Lunar Calendar Converter
Converts between lunar and solar dates, handling leap months, and lists a lunar birthday for years ahead.
A lunar birthday or a 제삿날 falls on a different solar date every year, and roughly every third year there is a leap month that has no equivalent at all. This converts in both directions and lists a recurring lunar date across the years ahead so it can go into a calendar.
Solar date
음력 — lunar
음력
2026, month 10, day 2
Weekday
Tuesday
간지 — sexagenary year
병오 (year of the horse)
Length of that month
30 days
큰달 — 30 days
The lunar calendar has no formula. It is a table, and the table is built from two observations: the instant of the new moon, and the instants at which the sun passes each 30° of longitude (the 중기). Everything after that is mechanical — the day containing the new moon is the first of the month, the month containing the winter solstice is month 11, and if thirteen months fall between two solstices, the first without a 중기 is the leap month.
This tool runs that computation in KST and builds the table for 1900–2100. The time zone matters: the Chinese calendar applies the same rules at UTC+8, so a new moon just before midnight in Korea puts the two a day apart. February 1988 was such a case — 설날 fell on the 18th in Korea and the 17th in China. A table copied from a Chinese source is wrong only in years like that.
How to use it
Enter a date in either calendar
Solar to lunar and lunar to solar are the same tool. A lunar date needs the leap-month flag when the month in question has one.
Generate the years ahead
For a birthday or a memorial, the list of future solar dates is the useful output — the single conversion is rarely what you came for.
Decide what to do about the 30th
A lunar month can have 29 or 30 days, so a date on the 30th does not exist in some years. Families differ on whether to observe it on the 29th or in the following month — the tool shows the gap rather than choosing for you.
Common questions
What is a leap month?
Twelve lunar months are eleven days short of a solar year, so about every third year an extra month is inserted to stop the calendar drifting through the seasons. It repeats the number of the month before it and is marked 윤 — 윤5월 follows 5월.
My lunar birthday has no date this year.
Either it falls on a 30th in a 29-day month, or it was in a leap month that does not recur. Both are shown as gaps in the list, so you can see it rather than get a silently shifted date.
Which time zone are the conversions in?
Korean Standard Time. A new lunar month begins at the instant of the new moon, and that instant can fall on either side of midnight — so the Korean and Chinese lunar calendars occasionally differ by a day.
Feed it from
24 Solar Terms
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Works out your 만나이, 연나이 and the old 세는나이 from a birth date, on any reference day.
Korean Public Holidays
Lists public holidays and substitute holidays for a year, including the lunar-dated ones, as a calendar or ICS.
Zodiac & Star Sign
Gives the Korean animal sign, the sexagenary year name and the star sign for a birth date.
Next
These accept what this tool produces, so the result can go straight in.
Add-to-Calendar & ICS
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Counts days, weeks, months and years between two dates, with a D-day view and business-day option.
Korean Public Holidays
Lists public holidays and substitute holidays for a year, including the lunar-dated ones, as a calendar or ICS.
Zodiac & Star Sign
Gives the Korean animal sign, the sexagenary year name and the star sign for a birth date.
Korean Age Calculator
Works out your 만나이, 연나이 and the old 세는나이 from a birth date, on any reference day.
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