Free online tool
Wedding date selection and couple compatibility
Compare two birth years on five separate measures, then find a year clear of Kim Lau and San Tai, and narrow it down to a month and a day.
Five measures, not one verdict
The tool deliberately scores five measures separately instead of announcing “compatible” or “not”, because in practice almost every couple has some favourable and some difficult points:
| Measure | What it looks at |
|---|---|
| Heavenly stems | Whether the year stems combine or clash |
| Earthly branches | Trine, six-harmony, or one of the four clashes |
| Na Yin elements | Whether the elements of the two years produce or control each other |
| Gua numbers | East group / West group in the Eight Mansions system |
| Folk method | A traditional cross-check used alongside the above |
Year, then month, then day
Working in this order saves a great deal of effort:
- Year — filtered by the couple’s ages: years falling under Kim Lau for the bride and San Tai years are removed.
- Month — pick a lunar month within a suitable year.
- Day — judged by the day officer, the lunar mansion, favourable and unfavourable stars, and the sign the day clashes with.
Searching for a beautiful day inside a year you should be avoiding is wasted work.
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Frequently asked questions
What is Kim Lau?
A calculation based on the woman’s nominal age, used to avoid certain years for a wedding or for building a house. By custom the bride’s Kim Lau is the one checked for a wedding year; it is most widely observed in northern Vietnam.
What is San Tai?
Three consecutive years within the twelve-year cycle, determined by the trine group of your zodiac sign. Custom advises against starting major undertakings during them.
Our signs clash. Does that mean we should not marry?
That is a decision for the two of you, not for a table. In classical practice no pair is wholly compatible or wholly incompatible — the five measures nearly always disagree with each other. The result is meant to show where care is needed.
Do these customs vary by region?
Yes, considerably, and between books as well. The tool uses the most widely applied method and shows the basis for each measure so you can compare it with your family’s tradition.