Born in January — which Chinese year counts?
Published 2026-08-20
If you were born in January, your Kua number is worked out from the year before the one on your birth certificate. That holds for every January birthday from 1900 to 2100 with no exceptions, because Eight Mansions (八宅, Ba Zhai) counts the year from the beginning of spring (立春, lichun), and that moment always falls in February — on the 3rd, 4th or 5th, depending on the year.
Your zodiac animal is a different question with a different answer. The animal turns at Chinese New Year, which can fall in January or February, so a January birthday sometimes gets the new animal and sometimes the old one. Both boundaries are correct.
The Kua side: January is always the year before
effectiveYear in src/lib/kua.ts compares your birth date with the start of spring for that year. A
January date is always earlier, so it returns the previous year. Nothing about your birth time matters
either — the hour only decides for someone born on the boundary day itself, which is never in January.
So a man born on 15 January 1990 is calculated from 1989, which gives Kua 2 and the West group. A woman born the same day is also calculated from 1989, which gives Kua 4 and the East group.
The zodiac side: it depends where Chinese New Year fell
Chinese New Year 1990 fell on 27 January 1990. So two babies born eleven days apart that January get different animals, while both are calculated from 1989 for Kua purposes:
| Born | Animal year | Kua year |
|---|---|---|
| 15 January 1990 | 1989, Earth Snake | 1989 |
| 28 January 1990 | 1990, Metal Horse | 1989 |
| 28 January 2025 | 2024, Wood Dragon | 2024 |
| 30 January 2025 | 2025, Wood Snake | 2024 |
| 15 January 2026 | 2025, Wood Snake | 2025 |
Rows two and four are the split cases: the animal has already turned, the Kua year has not. Row five is the ordinary case, where Chinese New Year came in the middle of February and both answers point at the previous year.
Chinese New Year lands in January in 71 of the 201 years from 1900 to 2100, and in February in the other 130. Its earliest date in that range is 21 January 1966 and its latest is 20 February 1920. Counting every January day in the range that falls on or after Chinese New Year gives 410 days — those are the birthdays where the two answers disagree. The widest single window is 1966, with eleven such days.
The mistake this sets up
Someone born on 28 January 1990 is usually told, correctly, that they were born in the year of the Metal Horse — the 1990 animal. It is then very natural to type 1990 into a Kua calculator. Doing that changes the answer completely:
| Born 28 January 1990 | Counted from 1989 | Counted from 1990 |
|---|---|---|
| Man | Kua 2, West group | Kua 1, East group |
| Woman | Kua 4, East group | Kua 8, West group |
Both rows cross the group line, and the two groups share no favorable direction at all. This is not a small error at the edges; it is the largest error the calculation can make.
The Kua number calculator applies the February boundary itself, and when it shifts your year it says so in the line under the result, so you can see which year it used rather than having to trust it.
Why there are two boundaries at all
The zodiac animal belongs to the lunar calendar. Chinese New Year is the first day of the first lunar month, and its date moves with the moon, which is why it wanders between late January and late February.
The Kua year belongs to the solar calendar of twenty-four terms. The beginning of spring is the moment the sun reaches a fixed point, and the same boundary governs the annual positions such as the Tai Sui. Neither calendar is a rounding of the other, and neither school borrows the other’s date. When does the Chinese year actually start sets the two side by side for several years running.
The practical version: use Chinese New Year for the animal and the stem-branch name of the year, and use the beginning of spring for anything about directions.
If your birthday is in the first days of February
February is where care is needed. The start of spring is a moment, not a date, so on the boundary day the hour decides. In 2025 spring began at 22:10 UTC+8 on 3 February 2025, so a birth at 21:00 that day is counted from 2024 and a birth at 23:30 is counted from 2025 — two different Kua numbers, in opposite groups.
Any calculator that assumes 4 February is wrong in 73 of the 201 years the site covers, since the date is 3 February in 39 of them and 5 February in 34. If you were born on 3, 4 or 5 February and do not know your birth time, you have two candidate numbers rather than one, and the honest handling is to run both.
Two boundaries, both correct, different questions
Knowing which year to count from tells you which of the two tables applies to you. It does not tell you that the directions in that table do anything measurable; Eight Mansions names directions, and this site reports what it names and stops there. See method and assumptions for the boundaries we compute from and the range they hold over. One limit worth stating: these dates are computed for UTC+8, so a birth in another time zone within a few hours of the boundary needs converting first, and the calculator does not do that for you.