Zi Wei Birth Conventions: Leap Month, Rat Hour and Age
A Zi Wei result depends on the lunar birth month, two-hour birth period, day-change rule and age count. Compare these coordinates first when two charts use the same birth record.
Leap-month split
The calculator lets you keep the repeated lunar month number or split the month after day fifteen. The split treats the second half as the next month for palace setup. A leap-month birth is where this choice changes the month coordinate.
Early and late Rat hour
00:00–00:59 is early Rat, while 23:00–23:59 is late Rat. The chart’s late-Rat setting moves the lunar day forward at 23:00; a current-day school retains the civil date until midnight. The branch remains Rat in both cases.
Age and chart layers
Nominal age begins at one and advances at Lunar New Year; birthday age counts completed birthdays. This chart uses nominal age for decade and annual layers. The Chinese age calculator displays both counts for one target date.
Transformation-table comparison
Read the four stars in Lu, Quan, Ke, Ji order for the reference stem. Choose the current register or Ye Hanliang’s 2025 Doushuroll table in the calculator and star reference. The latter assigns Sun as Wu-stem Ke, and Tian Fu as both Geng-stem and Ren-stem Ke. The other Lu, Quan, Ke and Ji assignments agree. The selected register applies to the natal, decade and annual transformation layers; palace placement stays the same.