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Chinese Zodiac Calculator (生肖)

Finds the Chinese zodiac animal (生肖 shengxiao), sexagenary year (干支 ganzhi), stem element, yin/yang, nayin (纳音) and fixed element for a birth date, using either the Chinese New Year boundary or the 立春 (Lichun) boundary, plus the traditional relationship groups (六合, 三合, 六冲, 六害, 相刑) and 本命年 years.

When to use

You need someone's Chinese zodiac sign and element from a Gregorian birth date, especially for January–February births where the boundary matters, or the sign's traditional compatibility groups.

Do not use when: You need a full Bazi chart with month, day and hour pillars (use bazi-four-pillars), or the Western star sign (use zodiac).

Formula

year_used = Gregorian year, minus 1 when birth_date is before Chinese New Year (or before 立春 with boundary = lichun); ganzhi index = (year_used − 4) mod 60; animal = branch = index mod 12; 六合 partner = (13 − b) mod 12; 三合 = b ± 4; 六冲 = b + 6; 六害 partner = (7 − b) mod 12

Popular usage starts the zodiac year at Chinese New Year; Chinese astrology (Bazi) starts it at 立春, so a person born between the two dates can have a different sign under each convention. Relationship groups follow the classical branch tables (六合子丑寅亥卯戌辰酉巳申午未; 三合申子辰亥卯未寅午戌巳酉丑; 六冲 opposite branches; 六害子未丑午寅巳卯辰申亥酉戌; 相刑寅巳申, 丑戌未, 子卯, 自刑辰午酉亥). Traditional calendar/cultural reference calculation; not a prediction, medical, legal or financial advice.

Inputs

Parameter	Type	Required	Description
`birth_date`	date	yes	Gregorian birth date (civil date in China Standard Time), 1900–2100.
`boundary`	enum: lunar_new_year \| lichun	default lunar_new_year	Which event starts the zodiac year: Chinese New Year (popular usage, default) or 立春 around 4 February (astrological usage).
`reference_year`	integer	no	Optional Gregorian year for which to report the age and whether it is a 本命年. Range: ≥ 1900, ≤ 2100

Outputs

Output	Type	Unit	Description
`zodiac`	string		Animal sign in English.
`zodiac_cn`	string		Animal sign character.
`year_ganzhi`	string		Sexagenary year, e.g. 庚午.
`year_ganzhi_pinyin`	string		Pinyin, e.g. Gengwu.
`year_english`	string		Stem element and animal, e.g. Metal Horse.
`stem_element`	string		Element of the heavenly stem with its character.
`yin_yang`	string		Polarity of the stem (and branch) of the year.
`nayin`	string		Nayin melodic element of the year ganzhi.
`animal_fixed_element`	string		Element of the earthly branch: Rat Water, Ox Earth, Tiger Wood, Rabbit Wood, Dragon Earth, Snake Fire, Horse Fire, Goat Earth, Monkey Metal, Rooster Metal, Dog Earth, Pig Water.
`year_used`	integer		Year number the birth date was assigned to under the chosen boundary.
`chinese_new_year_date`	date		Date of 正月初一 in the Gregorian year of birth.
`lichun_datetime`	string		Instant of 立春 in the Gregorian year of birth (China Standard Time).
`boundary_note`	string		Whether the birth date fell before or after the chosen boundary, and what the other convention would give.
`benmingnian_years`	string_list		Zodiac years of the same animal from the birth year to birth year + 96, with their ganzhi.
`secret_friend`	string		Six-harmony partner of the sign.
`trine_partners`	string		The two other signs of the same triangle of affinity.
`clash`	string		Opposite sign on the 12-branch circle.
`harm`	string		Six-harm counterpart of the sign.
`punishment`	string		Punishment partners: 寅巳申 and 丑戌未 groups, the 子卯 pair, or self-punishment (自刑) for 辰午酉亥.
`age_in_reference_year`	integer	years	Age reached on the birthday in reference_year (reference_year − Gregorian birth year); only when reference_year is given.
`is_benmingnian_in_reference_year`	boolean		true when the zodiac year numbered reference_year has the same animal as the birth year; only when reference_year is given.
`reference_year_zodiac`	string		Ganzhi and animal of the year numbered reference_year; only when reference_year is given.

Example

1990-02-10, New Year boundary (CNY 1990-01-27): {"birth_date":"1990-02-10","boundary":"lunar_new_year","reference_year":2026} → {"zodiac":"Horse","zodiac_cn":"马","year_ganzhi":"庚午","year_ganzhi_pinyin":"Gengwu","year_english":"Metal Horse","year_used":1990,"chinese_new_year_date":"1990-01-27","secret_friend":"Goat (羊)","clash":"Rat (鼠)","age_in_reference_year":36,"is_benmingnian_in_reference_year":true}

1990-02-03 with the 立春 boundary (立春 1990-02-04): {"birth_date":"1990-02-03","boundary":"lichun"} → {"zodiac":"Snake","year_ganzhi":"己巳","year_used":1989,"year_english":"Earth Snake","trine_partners":"Rooster (鸡) and Ox (牛)"}

GET https://tttkmbb.com/api/v1/calculate/chinese-zodiac?birth_date=1990-02-10&boundary=lunar_new_year&reference_year=2026

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/chinese-zodiac (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/chinese-zodiac · Markdown: https://tttkmbb.com/lunar/chinese-zodiac.md · JSON definition: https://tttkmbb.com/lunar/chinese-zodiac.json
MCP: server https://tttkmbb.com/mcp, tool find_chinese_zodiac
OpenAPI operationId: find_chinese_zodiac
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Chinese zodiac (Wikipedia) (reference)
Chinese calendar (Wikipedia) – calendar rules as standardised in GB/T 33661-2017 (reference)
Hong Kong Observatory – Gregorian-Lunar Calendar Conversion Table (government)

FAQ

Which boundary should I use?

For the popular zodiac sign (new-year greetings, birth-year animal) use Chinese New Year. For Bazi/Four Pillars charts and most feng shui schools use 立春 (about 4 February); only births between 立春 and Chinese New Year (or vice versa) are affected.

What is the 'fixed element' of an animal?

The element of the animal's earthly branch (e.g. Horse = 午 = Fire), which never changes; the stem element (Metal Horse, Fire Horse …) cycles with the year.

What is a 本命年?

A year with the same animal as your birth year (every 12 years, e.g. ages 12, 24, 36 …). Tradition treats it as a year to take care in; this is a cultural reference, not a forecast.

Related calculators

Sexagenary Cycle Calculator (干支) — Full 60-year cycle table and the years sharing a ganzhi.
Chinese Nominal Age Calculator (虚岁) — Nominal age (虚岁) and next 本命年 from the same birth date.
Zodiac Sign Calculator — Western star sign for the same birth date.