What is Kim Lâu?
Kim Lâu is one of three taboos Vietnamese families check before building a house, alongside Hoang Ốc and Tam Tai. It is also consulted when choosing a wedding year. Of the three it is the most avoided.
How it is calculated
Take your lunar age, meaning the year of the undertaking minus your birth year, plus one. Divide that by nine and read the remainder. Remainders of 1, 3, 6 or 8 count as affected; 0, 2, 4, 5 and 7 do not.
For example, someone born in 1990 is lunar age 37 in 2026. Thirty-seven divided by nine is four remainder one, so Kim Lâu applies.
The four kinds
Each remainder has its own name, taken from whoever folk belief holds is touched: remainder 1 is Kim Lâu Thân, the owner themselves; remainder 3 is Kim Lâu Thê, the wife; remainder 6 is Kim Lâu Tử, the children; remainder 8 is Kim Lâu Lục Súc, the household's livestock. The naming reflects the agrarian society in which the custom formed, where livestock was a meaningful share of a family's wealth.
Affected ages
From 12 to 75 the affected lunar ages are 12, 15, 17, 19, 21, 24, 26, 28, 30, 33, 35, 37, 39, 42, 44, 46, 48, 51, 53, 55, 57, 60, 62, 64, 66, 69, 71, 73 and 75. There is no need to memorise this: it is simply the output of one division, and any table that disagrees can be checked by dividing a few ages yourself.
How to read it
Kim Lâu is arithmetic on a single age number. It uses no heavenly stems, no five-element analysis and no birth chart, and everyone born in the same year gets the same answer. It is folk knowledge without scientific basis, best read as a shared convention rather than a private forecast.
In practice, when Kim Lâu applies but the other two taboos do not, many families proceed anyway, often borrowing an age for the rituals.