Bon week-end !

Because week-end is a masculine singular noun in French.

• un week-end
• so: bon week-end

If the noun were feminine, you would use bonne instead.

French often leaves out the verb in short greetings and wishes.

So Bon week-end ! is a natural shortened form of:

• Je te souhaite un bon week-end.
• Je vous souhaite un bon week-end.

This is very similar to English expressions like Have a nice weekend!, where the full structure is also somewhat formulaic.

In these greeting-style expressions, French usually omits the article.

Compare:

• Bonne journée !
• Bonne soirée !
• Bon courage !
• Bon voyage !
• Bon week-end !

If you wrote the full sentence, the article would usually appear:

• Je te souhaite un bon week-end.

So the article is not wrong in general; it is just normally left out in this short exclamation.

It is a borrowed word from English, but it is fully established in French.

French speakers commonly use week-end in everyday speech. Even though it comes from English, it behaves like a normal French noun:

• it has a gender: masculine
• it combines with French adjectives: bon week-end
• it can take the plural: des week-ends

The traditional French spelling is week-end with a hyphen.

You may also sometimes see weekend, especially in less formal writing or depending on the dictionary/style guide, but week-end is a very safe standard choice for learners.

So if you are unsure, use:

• Bon week-end !

A simple pronunciation guide is:

• bon → roughly bohn but with a nasal vowel
• week-end → roughly wee-kend

A more French-like approximation is:

• bon = the n is not really pronounced as a full n sound
• week-end = both parts are pronounced, and the final consonants are usually heard

Important point: there is no liaison between bon and week-end, because week-end begins with a consonant sound (w).

So it sounds roughly like:

• bohn wee-kend

but with the French nasal sound in bon.

People usually say it at the end of the work or school week, especially when leaving on Friday.

Typical situations:

• to a coworker before going home on Friday
• to a friend when saying goodbye before the weekend
• in an email sent on Friday

It is a very common social expression, like saying Have a good weekend!

It works in both informal and fairly neutral/formal situations.

You can say it to:

• friends
• coworkers
• neighbors
• teachers
• clients, depending on context

If you want to make it a little warmer or more personal, you can add something:

• Bon week-end à toi ! for one person informally
• Bon week-end à vous ! for one person formally or to several people

But Bon week-end ! by itself is perfectly natural.

Yes, but this depends on the variety of French.

• In France, Bon week-end ! is very common.
• In Quebec and some other French-speaking areas, Bonne fin de semaine ! is often preferred.

So both can be correct, but Bon week-end ! is especially common in European French.

Yes, absolutely.

It is very common at the end of messages, for example:

• Merci encore, et bon week-end !
• Bien cordialement, bon week-end !

In a professional email, it sounds polite and natural, especially on Friday.

The plural is:

• des week-ends

And the adjective would also become plural:

• bons week-ends

However, in the expression Bon week-end !, you normally use the singular because you are talking about the upcoming weekend.

It is very common, but not strictly required.

• Bon week-end ! feels warm and natural.
• Bon week-end. is possible, but it can feel flatter in tone.

In greetings and wishes, French often uses the exclamation mark quite naturally.