Il faut: l'impersonnel d'obligation

Falloir is the verb that does the heavy lifting of must, have to, need to, and it's necessary in French — and it does so with remarkable efficiency: a single form, il faut, fits every person, every situation, every register. There is no je faux, no nous fallons, no past participle in agreement — falloir is defective, meaning it exists only in the third-person singular with a dummy il as subject. That il refers to nothing at all; it is grammatical scaffolding, the same empty il that appears in il pleut (it's raining) or il est trois heures (it's three o'clock).

This page covers what falloir is, the four ways it combines with the rest of the sentence (il faut + infinitive, + noun, + que + subjunctive, and il me faut), how each tense changes the meaning, and the constant trade-off with devoir — the only other everyday way to say "must" in French. By the end you should be able to drop il faut into any sentence where English would say "have to," "need to," or "it's necessary" — and recognize the subtle force differences between il faut, il faudrait, and je dois.

Falloir is defective: only il faut

Most French verbs have six person-forms in each tense — je parle, tu parles, il parle, nous parlons, vous parlez, ils parlent. Falloir has exactly one: the third-person singular, paired with the dummy il. The forms below are the entire conjugation of the verb. There are no others.

Three irregular stems run through the paradigm: fau- in the present (il faut), fall- in the imparfait, the participle, and the passé simple (fallait, fallu, fallut), and faud- in the future and conditional (faudra, faudrait). The subjunctive qu'il faille is its own outlier — a stem you will not see anywhere else.

There is no imperative (you cannot order an impersonal verb to do something), no participe présent (no fallant), and no compound forms beyond what is listed. Falloir gives you a tightly bounded toolkit — and that toolkit covers an enormous amount of the grammar of necessity.

The four constructions of il faut

Falloir combines with the rest of the sentence in four patterns. Each one expresses necessity, but the type of complement determines the type of statement. Knowing which pattern to use is half of mastering this verb.

1. Il faut + infinitive — generic necessity

When the necessity applies to no one in particular — to anyone, to people in general, to whoever finds themselves in a situation — French uses il faut + bare infinitive. There is no que, no de, no à — just il faut and the infinitive.

This is the impersonal form: it states a rule, a general necessity, a universal truth. English glosses it variously as "one must," "you have to" (with generic you), "it's necessary to," or "people need to" — French uses one construction for all of them.

2. Il faut + noun — what is needed

When the necessity is a thing rather than an action, il faut takes a direct noun complement. Translate it as "we need," "you need," "it takes" — the implicit subject is whoever the conversation is about.

The noun can be a partitive (du sucre, de la patience), a count noun (deux heures, trois œufs), or an abstract notion (du courage, de la chance). French is comfortable with the noun complement where English would often paraphrase with we need, you need, it takes.

3. Il faut que + subjunctive — specific subject

When the necessity falls on a specific person, il faut is followed by que and a clause whose verb is in the subjunctive. This is the canonical productive use of the French subjunctive — the construction that keeps the subjunctive alive in everyday speech.

The structure is rigid: il faut + que + subject pronoun + verb in subjunctive. There is no il faut tu viennes (the que is mandatory), and the verb after que must be subjunctive — never indicative. For -er verbs the subjunctive looks identical to the indicative in je / tu / il, which can mask the rule, but for irregular verbs the subjunctive is unmistakable: il faut que j'aille, never il faut que je vais.

For the deeper details of this construction — including tense matching across the il fallait que / il faudra que / il faudrait que sequence — see Il Faut Que + Subjunctive.

4. Il me faut — when the needer is a pronoun

When the person experiencing the necessity is named with a pronoun, French often uses an indirect-object pronoun before faut rather than a que-clause. The pattern is: dummy il + IO pronoun (me, te, lui, nous, vous, leur) + faut + thing or infinitive.

This is a more compact alternative to il faut que je..., and it appears constantly in everyday speech. For the full treatment of this pattern alongside plaire and manquer, see Il faut + indirect object.

