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A Gregorian date and its Chinese lunar equivalent describe the same calendar day. Conversion changes the label, not the event. For a family birthday, first establish which calendar the original record uses, then decide whether you want the birth date or a birthday occurrence in another year.
Two calendars, different month boundaries
The Gregorian calendar has months of 28, 29, 30 or 31 days. The Chinese calendar used here is lunisolar: its months follow a lunar cycle while leap months help keep the calendar aligned with the seasons. A Chinese lunar month has 29 or 30 days. A leap month is an additional month, not an extra day added to February.
Why a lunar birthday moves on the Gregorian calendar
Keeping a Chinese lunar month and day fixed does not keep the Gregorian month and day fixed. Do not take the Gregorian equivalent from the birth year and simply replace the year. For example, Chinese New Year begins on 17 February in 2026, while 16 February still belongs to the preceding Chinese lunar year. The Gregorian year number alone does not identify the lunar year.
What to enter
For Gregorian-to-lunar conversion, enter the complete Gregorian birth date. For the reverse direction, provide the numeric Chinese lunar year, month, day and leap-month flag. A repeating zodiac or stem-and-branch name cannot identify one unique birth year. Ordinary month six and leap month six must remain separate inputs even when their day numbers match.
Check the result in both directions
Use the date converter, record the complete result, and convert that result back. It should return the original Gregorian date. This can reveal a missing leap-month flag or a transcription error. It cannot establish that an uncertain family recollection was correct in the first place; retain the original wording alongside the verified date.
Keep conversion separate from celebration
A year may lack the required leap month or day 30. An unavailable exact match is not permission to silently replace the birthday with another date. A family can choose an ordinary month, a Gregorian birthday or a convenient weekend for celebration, but keep that decision in a separate field.
Scope and the next useful step
The verified Chinese lunar conversion range is 1 January 1950 to 31 December 2035. The tool accepts calendar dates rather than birth times and does not convert an instant between time zones. When working with a timestamp, first establish the relevant local date. To find occurrences within a selected Gregorian year, continue to the lunar birthday finder, which preserves the original month, day and leap-month condition.