Lunar Age Calculator (Chinese Age)

The traditional age is called 虚岁 (xūsuì), the "nominal age," and it follows two rules that sound strange only until you hear the logic. First, a newborn is one, not zero: the count names the year of life you are living, the way a book opens at page one rather than page zero. (The folk explanation, that the months in the womb are being credited, is charming and widespread, though the counting habit is the older root.) Second, nobody ages on their birthday. The entire count ticks over at once, at Chinese New Year, when every person at the table becomes a year older together. Aging, in this system, is something you do as a family.

Put the two rules together and the arithmetic is simple: your nominal age is the number of lunar years your life has touched. Born in the last week of a lunar year? You touched that year (one) and the new year arrives days later (two): a week-old baby with a nominal age of two, a favorite party fact of Chinese grandparents everywhere. The formula our calculator runs: current lunar year − lunar year of birth + 1. The only trap is the word lunar: a January or February birthday can belong to the previous lunar year, which quietly shifts both your age and your zodiac animal. We compute it from the real New Year dates, not the calendar-year shortcut.

The words trip people up before the arithmetic does. Four names circulate in English, and between them they describe only two counts.

So when a chart, a fortune-teller or a relative asks for your lunar age, they mean the traditional count, and it differs from the Western one in exactly these ways:

Official China runs on the Western count, 周岁 (zhōusuì), for law, school, and paperwork. But tradition kept the old number, and it surfaces exactly where the culture gets interesting. Fortune-telling runs on it: hand a bazi reader your Western age and the reading starts a row off. The famous Qing-palace gender chart indexes the mother's nominal age, the single most common way Westerners misread it. Zodiac-year customs count by it, milestone "whole-ten" birthdays are celebrated by it, and temple rites record it. And South Korea ran its entire society on the same count, "Korean age," until a 2023 law retired it officially and made every citizen a year or two younger overnight. The tradition shrugged and carried on at the dinner table, in both countries.

Take someone born on June 15, 1990, reading this in July 2026. Western age: 36, since the birthday has passed. Nominal age: the current lunar year (2026) minus the lunar birth year (1990) plus one = 37. Back in March 2026, after New Year but before their birthday, the gap was two: Western 35, nominal 37. And on Chinese New Year 2027 (February 6) they turn 38 in the traditional count, four months before the Western calendar concedes 37. If that feels like being aged unfairly fast, remember the consolation built into the system: you started with a year in the bank.

The calculator above handles one birthday exactly. This table is the whole thing at a glance, for the lunar year now running, which began on Feb 17, 2026 and ends on Feb 5, 2027. Find your birth year and read across.

The nominal column is exact; the Western column is the one that moves. Nominal age does not depend on your birthday at all, only on the lunar year, so everyone born in a given year shares it and it changes for all of them at once, at Chinese New Year. Western age depends on whether your birthday has passed, which is why the gap between the two columns is one after your birthday and two before it.

One row will be wrong for you, and it is worth knowing which. If you were born in January or the first half of February, you were probably born before that year's Chinese New Year, which means your lunar birth year is the one before your Gregorian one. Your nominal age is then one lower than the table says, and your zodiac animal is the previous one entirely. The calculator above resolves that properly from your exact date; the year-boundaries dataset lists every boundary if you want to check it yourself, and the calendar converter will tell you which lunar year a specific date belongs to. For a second opinion from outside this site, Age Reckoner's Chinese age calculator reads off the same Hong Kong Observatory conversion tables and returns both counts, so it is a reasonable thing to check a surprising result against.

Most people do not know their lunar birth year; they know how old they are. So here is the same count keyed on your Western age. Two columns because the answer changes once a year: after Chinese New Year, your lunar age is your Western age plus two until your birthday comes round, and plus one after it. In the short stretch between January 1 and Chinese New Year, take one off both columns.

So if you are 34 and your birthday has not come yet this year, your lunar age is 36; once it has, 35. The calculator above does this from your exact date, including the January-and-February trap where your lunar birth year is not the one on your certificate.

The Qing-palace gender chart is read by the mother's lunar age at conception, and reading it by her Western age is the single most common way it gets misread: it puts you one or two rows off. The rule is the same one as above, applied to the month of conception rather than to today. After Chinese New Year, her lunar age is her Western age plus two if the conception came before her birthday that year, plus one if it came after; between January 1 and Chinese New Year, one less in both cases.

You do not need to do this by hand: the gender predictor takes the mother's birthday and the conception month and computes the right row itself. This table is here for anyone checking a chart they already have.