is far easier and far more common. Start there.

1. ★ il faut — no conjugation at all

il faut has exactly one form. It never changes for the subject, which makes it the best possible expression for a beginner.

★ il faut names no subject. It means "one must", which is exactly right for signs, rules and advice — and it means you never have to pick a pronoun, so the sentence comes out fast. Think of it as the French version of "you have to…" where "you" means anyone.⚠️ Il ne faut pas = "must not", not "don't have to". English blurs these ("you don't have to smoke" vs "you mustn't smoke"); French does not. For "don't have to", use ce n'est pas obligatoire or tu n'es pas obligé.

2. devoir — when the subject matters

il faut vs devoir — how to choose

Beginner strategy: speak with il faut, understand both.

⚠️ devoir also means "to owe" — Je vous dois combien ? = How much do I owe you?Same double meaning as English "I owe" / "I ought".

3. Need and obligation phrases

★ Il faut combien de temps ? is the standard way to ask how long something takes. You will use it constantly when travelling. ⚠️ Note avoir again — French has a need, exactly like it has hunger (Day 6). Je suis besoin is wrong.

4. Signs you'll actually see (reading only)

You only need to read these. But Poussez/Tirez you will meet at every door — and note the trap: Poussez looks nothing like "push" but means it, while Tirez looks like "tear" and means pull.

5. Dialogue — at a museum

You: Bonjour, il faut réserver pour visiter ?bohn-ZHOOR, eel foh ray-zair-VAY poor vee-zee-TAY? Do you have to book to visit?Staff: Oui, c'est obligatoire le week-end.wee, seh to-blee-ga-TWAR luh wee-KEND.You: D'accord. Il faut combien de temps pour la visite ?da-KOR. eel foh kohn-byan duh TAHN poor la vee-ZEET?Staff: Environ deux heures. Et il ne faut pas prendre de photos avec flash.ahn-vee-ROHN duh ZUR. ay eel nuh foh pa PRAHN-druh duh fo-TOH a-vek FLASH.About two hours. And no flash photography.You: Je peux prendre des photos sans flash ?zhuh puh PRAHN-druh day fo-TOH sahn FLASH?Staff: Oui, bien sûr. wee, byan SEWR.

★ environ (ahn-vee-ROHN) = about, approximately · sans (sahn) = without ↔ avec (a-VEK) = with. ⚠️ Don't confuse sans (without) with sang (blood) or cent (hundred) — all three sound the same. Context does all the work.

6. Exercises

A. Conjugate devoir.

1. Je ___ partir. 2. Vous ___ réserver. 3. Il ___ travailler. 4. Nous ___ payer.

B. Rewrite with il faut.

1. Je dois réserver. → 2. Vous devez changer à Châtelet. → 3. On doit acheter un ticket. →

C. Say it in French.

1. I have to leave now. 2. You mustn't smoke here. 3. I need help.
2. How long does it take? 5. Do you have to book?

D. ⚠️ Which is it? "You don't have to book" — is that Il ne faut pas réserver or something else?

7. Today's 10 sentences

1. Il faut réserver. — You have to book (eel foh ray-zair-VAY)
2. Il faut changer à Châtelet. — You change at Châtelet (eel foh shahn-ZHAY a shat-LEH)
3. Il ne faut pas fumer ici. — No smoking here (eel nuh foh pa few-MAY ee-SEE)
4. Il faut combien de temps ? — How long does it take? (eel foh kohn-byan duh TAHN)
5. Je dois partir maintenant. — I have to leave now (zhuh dwa par-TEER man-tuh-NAHN)
6. Je dois travailler demain. — I have to work tomorrow (zhuh dwa tra-va-YAY duh-MAN)
7. J'ai besoin d'aide. — I need help (zhay buh-ZWAN DED)
8. C'est obligatoire ? — Is it compulsory? (seh to-blee-ga-TWAR)
9. C'est interdit. — It's forbidden (seh tan-tair-DEE)
10. Environ deux heures. — About two hours (ahn-vee-ROHN duh ZUR)

8. 📲 Upload to LangNote

Tables 1 and 2 + the dialogue (5). Today the podcast mission earns its keep — il faut has one form, so hearing it on repeat sticks fast.

langNote is a paid subscription and this course recommends it. The 30 lessons are free and complete either way.