Mentir Conjugation in French: The Complete Guide & Conjugation Charts

The French verb mentir translates directly to "to lie" (to deliberately tell an untruth). As an irregular verb of the 3rd group, mastering its patterns is essential for any French learner aiming for conversational fluency and grammatical accuracy.

In this comprehensive guide, you will learn how to conjugate mentir across all essential tenses, identify the underlying pattern it shares with other common verbs, and master its correct sentence structures.

1. Understanding the Verb Pattern of "Mentir"

Although classified as an irregular 3rd-group verb, mentir belongs to a very predictable family of verbs ending in -tir, -mir, and -vir (such as partir, sortir, sentir, and dormir).

The Golden Rule in the Present Tense:

  • In the singular forms (je, tu, il/elle/on), drop the final consonant of the root (t) and add -s, -s, -t:
  • Je men-s
  • Tu men-s
  • Il men-t
  • In the plural forms (nous, vous, ils/elles), restore the full stem (ment-) and add standard endings (-ons, -ez, -ent):
  • Nous ment-ons
  • Vous ment-ez
  • Ils ment-ent

The auxiliary verb used for compound tenses (like the passé composé) is always avoir, and the past participle is simply menti.

2. Complete Conjugation Charts for Mentir

Present Indicative (Présent)

  • Je mens – I lie / I am lying
  • Tu mens – You lie
  • Il / Elle / On ment – He / She / One lies
  • Nous mentons – We lie
  • Vous mentez – You lie (formal / plural)
  • Ils / Elles mentent – They lie

    • Used to describe habitual actions or current realities:

    Compound Past (Passé Composé)

  • J'ai menti – I lied / I have lied
  • Tu as menti – You lied
  • Il / Elle / On a menti – He / She / One lied
  • Nous avons menti – We lied
  • Vous avez menti – You lied
  • Ils / Elles ont menti – They lied

    • Used for completed actions in the past:

    Imperfect (Imparfait)

  • Je mentais – I used to lie / was lying
  • Tu mentais – You used to lie
  • Il / Elle mentait – He / She used to lie
  • Nous mentions – We used to lie
  • Vous mentiez – You used to lie
  • Ils / Elles mentaient – They used to lie

    • Used for past descriptions, ongoing states, or repeated past actions:

    Simple Future (Futur Simple)

  • Je mentirai – I will lie
  • Tu mentiras – You will lie
  • Il / Elle mentira – He / She will lie
  • Nous mentirons – We will lie
  • Vous mentirez – You will lie
  • Ils / Elles mentiront – They will lie

    • Used for actions that will take place later:

    Present Conditional (Conditionnel Présent)

  • Je mentirais – I would lie
  • Tu mentirais – You would lie
  • Il / Elle mentirait – He / She would lie
  • Nous mentirions – We would lie
  • Vous mentiriez – You would lie
  • Ils / Elles mentiraient – They would lie

    • Used for hypothetical situations or polite statements:

    Present Subjunctive (Subjonctif Présent)

  • Que je mente – That I lie
  • Que tu mentes – That you lie
  • Qu'il / elle mente – That he / she lie
  • Que nous mentions – That we lie
  • Que vous mentiez – That you lie
  • Qu'ils / elles mentent – That they lie

    • Used after expressions of doubt, necessity, or emotion:

    Imperative (Impératif)

  • Mens ! – Lie! (informal)
  • Mentons ! – Let's lie!
  • Mentez ! – Lie! (formal/plural)

    • Used for commands and advice:

    3. Important Grammar Rules & Prepositions

    Mentir à (Indirect Object)

  • Je ne veux pas lui mentir. (I don't want to lie to him/her.)
  • Tu m'as menti. (You lied to me.)

    • In French, you lie to someone (mentir à quelqu'un). Because of the preposition à, you must use indirect object pronouns (me, te, lui, nous, vous, leur):

    Mentir sur (To lie about)

  • Il a menti sur son CV. (He lied on his resume.)

    • When specifying the subject matter of the lie, use the preposition sur:

    4. Common French Idioms Featuring "Mentir"

  • Mentir comme un arracheur de dents (literally: "to lie like a tooth puller") – To lie shamelessly or compulsively.
  • Mentir comme on respire (literally: "to lie like one breathes") – To lie effortlessly and constantly.

By practicing the singular drop of the consonant -t and connecting mentir to its sister verbs like partir and sortir, you will be able to conjugate it seamlessly in both written and spoken French.