Chinese lunar calendar converter

How the calendars differ

The Gregorian calendar follows the solar year: 365 days, or 366 in a leap year. It is the calendar normally used on Taiwan’s birth certificates and identity records.

The Chinese calendar is lunisolar. Its months follow the Moon, starting on a new-moon day, and contain 29 or 30 days. Twelve months total about 354 days, roughly eleven days short of a solar year. About seven leap months in nineteen years keep it aligned with the seasons.

The twenty-four solar terms divide the Sun’s annual path into equal intervals. Start of Spring is around 4 February and Winter Solstice around 22 December; their lunar dates vary each year.

What is a leap month?

The twelve principal solar terms normally fall one per lunar month. Under the current rule, the month containing Winter Solstice is month 11. If there are thirteen months between two such months, the first without a principal term is the leap month. It repeats the preceding month’s number: leap month 6 follows regular month 6.

Nearby leap months: 2020: month 4; 2023: month 2; 2025: month 6; 2028: month 5; 2031: month 3; 2033: month 11; 2036: month 6. Select the option marked “Leap” for a birth in one of those months.

In 2033, the leap month is month 11, an unusual winter leap month. Some simplified calendars give month 7 instead; this page follows the Hong Kong Observatory’s published month 11.

Why a lunar birthday moves each year

A Gregorian birthday keeps its Gregorian date. A lunar birthday usually moves about eleven days earlier on that calendar each year, then about nineteen days later when the relevant leap month intervenes. Many families use lunar dates for birthdays and traditional celebrations.

Enter the original lunar birth date above to see the five-year list. The FAQ explains the conventions used for leap-month birthdays and day 30 in a short month.

BaZi months follow solar terms

The BaZi year changes at Start of Spring, and its months at section-term boundaries. A birth in lunar month 1 does not necessarily have the Yin (寅) month pillar. See the stems and branches guide for how the four pillars are derived.

The BaZi form accepts Gregorian dates and checks the precise solar-term boundary. It also adjusts time for longitude and the equation of time. Near a time-period boundary, this can change the hour pillar; see apparent solar time.

This date-only converter displays the year and month pillars after the term transition on a boundary date, with a separate note showing the pillars before it. A full chart needs the birth time to resolve that boundary and calculate an hour pillar.

When the zodiac year changes

BaZi uses Start of Spring; the common folk convention uses lunar month 1, day 1. They answer different calendar conventions. This tool shows both when they differ.

In 2026, Start of Spring is 4 February 2026 at 04:02 Taiwan time; Lunar New Year is 17 February 2026. Between the Start of Spring moment and Lunar New Year, BaZi uses 丙午, Horse, while the folk convention still uses 乙巳, Snake.

Supported range and source checks

The converter uses the same lunar data as the Zi Wei chart. The project’s recorded comparison against the Hong Kong Observatory’s daily tables for 1901–2100 found complete agreement from 1 January 1901 through 31 December 2096. A month-length difference in 2097 is why this converter stops at the end of 2096.

Solar-term times are calculated astronomically and rounded to the nearest minute. In a few years, a transition close to midnight may fall on a different date from a published observatory table. All calendar dates and displayed term times here use Taiwan time (UTC+8).

Frequently asked questions

How do I find a lunar birthday's Gregorian date each year?

Choose “To Gregorian” and enter the original lunar birth year, month and day, including the leap month when applicable. Do not replace the birth year with the current year. The result lists five yearly birthday dates starting with the current lunar year in Taipei, and marks dates that have passed. Converting a Gregorian birthday also provides the same list.

How are birthdays in leap months celebrated?

A leap month appears roughly every two or three years, and its month number varies. A common practice is to use the regular month of the same number when the matching leap month is absent. When that leap month does recur, some families use it and others still use the regular month. Customs vary; follow your family's practice. The actual birth-date conversion for a chart remains unchanged.

What happens to a birthday on lunar day 30 in a 29-day month?

Some families celebrate on day 29; others use day 1 of the following month. The five-year list here uses day 29 and states when it has made that adjustment.

Which zodiac year applies to a January or early-February birthday?

BaZi uses Start of Spring, usually around 4 February. The folk zodiac commonly uses Lunar New Year, which falls between 21 January and 20 February. Births between these boundaries can have different zodiac animals under the two conventions. The result shows both when they differ.

Can I create a BaZi chart with only a lunar birthday?

Yes. Convert the lunar birthday here, then enter the resulting Gregorian date, original birth time and birthplace in the BaZi form. You can also use its built-in lunar conversion. Be sure to choose the correct leap month. This page converts calendar dates only; apparent solar-time adjustment belongs to the full chart's time and location settings.

Which year should I enter for a lunar date?

Enter the year to which the lunar date belongs, written with four digits. Early in a Gregorian year, this may still be the previous lunar year: 19 January 2026 is lunar year 2025, month 12, day 1, so reverse conversion uses 2025. For Taiwan's ROC year numbering, add 1911; ROC year 114 is 2025.