FlexiLingoIn one line
il fautis general necessity and has no subject;devoiris personal obligation and has one — and in the negative the two move far apart.
The forms on this page
| Form | Means | Sound |
|---|---|---|
devoir | must · have to — a personal obligation, with a subject | /də.vwaʁ/ |
il faut | one must — a general obligation, with no real subject | /il fo/ |
The table
| Structure | Meaning | Example |
|---|---|---|
il faut /il fo/ + infinitive | one must — general | Il faut partir. /il fo paʁ.tiʁ/ |
il faut que /il fo kə/ + subjunctive | somebody specific must | Il faut que je parte. /il fo kə ʒə paʁt/ |
devoir /də.vwaʁ/ + infinitive | I must — personal | Je dois partir. /ʒə dwa paʁ.tiʁ/ |
avoir besoin de /a.vwaʁ bə.zwɛ̃ də/ | to need | J'ai besoin de partir. /ʒe bə.zwɛ̃ də paʁ.tiʁ/ |
être obligé de /ɛtʁ ɔ.bli.ʒe də/ | to be obliged to | Je suis obligé de partir. /ʒə sɥi ɔ.bli.ʒe də paʁ.tiʁ/ |
il est nécessaire de /il ɛ ne.sɛ.sɛʁ də/ | it is necessary to — formal | Il est nécessaire de partir. /il ɛ ne.sɛ.sɛʁ də paʁ.tiʁ/ |
Conjugating devoir
| present | perfect | future | conditional | |
|---|---|---|---|---|
je /ʒə/ | dois /dwa/ | ai dû /e dy/ | devrai /də.vʁe/ | devrais /də.vʁɛ/ |
tu /ty/ | dois /dwa/ | as dû /as dy/ | devras /də.vʁa/ | devrais /də.vʁɛ/ |
il /il/ | doit /dwa/ | a dû /a dy/ | devra /də.vʁa/ | devrait /də.vʁɛ/ |
nous /nu/ | devons /də.vɔ̃/ | avons dû /a.vɔ̃ dy/ | devrons /də.vʁɔ̃/ | devrions /də.vʁi.ɔ̃/ |
vous /vu/ | devez /də.ve/ | avez dû /a.ve dy/ | devrez /də.vʁe/ | devriez /də.vʁi.e/ |
ils /il/ | doivent /dwav/ | ont dû /ɔ̃ dy/ | devront /də.vʁɔ̃/ | devraient /də.vʁɛ/ |
The
ûindûdistinguishes it fromdu, the partitive article. It disappears in the feminine and plural:due·dus·dues.
devoir — three meanings
| Meaning | Example | Pronunciation |
|---|---|---|
| obligation | Je dois partir. — I have to go | /ʒə dwa paʁ.tiʁ/ |
| strong probability | Il doit être malade. — he must be ill | /il dwa.t‿ɛtʁ ma.lad/ |
| owing money | Je te dois dix euros. — I owe you ten euros | /ʒə tə dwa di.z‿ø.ʁo/ |
English "must" has the same double life: "you must leave" (obligation) and "he must be ill" (deduction).
devoirsplits exactly the same way, so the second meaning needs no learning — only the third, "to owe", is new, and English shows a trace of it too in "due".
And the meaning shifts across the tenses:
| Meaning | Pronunciation | |
|---|---|---|
Je dois partir. | I have to go | /ʒə dwa paʁ.tiʁ/ |
J'ai dû partir. | I had to go — or — I must have gone | /ʒe dy paʁ.tiʁ/ |
Je devrais partir. | I ought to go (advice) | /ʒə də.vʁɛ paʁ.tiʁ/ |
J'aurais dû partir. | I should have gone (regret) | /ʒo.ʁɛ dy paʁ.tiʁ/ |
j'aurais dûis the regret construction and it is very common in speech:J'aurais dû t'écouter./ʒo.ʁɛ dy te.ku.te/ — I should have listened to you.
The negative — where the two constructions separate
| Structure | Meaning | Pronunciation |
|---|---|---|
Il ne faut pas partir. | you must not go — forbidden | /il nə fo pa paʁ.tiʁ/ |
Il n'est pas nécessaire de partir. | you don't have to go — optional | /il nɛ pa ne.sɛ.sɛʁ də paʁ.tiʁ/ |
Je ne dois pas partir. | I must not go — forbidden | /ʒə nə dwa pa paʁ.tiʁ/ |
Je n'ai pas besoin de partir. | I don't need to go | /ʒə ne pa bə.zwɛ̃ də paʁ.tiʁ/ |
il ne faut pasnever means "you don't have to". It always means "you must not". For "you don't have to", sayil n'est pas nécessaireoron n'est pas obligé.
