House-building age check
Enter the owner's lunar birth year to see whether any of the next 10 years falls in Kim Lâu, Hoang Ốc or Tam Tai. Tradition checks the male head of the household for building; if the owner is a woman or there is no male head, books differ and you may enter the birth year of the person named on the deed. Everything runs in your browser; nothing is sent anywhere.
How each taboo is computed
- Kim Lâu: take the nominal age (target year − lunar birth year + 1) mod 9. Remainder 1 is Kim Lâu Thân, 3 Thê, 6 Tử, 8 Lục súc; remainders 0, 2, 4, 5, 7 are clear. Some sources use the last digit of the age instead, which gives different results.
- Hoang Ốc: add the digits of the nominal age and take the remainder by 6 (0 counts as 6): 1 Nhất Cát, 2 Nhị Nghi, 3 Tam Địa Sát, 4 Tứ Tấn Tài, 5 Ngũ Thọ Tử, 6 Lục Hoang Ốc. Nhất Cát, Nhị Nghi and Tứ Tấn Tài are favourable; the other three are not.
- Tam Tai: three consecutive years by the birth year's triple-harmony group. Thân, Tý, Thìn meet Tam Tai in Dần, Mão, Thìn years; Hợi, Mão, Mùi in Tỵ, Ngọ, Mùi; Dần, Ngọ, Tuất in Thân, Dậu, Tuất; Tỵ, Dậu, Sửu in Hợi, Tý, Sửu.