The formal phrase to wish somebody “Happy Birthday” in Japanese is “O-tanjoubi omedetou gozaimasu”. In Kanji and Hiragana, it is written “お誕生日おめでとうございます”. For friends, you can use the more casual “Tanjoubi omedetou” (誕生日おめでとう) or “Happii Baasudee” (ハッピーバースデー) which is popular among younger people.

Tanjyoubi (誕生日) means birthday, while omedetou (おめでとう) stands for “congratulations.” “Gozaimasu” (ございます) is the polite form of the “to be” verb. When put together, these three elements make a polite birthday greeting.