English draws the same line and English speakers know it well: "you must not smoke" forbids, "you don't have to smoke" permits. Two negatives of the same idea, meaning opposite things. The trap is that French does not build them the same way: the negative of il faut gives you the forbidding one, not the permitting one. To permit, you have to change the verb, not just add ne … pas.
il faut — and what it takes
| What follows | Example | Pronunciation |
|---|---|---|
| an infinitive | Il faut manger. | /il fo mɑ̃.ʒe/ |
que + subjunctive | Il faut que tu manges. | /il fo kə ty mɑ̃ʒ/ |
| a noun | Il faut du courage. — it takes courage | /il fo dy ku.ʁaʒ/ |
And in the other tenses:
| Pronunciation | ||
|---|---|---|
| perfect | Il a fallu partir. | /il a fa.ly paʁ.tiʁ/ |
| imperfect | Il fallait partir. | /il fa.lɛ paʁ.tiʁ/ |
| future | Il faudra partir. | /il fo.dʁa paʁ.tiʁ/ |
| conditional | Il faudrait partir. — we ought to go | /il fo.dʁɛ paʁ.tiʁ/ |
il fautconjugates only withil— it has no other person. That is why it belongs withil-impersonnel.
pouvoir — the neighbour of devoir
| Meaning | Pronunciation | |
|---|---|---|
Je peux partir. | I can go — permission or ability | /ʒə pø paʁ.tiʁ/ |
Je ne peux pas partir. | I can't go | /ʒə nə pø pa paʁ.tiʁ/ |
Je pourrais partir. | I could go | /ʒə pu.ʁɛ paʁ.tiʁ/ |
Puis-je partir ? | May I go? — formal | /pɥiʒ paʁ.tiʁ/ |
In inversion with
je,peuxbecomespuis:Puis-je ?, notPeux-je ?English has the same formal/informal pair — "can I" versus "may I" — and
Puis-jesits where "may I" does.
Examples
| English | French | Pronunciation |
|---|---|---|
| I have to go. | Je dois partir. | /ʒə dwa paʁ.tiʁ/ |
| One must leave. | Il faut partir. | /il fo paʁ.tiʁ/ |
| You have to go. | Il faut que tu partes. | /il fo kə ty paʁt/ |
| You must not go. | Il ne faut pas partir. | /il nə fo pa paʁ.tiʁ/ |
| You don't have to go. | Tu n'as pas besoin de partir. | /ty na pa bə.zwɛ̃ də paʁ.tiʁ/ |
| I had to go. | J'ai dû partir. | /ʒe dy paʁ.tiʁ/ |
| I should have gone. | J'aurais dû partir. | /ʒo.ʁɛ dy paʁ.tiʁ/ |
| You ought to go. | Tu devrais partir. | /ty də.vʁɛ paʁ.tiʁ/ |
| He must be ill. | Il doit être malade. | /il dwa.t‿ɛtʁ ma.lad/ |
| May I go? | Puis-je partir ? | /pɥiʒ paʁ.tiʁ/ |
Common mistakes
| ❌ | ✅ | Why |
|---|---|---|
Il ne faut pas partir for "you don't have to" | Ce n'est pas nécessaire de partir | il ne faut pas means forbidden |
Il faut que je pars. | … que je parte. | il faut que requires the subjunctive |
Je dois de partir. | Je dois partir. | devoir takes a bare infinitive |
Nous fallons partir. | Il faut partir. | falloir exists only with il |
Peux-je ? | Puis-je ? | A special inverted form |
J'ai devu | J'ai dû | An irregular past participle |
Why il faut has no subject
a verb with nobody doing it
falloir comes from Latin fallere, "to be lacking, to be missing". In Old French il faut meant "it is lacking" — and from there it arrived at "it is necessary".
And necessity has no doer. "One must leave" — who says so? Nobody. It is a state of affairs, not an action.
So that il is not a real subject but a placeholder — the same il as in il pleut and il y a. The detail is in il-impersonnel.
English needs a dummy subject in exactly the same way — "it is necessary to leave" — so the construction itself is familiar. What English lacks is a single verb that does it, so the closest English gets is "one must", which sounds stiff, or "you have to", which smuggles a subject back in. il faut is neither stiff nor personal in French; it is the ordinary way to state a requirement.
And that is why both verbs exist:
| What it foregrounds | Pronunciation | |
|---|---|---|
Il faut partir. | the necessity itself — who does not matter | /il fo paʁ.tiʁ/ |
Je dois partir. | me — the person under the obligation | /ʒə dwa paʁ.tiʁ/ |
In formal writing il faut is more neutral and usually better. In personal speech devoir is more natural.