The standard way to say “good night” in French is “bonne nuit”, but there are multiple phrases to express the same thing. Here are a few that you can try.
Steps
Method 1 of 3: Part One: Standard "Good Night"

Step 1. Say “good night” with Bonne nuit! This literally means "good night" and is used when someone intends to leave a place for the night or go to sleep.
- Bonne means "good".
- Nuit means "night".
- Pronounce this phrase as bon NUÍ.

Step 2. Greet someone at night with Bonsoir! This also translates to "good night." Use it as a greeting when meeting someone at night, but not to say goodbye.
- The bon part means "good."
- The soir part means "night" / "late-night".
- Pronounce this greeting as bon-SUÁG.
Method 2 of 3: Part Two: Announce You're Going to Sleep

Step 1. Say:
Je you are going to sleep. This phrase translates as "I'm going to sleep" or "I'm going to sleep"
- Je means "I".
- Vais derives from the French verb "aller", which means "to go."
- Dormir is a French verb that means "to sleep."
- Pronounce the entire sentence as she ve dog-MIIG.

Step 2. The phrase Je vais me coucher can be translated as “I'm going to bed”
- Je means "I".
- Vais derives from the French verb “aller”, which means “to go”.
- Coucher is a verb that translates to "lie down." By adding the pronoun me in front, you will be saying "lie down".
- Pronounce the entire sentence as she ve me cushég.

Step 3. Use the jargon saying Je vais pieuter
This phrase is a French slang expression that also means "I'm going to sleep."
- Je means "I".
- Vais derives from the French verb “aller”, which translates to “go”.
- Pieuter is a French slang term that means "to sleep."
- The phrase is pronounced like she ve piuh-tehg.

Step 4. In an informal situation you can say Je vais roupiller
This phrase also belongs to French slang. Basically, it means "I'm going to take a nap."
- Je means "I"
- Vais derives from the French verb “aller”, which means “to go”.
- Roupiller means "take a nap."
- Pronounce the entire sentence as she ve gjupiyéh.
Method 3 of 3: Part Three: Other Ways to Say "Good Night"

Step 1. Say Dormez well
This phrase means "sleep well."
- Dormez derives from the French verb to sleep and means "to sleep."
- Good means "good."
- Pronounce the phrase like dogméh bian

Step 2. You want Fais de beaux rêves
Use this phrase if you want to wish someone "sweet dreams."
- Fais derives from the French verb faire and means "to do".
- De means "of"
- Beaux translates to "beautiful".
- Rêves means "dreams".
- The whole sentence is pronounced as fé de bó gje-veh.

Step 3. Say "J'espère que vous dormez tranquille"
This translates to "I hope you sleep well."
- J'espère means "I hope".
- What does it mean that".
- Vous means "you".
- Dormez derives from the French verb to sleep, which means "to sleep."
- Tranquille means "quiet".
- Pronounce the phrase as shespég que vúh dogmé tjanquil.

Step 4. Use "Dormez comme un loir"
Use this phrase to say "sleep like a dormouse."
- Dormez derives from the French verb to sleep, which means "to sleep."
- Comme means "like".
- A loir means "a dormouse".
- The phrase is pronounced as dogmeh comán luag.

Step 5. Say goodbye with a "Dormez comme un bébé"
Use this phrase to say "sleep like a baby."
- Dormez derives from the French verb to sleep, which means "to sleep."
- Comme means "scomo".
- A baby means "a baby."
- Pronounce this phrase as dogmeh eat baby.