21 Ways to Say “I Don’t Know” and “I Don’t Understand” in French

You know how to say “yes” and “no” in French, but how about “I don’t know”? You may not always know the answer, and that’s okay. 

Here are all the ways to respond when you need to say “I don’t know” ( Je ne sais pas ) or “I don’t understand” ( Je ne comprends pas ) in French without losing face. 


How to Say “I Don’t Know” in French

1. Je ne sais pas — I don’t know

This is the most common and straightforward way to say “I don’t know” in French. It’s used in practically all scenarios, in much the same way was “I don’t know” is used in English. 

For example, if someone asks you a question and you don’t know the answer, you can simply say Je ne sais pas.

Note that in French negation, the word ne is often omitted when speaking out loud. In this case, you may simply say Je sais pas, especially in more casual situations.  

2. Je n’en ai aucune idée — I have no idea

This is a more emphatic way of expressing ignorance or lack of knowledge. It’s used when you want to convey a stronger sense of not having any clue about a particular matter.

You can use it in a similar context as Je ne sais pas, but with a heightened emphasis on the absence of any idea or knowledge. 

You can also shorten the expression to the quick and casual Aucune idée — No idea.

3. Je ne suis pas sûr — I’m not sure

Sometimes, the answer isn’t a clear “I don’t know,” but rather an uncertainty in the answer. In that case, use this expression. 

For example, if someone asks for your opinion and you’re not completely confident in your thoughts on the matter, you can respond with Je ne suis pas sûr to express your uncertainty.

4. Je ne saurais dire — I wouldn’t know

This phrase literally translates to “I couldn’t say” and it’s used when you feel unable to provide a definite answer due to lack of knowledge or uncertainty.

You might use this phrase when you want to express that you’re not in a position to provide a definite answer to a particular question.

Another variation on this phrase is Je ne pourrais pas te dire — I couldn’t tell you.

5. Chais pas — Dunno

Chais pas is a colloquial and informal way of saying Je ne sais pas. The contraction Chais is often used in casual spoken language. This informal variant is often used in everyday conversations, generally among people you’re familiar with.

6. Ça me dépasse — It’s beyond me

Use this phrase when something is so difficult for you to comprehend that you just can’t make sense of it. It could express bewilderment or frustration when faced with a puzzling situation. 

7. C’est un mystère pour moi — It’s a mystery to me

Similar to Ça me dépasse, use this expression when you’re completely baffled by something. 

8. Ça m’échappe — It escapes me

Is the answer to something so elusive that it’s escaped your mind? This is the expression for that situation. 

9. Je ne suis pas au courant — I’m not aware

More than just “I don’t know,” “Je ne suis pas au courant” is used to show a lack of awareness or familiarity with something. It implies that you might not have encountered or been informed about the particular topic, rather than a simple lack of knowledge.

How to Say “I Don’t Understand” in French

10. Je ne comprends pas — I don’t understand

This is the most common phrase to show that you’re unable to comprehend something. Whether something is confusing to you or you don’t know the vocabulary being used, use this expression to say so. This is an especially useful expression for new French language learners!

11. Je ne saisis pas / Je pige pas  — I don’t get it

This is a more formal and slightly literary way of conveying a lack of comprehension. It’s a polite way to communicate that you’re having difficulty understanding something.

12. Je pige que dalle — I don’t understand anything

Completely at a loss? This phrase empasizes that you just don’t get anything. It’s quite casual so save this one for friends and informal settings. 

13. Ça ne fait pas sens pour moi — It doesn’t make sense to me

When you just don’t get it, this expression is used to show your befuddlement and show that something doesn’t make sense to you. 

14. Ça me semble obscur — It seems unclear

Sometimes, the lack of understanding isn’t your own fault and has more to do with the situation or explanation. Use this phrase to express that something is difficult to understand because of its lack of clarity.

15. Je suis perdu — I am lost

If you’re wandering around the streets of Paris and your GPS is on the fritz, you can use “Je suis perdu”  to say that you are, quite literally, lost. But when it’s used figuratively, this phrase can mean “I’m confused” or “I don’t know what to do.” 

16. Je n’arrive pas à suivre — I can’t keep up

This expression is used when you’re having trouble following along with a conversation or explanation. It can also literally mean that someone’s speaking too quickly for you to understand. 

17. Ça me laisse perplexe — I am puzzled by it

Use this phrase to convey a sense of confusion about a particular situation, statement or information. 

18. C’est du chinois pour moi — It’s Chinese to me

This is a colloquial expression used to convey that something is completely incomprehensible or unintelligible. It’s similar to the English expression “It’s Greek to me” and means that something’s so difficult to understand that it might as well be in a different language. 

19. Je ne peux pas saisir le sens — I cannot grasp the meaning

Save this phrase for when the meaning of something is just out of your grasp, figuratively (or literally!).

20. Ça me laisse dans le brouillard — It leaves me in the fog

This phrase conveys an image of being lost in a fog, emphasizing the lack of clarity of something. You might use this phrase to express that something is unclear or ambiguous to you, leaving you with a sense of confusion or uncertainty.

21. Ça me dépasse totalement — It totally surpasses me

This expression is used to convey a strong sense of being unable to understand or cope with a situation. You might use it to express that something is entirely beyond your understanding.

How to Say “I Don’t Understand French”

Have something urgent to say or ask, and don’t want to spend any time stumbling through French? Use these expressions to let whoever you’re addressing know that you don’t understand French, or would prefer if they spoke English:

You might find these phrases useful when you first start out, but as you learn more French, you should try to communicate in the language. You’ll find that most people are very understanding and patient with people who are learning their language!

You can also bolster your confidence and French skills by studying the language with the FluentU program.

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More Phrases for Expressing Uncertainty in French

Still not sure about something and none of the above phrases quite fit the type of confusion that you’re afflicted with? Try these miscellaneous ways to express uncertainty:


There are still many things we don’t know, but at least now we know how to say “I don’t know” in French. And that’s an important skill to have! 

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