I don’t know in French: How to express lack of knowledge in French

Celine Segueg

Ironically, among the basic French phrases that you need to know is the phrase I don’t know. This statement, along with related statements like I don’t understand or I don’t know French, is essential in communicating a lack of knowledge, or that you need someone to repeat or rephrase what they’ve just said.

This is a beginner post, so we’re going to walk you through all the little details of these important phrases. We’ll start with the basic grammatical structure of I don’t know in French, and then go through those other forms that you might need. We’ll also explain a few other things that you may hear or see that are related to the phrase I don’t know in French. Where relevant, we’ll provide additional links to our other in-depth lessons within the text.

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I don’t know in French: The basics

First, let’s break down how to say I don’t know in French: the general French equivalent is je ne sais pas. Note that this is the basic equivalent; the French phrase may change a bit depending on the situation.

Generally speaking, you would say I don’t know in response to a question, particularly a question asking for information. There are a few different ways to ask questions in French, so it’s useful to be able to recognize them when you hear them! Some of the most common ways to ask questions in French are by using the question words, by starting with the phrase est-ce que, or by ending a statement with the tag question n’est-ce pas?.

The first word of the expression is je, which is the first-person singular subject pronoun meaning I. The second and fourth words are ne…pas, which are the basic negation words in French. Between ne and pas is the verb savoir, meaning to know. Savoir is conjugated in its first-person singular form, so je sais means I know. (It’s important to know that there are two different ways to say to know in French: savoir and connaître. These verbs are used in different contexts, so make sure you know which one fits your specific scenario!)

And there you have it, you now know the basics of how to say I don’t know in French: je ne sais pas. Now let’s move on to some of those other forms you may need.

I don’t know French

You may find yourself in a situation with a French speaker where you need to convey that you don’t know French that well. This will signal that your conversation partner needs to slow down or use simpler language.

There are a few different expressions that you could use in this situation, but the most straightforward is je ne parle pas français, which is a straight translation of I don’t speak French. You could also state I don’t know French by saying je ne connais pas le français, (using the other form of to know in French, connaître), but this phrasing isn’t as common.

If you want to qualify this statement to indicate that you are a beginner or that you know some French, you could add the modifier très bien after the word pas.

  • Je ne parle pas très bien le français. – I don’t speak French that well.
  • Je ne connais pas très bien le français. – I don’t know French that well.

Never fear, though! With time and practice, soon you won’t need these phrases at all!

I don’t understand

Sometimes you may need to use the expression I don’t understand in French, which is je ne comprends pas. Note that this phrase is similar grammatically to the phrase je ne sais pas; all you need to do here is replace the verb savoir, meaning to know, with comprendre, meaning to understand.

This expression could be used in a similar situation as described above, to indicate that you don’t understand the French that someone is speaking. However, saying je ne comprends pas implies that you know some French, but not a lot (yet).

You can also use je ne comprends pas in a more general sense that you don’t understand the meaning someone is trying to get across, even if you’re perfectly fluent in French. Luckily, the expression is the same no matter what the situation is!

Other abbreviations and variants

Now that you know these essential expressions, let’s talk about a few other things you may come across or want to incorporate into your own vocabulary.

First, when speaking informally, many French speakers will omit the ne in je ne sais pas, so you may hear je sais pas or even j’sais pas (which sometimes sounds like “shay pa” if they’re speaking quickly!). Though the phrase has been shortened, the meaning is still the same, like when English speakers shorten I don’t know to I dunno. Note that this is only in informal speech; in a formal setting or in writing, be sure to use the entire phrase je ne sais pas.

  • C’est quand la fête ? / J’sais pas. – When’s the party? / I dunno.

You may also see the phrase j’sais pas as a text abbreviation, like typing idk in French. Again, this is only for very informal contexts, so if you’re writing a letter or an email be sure to spell out the entire phrase.

If you want to add an extra layer of politeness, you can add a variant of sorry in French to convey that you regret not having the answer to someone’s question.

  • Pourriez-vous me dire qui est en charge du projet ? / Désolé, je ne sais pas. – Could you tell me who is in charge of the project? / Sorry, I don’t know.

Finally, you may have even heard a closely-related French expression used in English: je ne sais quoi. In English its literal translation is I don’t know what, but in French it conveys a sense of undefinable extraordinariness. Je ne sais quoi may share the first three words with je ne sais pas, but don’t get them confused!


So how do you say I don’t know in French? The next time you find yourself without the answer to someone’s question, you’ll know exactly what to say! Whether you’re talking to someone face-to-face, on the phone, or via text, you can confidently reply je ne sais pas.

And if you’re having a casual conversation, try shortening this expression to j’sais pas to sound more like a native speaker! Remember that context is important, so just stick with the grammatically correct phrase in more formal situations.

Keep practicing, and before long you won’t even need to say I don’t understand or I don’t know French anymore!