Falloir: Complete Paradigm Reference

This is the complete paradigm reference for falloir — a verb that exists only in the third-person singular with the impersonal subject il. There is no je faux, no nous fallons, no imperative, no normal infinitive use. The verb is defective: only certain forms are possible, and the subject can only be the dummy il. Despite the sparse paradigm, falloir is the single most productive trigger of the subjunctive in modern spoken French — il faut que tu fasses, il faut que vous partiez, il faut qu'on y aille. This page lays out every form that exists.

The companion page verb-reference/falloir covers everyday usage: how il faut combines with nouns, infinitives, and que + subjunctive; how il faut differs from devoir (semantic obligation vs. external necessity); and the impersonal logic that licenses the construction. This page is the paradigm reference.

Defective: what's there and what isn't

Before listing the paradigm, it helps to see what falloir doesn't have.

The reason for this defectiveness is semantic: falloir expresses an impersonal necessity ("it is necessary"). There is no notion of "I am necessary" or "we are necessary" parallel to je dois or nous devons — that meaning is carried by devoir. Because the verb has no first- or second-person semantics, French simply doesn't conjugate it for those persons.

The infinitive falloir is grammatically real (you need it after modals: il va falloir partir, il aurait fallu prévoir), but you will never see falloir with a subject other than il, and you will never see a person other than 3sg.

Etymology: Latin fallere

French falloir descends from Vulgar Latin fallere ("to lack, to be missing, to fail"). The original sense — "to be lacking" — explains the modern impersonal construction: il faut literally means something like "it is lacking" → "it is necessary that there be." The French sister verb faillir ("to fail, to nearly do") preserves the original "fail" meaning, while falloir specialized to the impersonal "be necessary." Both descend from the same Latin root and were formally distinguished only in the medieval period.

The 3sg present faut looks unrelated to the infinitive falloir, but both share the Latin fal- root: Latin 3sg fallit gave Old French falt, then the l vocalized to /w/ before the consonant t (regular Old French sound change, parallel to als → aus), yielding the medieval fault and modern faut.

Simple tenses: complete paradigms (3sg only)

Présent de l'indicatif

The single most productive subjunctive trigger in spoken French. Il faut is followed by:

• A noun: il faut du courage ("courage is needed")
• An infinitive: il faut partir ("we have to leave / one must leave")
• Que
  • subjunctive: il faut que tu partes ("you have to leave")

Imparfait

The imparfait carries two meanings: (1) ongoing past necessity ("it was necessary"), and (2) the politeness imparfait ("I had to / one needed to"). For ongoing necessity in the past, il fallait pairs naturally with the imparfait: il fallait qu'il arrive à six heures — "he had to arrive by six."

The form il fallait also appears in counterfactual reproaches: il fallait me prévenir ! — "you should have told me!" (literally "it was necessary to warn me"). This idiomatic use is extremely common.

Passé simple (literary)

The passé simple of falloir is reserved for literary narration. It expresses a punctual past necessity: "it became necessary, it was [at that moment] necessary."

Futur simple

The stem faudr- is irregular — note the d that doesn't appear in any other tense (compare with vendre → vendrai, where the d is part of the stem; here, it's an inserted consonant). The same pattern appears in valoir → vaudra and vouloir → voudra, all from the same Latin family.

Conditionnel présent

The conditional softens il faut — il faudrait is "it would be good if / one ought to / really should." It's a productive politeness device: instead of saying il faut que tu fasses ça (direct imperative-like force), you say il faudrait que tu fasses ça (gentler suggestion).

Subjonctif présent

Encountered after the rare contexts where falloir is itself in a subjunctive-triggering subordinate clause. The form qu'il faille /kil faj/ shows up after bien que, à moins que, pour que, avant que and similar conjunctions when they govern falloir.

Subjonctif imparfait (literary)

The 3sg of the subjunctive imparfait of falloir takes a circumflex: fallût. Without the circumflex, the form would be fallut, the passé simple. The two are pronounced identically /fa.ly/ but distinguished in writing by the circumflex. This form is one of the rarest in the language — encountered almost exclusively in 19th-century literature.

Impératif

Doesn't exist. No fais !, no fallons !, no fallez !. The impersonal verb has no command form because there's no addressee to command.

Participles and gérondif

The participle fallu is invariable — it never agrees with anything because falloir never has a direct object that could trigger agreement (only an infinitive complement or a que-clause). So il a fallu, il avait fallu, il aura fallu — fallu never changes.

