What is the difference between ‘oui’ and ‘si’ in French?

In French, both oui and si mean "yes," but the difference is that oui is used for an affirmative question, whereas si is used to say “yes” in reply to a negative question or to disagree with a negative statement.

Do you know how French people say “yes” in informal conversation? Would you like to learn other ways to say “yes”? In addition to covering oui and si, in this post we’ll also discuss other ways to say “yes” in informal, normal, and formal speech. Let’s dive in!

Use oui when you want to answer “yes” to an affirmative, closed question. Recall that affirmative questions are “regular” questions, without any negation in them. For example:

• Tu as reçu la facture d'électricité ?

  Translation: Have you received the electricity bill?
• Oui.

  Translation: Yes.

Answering a question with oui is usually enough in French, but just like you can sometimes answer a yes or no question in English with more than just “yes” (e.g. “yes, I did” or “yes, he can climb that wall”), in French you can also add a bit more to your answer.

• Est-ce qu’ils ont pris le train hier soir ?

  Translation: Did they take the train last night?
• Oui, ils l’ont pris hier soir.

  Translation: Yes, they did take it last night.

Here are some ways you can use oui that aren’t answering a question:

• In France, it is also not uncommon to hear people start a sentence with oui, even when they haven’t been asked a question. It’s a way to show their agreement with what has been said so far, similarly to “indeed,” “yes,” or even “yeah” in English.

  • Il y a de plus en plus de débats en France concernant la tenue vestimentaire des jeunes à l’école.

    Translation: There are more and more debates in France about the dress code of young people in school.
  • Oui, nous savons que, récemment, un établissement a interdit le port des claquettes-chaussettes en son sein.

    Translation: Yes / indeed, we know that, recently, a school has banned the wearing of sandals with socks (lit. sandals-socks) in its premises.

• In other instances, oui can be used as a French tag question when you want to show you are getting impatient!

  Les enfants, vous venez, oui ? Ça fait 15 minutes que je vous attends !

  Translation: Kids, are you coming or not? I’ve been waiting for you for 15 minutes!

  And, if the kids aren’t keen, they might reply:

  Peut-être que oui, peut-être que non.

  Translation: Maybe, maybe not.

Using oui is pretty straightforward. Let’s move on to the curious si.

Use si to mean “yes” in response to negative questions or to disagree with negative statements in French.

Here are some examples illustrating how you can use si to disagree with the assumptions of a negative question:

• Quoi ?! Vous n’avez jamais regardé cette série ?

  Translation: What?! You have never watched this series?
• Si !

  Translation: Yes, we have!

Si can also be used to express that you disagree with a negative statement:

Si doesn’t have to be used on its own. You can say also say any of these:

• Mais si !

  Translation: Yes!

  Literally: lit. (lit.) But yes!
• Ben si !

  Translation: Of course!

  Literally: lit. (lit.) Well yes!
• Bien sûr que si !

  Translation: Of course!

In France, it is not unusual to hear a conversation like this:

• A:

  Ce n’est pas Marion Cotillard ? 🤔

  Translation: Isn’t it Marion Cotillard?

• B:

  Non. 😑

  Translation: No, it isn’t.

• A:

  Si, c’est elle ! 🧐

  Translation: Yes, it is her!

• B:

  Non. 🙄

  Translation: No, it’s not.

• A:

  Si. 😕

  Translation: Yes, it is!

• B:

  Mais non ! 😠

  Translation: No!

• A:

  Mais si! 😤

  Translation: Yes!

And so on, until one person gives up! 😉

Now, what if you want to sound more like a native speaker and use colloquial French to say oui?
Carry on reading!

There are also other ways to say “yes” in French; some are formal, others are informal. You’ll want to say “yes” when you are having a chat with friends differently from how you’d say “yes” when answering the minister of economy!

Although the expressions I’m giving you below are widely used, it is interesting to note that the Académie française — the official authority that regulates the French language — recommends to simply use oui instead of the heavier expressions like tout à fait (meaning absolutely) or the more informal ones like carrément (meaning you bet). However, many people, like myself, believe that the Académie française is a bit conservative. Indeed, why stick to oui when the French language is so rich and always evolving? What do you think?

Let’s wrap up what we’ve covered in our post on oui and si:

• Oui is used to answer “yes” to an affirmative closed question.

• Si is used to reply “yes” to a negative closed question and to contradict a negative statement.

• Ouais (meaning yep) is the most common informal form of oui.

• Absolument or certainement are two other formal ways to say “yes.”

• Keep the expression mais oui for when you are frustrated!

Also, I hear some of you saying “What about non (meaning no)?" Well, here is a list of other ways of saying non in French !

Now, why not practice using oui and si in French with our exercises?