What is the birthday based on?

Birthday: According to the year, month, day, hour and four o'clock of birth, check the calendar to find out the location of heavenly stems and earthly branches where the four are located (heavenly stems: A, B, C, D, E, G, N, D, earthly branches: Zi Chou Yin Mao and Tatsumi, apply for lunch break), such as Jiazi Year, B, Ugly Month, C and Day. It's a calculated date of birth.