Compound tenses: complete paradigms (3sg only)

Falloir uses avoir as auxiliary in compound tenses. As with all impersonal verbs, only the 3sg with il exists.

Passé composé

avoir (présent) + fallu

The most common compound form. Il a fallu expresses a punctual past necessity: "it was necessary, we had to" — pointing to a specific moment when the necessity arose.

Plus-que-parfait

avoir (imparfait) + fallu

Passé antérieur (literary)

avoir (passé simple) + fallu

Futur antérieur

avoir (futur) + fallu

This form is often used to express retrospective necessity: "it will have taken / it will turn out to have been necessary."

Conditionnel passé

avoir (conditionnel) + fallu

Il aurait fallu is one of the most useful conditional forms in French. It expresses retrospective regret or counterfactual necessity: "we should have, it would have been necessary." It's the polite-but-firm way to point out a past mistake.

Subjonctif passé

avoir (subjonctif) + fallu

Plus-que-parfait du subjonctif (literary)

avoir (subjonctif imparfait) + fallu

Il eût fallu is a famously elegant literary form, often used as a substitute for il aurait fallu in highly formal style: "it would have been necessary."

The infinitive falloir after modals

Although you cannot say falloir on its own (there's no je veux falloir), the infinitive does appear after the periphrastic modals aller, devoir, pouvoir, where it functions as the second verb in a chain. These constructions are common.

The construction il va falloir is one of the most common ways to introduce a forthcoming necessity in spoken French. It's a softer alternative to the bare il faudra.

Pronunciation notes

Three points are worth memorizing.

1. The 3sg present faut is /fo/ — a single syllable. The au spelling represents /o/ (closed o, like the eau in beau). The final t is silent.

2. The futur faudra and conditionnel faudrait insert a d. This is irregular — most futurs are formed on the infinitive, but falloir would have given fallorai or similar; instead, French extracted a faud- stem that aligns with vouloir → voudra and valoir → vaudra. All three verbs share this anomalous d.

3. The circumflex on fallût is obligatory in the subjunctive imparfait 3sg. Fallut (without circumflex) is the passé simple. The two are spelled differently to mark the mood distinction even though they sound the same /fa.ly/.

Comparison with English

Three friction points worth restating in a paradigm reference.

1. No personal forms. English uses "I have to, you have to, we have to" — the same lexical verb with personal subject. French uses il faut que je, il faut que tu, il faut que nous

   • subjunctive — the verb stays in 3sg with impersonal il, and the personal information shifts to the subordinate clause. Trying to say je faux is impossible French.

2. The il is a dummy subject, not a referential pronoun. Like English "it" in "it's raining" or "it's necessary," French il in il faut doesn't refer to anything. Beginners sometimes try to gloss it as "he must" — there is no "he."

3. The subjunctive after que is obligatory. Il faut que tu partes, never il faut que tu pars. Falloir is the most productive subjunctive trigger in modern spoken French — every learner needs to internalize this pattern.

Common Mistakes

Mistake 1: Trying to conjugate falloir with personal subjects.

Mistake 2: Using the indicative after il faut que.

Mistake 3: Spelling fallut (passé simple) instead of fallût (subjonctif imparfait) in formal writing.

Mistake 4: Forming the futur from the infinitive directly.

Mistake 5: Using falloir where devoir is expected.

The two constructions are roughly synonymous, but you choose one or the other — never both at once. Devoir foregrounds the personal obligation; il faut que foregrounds the external necessity.

Key takeaways

Falloir is defective: only the 3sg with impersonal il exists. There is no je faux, no nous fallons, no vous fallez, no imperative, no participe présent, no gérondif. The participe passé fallu is invariable.

The verb is the single most productive subjunctive trigger in spoken French — il faut que tu partes, il faut qu'on y aille, il faudrait qu'elle revienne. After il faut que, the subjunctive is obligatory. Never il faut que tu pars.

The compound tenses use avoir as auxiliary: il a fallu, il avait fallu, il aurait fallu, il aura fallu. The participle fallu never agrees.

The futur faudra and conditionnel faudrait show an irregular faud- stem with an inserted d, paralleling voudr- and vaudr-. The subjunctive present faille and the literary subjunctive imparfait fallût (with circumflex) round out the rare forms.

Six forms cover ~95% of usage: il faut, il fallait, il a fallu, il faudra, il faudrait, il aurait fallu. Memorize these cold; refer to this page when you encounter the rarer literary forms in reading.

This page is the paradigm reference. For the everyday usage — the noun, infinitive, and que-clause complements; the contrast with devoir; the politeness uses of il faudrait — see verb-reference/falloir.