In Japanese, the most common way to say 'happy birthday' is 'tanjoubi omedetou' or 'tanjoubi omedetou gozaimasu.' However, it’s also important to consider who you're speaking to in order to use the appropriate level of formality. Additionally, there are other birthday-related vocabulary that may come in handy. Below is some key information about birthday greetings in Japan.
Steps
Happy Birthday

Say 'tanjoubi omedetou' to friends. This is an informal way to say 'happy birthday' when speaking with someone you're familiar with.
- Only use this expression with people you are close to or can speak casually with. Generally, you can say it to friends, most classmates, children, and most of your siblings or cousins.
- Avoid using this form with anyone of higher status, such as teachers, supervisors, acquaintances, or older individuals. Etiquette is highly valued in Japanese culture, so using this casual phrase with someone of higher rank could be interpreted as rude.
- Tanjoubi means 'birthday.'
- Omedetou means 'congratulations.'
- Tanjoubi omedetou is written in kanji (Japanese characters, derived from Chinese) as 誕生日おめでとう.
- You should pronounce it as tan-giô-bi ô-mê-đề-tô.

Use the more formal 'tanjoubi omedetou gozaimasu.' This phrase is more formal and can be used as a polite and sincere way to wish someone a happy birthday.
- This is the phrase you should use with people of higher social standing, including older individuals, teachers, supervisors, and strangers.
- You can also use this phrase with peers or even with people you're close to in order to emphasize sincerity.
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- The full version of this phrase written in kanji is 誕生日おめでとうございます.
- You should pronounce it as tan-giô-bi ô-mê-đề-tô gô-gia-i-ma-sự.
Related Terms

Simply say 'omedetou' or 'omedetou gozaimasu.' While this isn’t a specific birthday expression, these two words are general congratulations and can be used to offer well wishes on someone's birthday.
- Omedetou means 'congratulations.' Use this simple phrase with people you’re familiar with or those of equal or lower social status, such as friends, classmates, or children.
- Omedetou written in pure Japanese is おめでとう. Pronounce it as ô-mê-đề-tô.
- Gozaimasu adds emphasis on formality or sincerity. Omedetou gozaimasu is appropriate for older individuals, teachers, supervisors, or anyone with a higher social rank.
- Omedetou gozaimasu written in pure Japanese is おめでとうございます. Pronounce it as ô-mê-đề-tô gô-gia-i-ma-sự.

Shout 'yatta!' This word is used to express excitement, similar to saying 'hooray!'.
- Yatta written in kana is やった.
- Yatta is pronounced as da-ta.

Use 'okurebasenagara' when sending a late wish. This word means 'late.'
- When wishing someone a belated happy birthday, you can say 'okurebasenagara tanjoubi omedetou.'
- The kanji and kana for okurebasenagara are 遅ればせながら.
- Pronounce okurebasenagara as ô-ku-rê-ba-sây-na-ga-la.

To ask someone's age, say 'Toshi wa ikutsu desu ka?' This roughly translates to 'How old are you?'
- Toshi (年) means 'year' or 'age.'
- Wa (は) is a particle used before nouns referring to people or things.
- Ikutsu (いくつ) means 'how many.'
- Desu ka (ですか) means 'is it?'
- The full sentence is pronounced as tô-si wa i-cút-su desu ka.

To ask someone's birthday, use 'Tanjoubi wa itsu desu ka?' This roughly translates to 'When is your birthday?'
- Tanjoubi (誕生日) means 'birthday,' wa (は) is a particle, and desu ka (ですか) means 'is it?'
- Itsu (何時) means 'when.'
- The full sentence is pronounced as tan-giô-bi wa ít-su desu ka.