There are four ways to say “Happy Birthday” in Korean:
생일 축하해요: (saengil chukahaeyo) This is a polite version of the greeting.
생일 축하합니다: (saengil chukahamnida) This is a formal version of the greeting.
생신 축하드려요: (sengshin chuka deu-ryeo-yo) This is a very respectful version of the greeting.
You can also say “Happy Birthday” in Korean by saying:
“[Name], 생일 축하합니다” ([Name], saengil chukha hamnida)
“생일 축하하다” (sengil chuka-hada)
You can respond to birthday wishes in Korean by saying:
“오늘을 내 인생 최고의 생일로 만들어줘서 감사합니다” (oneureul nae insaeng choego-ui saengillo mandeureojwoseo gamsahamnida)