How tense changes the meaning

Because il faut covers so much semantic ground, the tense alone often disambiguates the kind of necessity expressed. Watch how the meaning shifts as the tense moves.

Past: il a fallu vs il fallait

The split between il a fallu and il fallait tracks the standard passé composé / imparfait distinction. Il a fallu describes a single, completed instance of necessity that produced an action; il fallait describes an ongoing or backgrounded state, often with a hint that the necessity went unmet.

The il fallait + infinitive form is one of the most common French ways to express past regret or after-the-fact criticism: il fallait me prévenir — "you should have warned me."

Future: il faudra

Il faudra is the future of necessity — what will need to happen later. It is the standard way French handles "we'll have to," "you'll need to," "it will be necessary to."

Conditional: il faudrait — the polite "should"

Il faudrait is one of the most useful softened-necessity forms in French. It pulls the force of il faut down from "it's necessary" to "it would be a good idea / one should." Use il faudrait anywhere in English you would use should in a soft, advisory sense.

The il faudrait que + subjunctive variant is especially handy for offering advice without giving an order. Il faudrait que tu te reposes — "you should rest" — is what a friend says; il faut que tu te reposes — "you have to rest" — is what a doctor says.

Conditional past: il aurait fallu

For the deepest layer of past regret — what should have been done but wasn't — French uses il aurait fallu + infinitive or il aurait fallu que + past subjunctive.

This construction is parallel to j'aurais dû partir (should have left — see Devoir), with the difference that il aurait fallu is impersonal and tends to point to a generic past necessity rather than personal regret.

Falloir vs devoir: choosing the right "must"

French has two everyday verbs of obligation, and English speakers often hesitate. Here is the working distinction.

In conversational French, il faut que is more frequent and more emphatic than devoir. Devoir is more flexible — it can also mean be supposed to (scheduled future) or must be (inference) — but for plain obligation, il faut que tends to win in spoken French.

A brief note on s'il vous plaît / s'il te plaît

The most frequent fixed phrase in French built on a similar logic — s'il vous plaît / s'il te plaît (please) — is not built from falloir but from plaire ("to please"). Literally it means "if it pleases you." See Plaire construction. It is mentioned here only to head off the natural assumption that polite formulas would use falloir; they don't.

Common Mistakes

Mistake 1: Trying to conjugate falloir in another person.

This is the single most common beginner error with falloir. The verb has no personal forms — full stop. To express "I have to," you either keep the impersonal il faut and add que je, or you switch to devoir.

Mistake 2: Dropping que before a specific subject.

Mistake 3: Using the indicative after il faut que.

This trips learners constantly because aller is so high-frequency. Drill il faut que j'aille / tu ailles / il aille until it is automatic.

Mistake 4: Confusing il faut (necessity) with il faut + IO (need).

The pronoun goes before faut, like any IO pronoun: il me faut, il te faut, il lui faut, il nous faut, il vous faut, il leur faut.

Mistake 5: Translating English "should" with il faut instead of il faudrait.

In an invitation between friends, il faut que tu viennes sounds like an order. The conditional softens it to a suggestion, which is what the English should actually conveys.

Mistake 6: Using il a fallu where il fallait belongs.

Key takeaways

• Falloir is defective and impersonal — only il faut and its tense forms exist. There is no je faux.
• The four patterns: il faut + infinitif (generic), il faut + noun (need), il faut que + subjunctive (specific subject), and il me faut (need with IO pronoun).
• The conditional il faudrait is the polite "should" — softer than il faut, the natural form for advice and suggestions.
• The past il a fallu narrates one specific past necessity that produced an action; il fallait describes ongoing past necessity, often unmet.
• Il faut que is the most productive subjunctive trigger in spoken French. Il faut que j'y aille — "I have to go" — is the highest-frequency subjunctive sentence in the language.
• Il faut and devoir both express obligation, but il faut que tends to be more conversational and forceful; devoir is more flexible (also covers schedule and inference) and slightly more neutral.