Chinese Zodiac & Lunar Age Calculator
Enter any Gregorian birth date and the calculator instantly returns the corresponding Chinese zodiac animal (rat / ox / tiger / rabbit / dragon / snake / horse / goat / monkey / rooster / dog / pig), the stem-branch year name (e.g. 1990 → 庚午, Yang Metal Horse), the five-elements affinity and yang-yin polarity. It also compares the traditional sui ("nominal") age commonly used in Hong Kong with the international western age, and tells you when your next benming (zodiac-recurrence) year arrives. Zodiac years pivot on Lunar New Year, so a 1990-01-15 birthday still belongs to the 1989 snake year rather than the 1990 horse year.
Please pick a valid date.
Your zodiac animal
Horse
庚午 · Yang Metal
- Stem-branch year
- 庚午
- Element
- Yang Metal
- Zodiac year
- 1990
- Nominal age (sui)
- 37 sui
- Western age
- 35 yr
- Next zodiac (benming) year
- 2026 This year is your zodiac year!
Zodiac years pivot on Lunar New Year — birthdays just before LNY roll over into the prior animal.
Formula
zodiacYear = Gregorian year (− 1 if born before that year's LNY) | stemIndex = (zodiacYear − 1984) mod 10 | branchIndex = (zodiacYear − 1984) mod 12 | sui age = currentZodiacYear − birthZodiacYear + 1
- · 1984 LNY (1984-02-02) anchors the most recent 60-year stem-branch cycle: 10 Heavenly Stems (Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui) × 12 Earthly Branches (Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai) = 60 unique year names that repeat indefinitely.
- · Branch → animal mapping is fixed: 子 Rat, 丑 Ox, 寅 Tiger, 卯 Rabbit, 辰 Dragon, 巳 Snake, 午 Horse, 未 Goat, 申 Monkey, 酉 Rooster, 戌 Dog, 亥 Pig.
- · Five-elements pairing: 甲乙 Wood, 丙丁 Fire, 戊己 Earth, 庚辛 Metal, 壬癸 Water. Odd-indexed stems (甲丙戊庚壬) are Yang; even-indexed (乙丁己辛癸) are Yin.
- · Sui age (虛歲): you start at 1 on the day you are born and tick over each Lunar New Year. Western age starts at 0 and ticks over on each Gregorian birthday — the two can differ by 1 or 2 years depending on when LNY falls.
- · Your benming year (本命年) is the next time the same zodiac animal comes around — once every 12 years. Folklore holds it as a luck-sensitive year traditionally marked by wearing red.
- · LNY dates come from the Hong Kong Observatory Gregorian–Lunar Calendar Conversion Table, covering 1900–2099. Dates outside this range return null.
- · Sources: Hong Kong Observatory (hko.gov.hk), USNO / NASA lunar ephemerides.
Frequently asked
I was born just before Lunar New Year — which zodiac am I really?
Zodiac years pivot on Lunar New Year, not Gregorian New Year. If your Gregorian birthday falls before that year's LNY, you belong to the previous zodiac year. A 1990-01-15 birthday looks like "horse" at first glance, but LNY 1990 was not until 1990-01-27 — so the date is actually still in the 1989 snake year. The calculator handles this pivot automatically; just enter the Gregorian date.
What's the difference between sui (nominal) age and western age?
Sui age (虛歲) counts you as 1 on your birthday and adds 1 each Lunar New Year — so a baby born in late lunar December can become 2 sui within weeks. Western age starts at 0 and adds 1 on each Gregorian birthday. Hong Kong elders, fortune-telling and traditional customs tend to use sui; medical records, schools and government forms use western age. The tool shows both side-by-side so you don't have to convert in your head.
What are stem-branch names like 甲子 or 丙午 — and what are they for?
Stem-branch names are the traditional way of labelling years, months, days and hours: 10 Heavenly Stems × 12 Earthly Branches in fixed order yield 60 unique combinations before the cycle repeats (one "sexagenary cycle"). For example 2024 is 甲辰 (Yang Wood Dragon) and 2026 is 丙午 (Yang Fire Horse). The system underpins Chinese astrology (BaZi / four pillars), date selection (擇日) and milestone birthdays like the 60th "huan-li" (還曆).
Some online zodiac calculators give me a different animal — which is right?
Most quick-and-dirty zodiac tools simply pivot on January 1 — that disagrees with the lunar calendar whenever your birthday falls in late January to mid February, which is the most common edge case. A separate tradition (used in BaZi / four-pillars astrology) pivots on Lichun (立春, around February 4). This calculator uses the most popular and folk-correct definition — Lunar New Year — with dates taken from the Hong Kong Observatory official conversion table covering 1900 to 2099.
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