savoir (subjonctif)

Irregular Subjunctive of Savoir

Level 3

The verb savoir (to know) is irregular in the subjunctive. It uses the stem sach- followed by standard subjunctive endings. It is used in contexts of doubt, necessity, or emotion, and in common fixed expressions like que je sache.

How It Works

The subjunctive of savoir is essential for expressing knowledge in subjective contexts.

1. Conjugation Table:

  • que je sache
  • que tu saches
  • qu'il/elle/on sache
  • que nous sachions
  • que vous sachiez
  • qu'ils/elles sachent

2. Usage and Nuance:
While the indicative savoir asserts a fact (Je sais qu'il est là), the subjunctive is used when savoir is the subordinate verb triggered by expressions of doubt, necessity, or emotion (e.g., Il faut que tu le saches).

3. Fixed Expressions:
One of the most common uses in spoken French is the phrase 'que je sache' (as far as I know) or 'pas que je sache' (not that I know of). These act as 'hedges' to show that you aren't 100% certain.

4. Connection to the Imperative:
Interestingly, the imperative of savoir (Sache ! Sachons ! Sachez !) uses this same irregular stem. This is a rare trait shared only by a few other highly irregular verbs: être, avoir, and vouloir.

Examples (5)

  1. Il faut que tu saches la vérité.

    It is necessary that you know the truth.

    Word by Word: It must that you know the truth.

    The trigger 'il faut que' requires the subjunctive. Here, 'saches' is the second-person singular form.

  2. Il n'est pas encore arrivé, que je sache.

    He hasn't arrived yet, as far as I know.

    Word by Word: He is not yet arrived, that I know.

    This is a very common fixed expression used to qualify a statement with personal uncertainty.

  3. Je doute qu'ils sachent utiliser ce logiciel.

    I doubt that they know how to use this software.

    Word by Word: I doubt that they know to use this software.

    Verbs of doubt like 'douter que' trigger the subjunctive mood.

  4. Bien qu'elle sache nager, elle a peur de l'eau.

    Although she knows how to swim, she is afraid of the water.

    Word by Word: Although she knows to swim, she has fear of the water.

    The conjunction 'bien que' (although) always requires the subjunctive.

  5. Je veux que vous sachiez que je vous apprécie.

    I want you to know that I appreciate you.

    Word by Word: I want that you know that I you appreciate.

    The verb 'vouloir que' expresses a wish and triggers the subjunctive.

Common Mistakes

  • Using the indicative stem 'sav-' instead of 'sach-'.

    Il faut que je save.
    Il faut que je sache.

    Learners often try to follow the regular rule of using the 'nous' form (savons) to find the stem, but savoir is irregular and must use 'sach-'.

  • Using the subjunctive after 'Je sais que'.

    Je sais qu'il sache.
    Je sais qu'il sait.

    Even though 'que' is present, 'savoir' in the affirmative expresses certainty and therefore requires the indicative mood.

  • Confusing 'savoir' with 'connaître' in the subjunctive.

    Je doute qu'il sache Marie.
    Je doute qu'il connaisse Marie.

    Use 'savoir' for facts or skills, and 'connaître' for people or places. 'Connaître' has its own regular subjunctive stem (connaiss-).

How It Connects

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savoir (subjonctif)Level 3Irregular Subjunctive of Savoir

Learn This First

To learn the irregular subjunctive of 'savoir', you first need to understand how the subjunctive mood is formed and used in French. Additionally, you should be familiar with the verb 'savoir' in its basic present tense form.

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savoir