Lunar–Solar Converter
Convert dates between solar and lunar calendars.
Convert a solar date to lunar
Left blank, today's date is used. (1900–2100)
Lunar date
-
Enter a solar-calendar date.
Convert a lunar date to solar
The selected year/month/day is read as a lunar date.
Only check this if the year actually has a leap month at this number.
Solar date
-
Enter a lunar year, month and day.
What is the Lunar–Solar Converter?
This tool converts dates between the solar (Gregorian) calendar and the lunar (lunisolar) calendar. Useful for finding the solar date of a birthday, ancestral rite, or anniversary that follows the lunar calendar each year, and vice versa — including leap months.
How it is calculated
Using a standard conversion table covering 1900–2100 (month lengths of 29/30 days and leap-month positions for each lunar year), the tool compares accumulated day counts to find the matching lunar (or solar) date.
Supported range & caveats
| Calendar | Range |
|---|---|
| Solar | 1900-01-31 to about 2100 |
| Lunar | 1900-01-01 (lunar) to about 2100 |
Korea's official lunar calendar is defined by the new moon in KST, so results may differ by a day in rare cases when the new moon falls near midnight. Use for reference only.
Why the lunar and solar calendars drift
A lunar birthday lands on a different solar date each year because the two calendars measure different things — one the earth's orbit, the other the moon's phases.
The eleven-day gap and leap months
A lunation runs about 29.5 days, so twelve lunar months total roughly 354 — some eleven days short of a solar year, enough to pull the calendar away from the seasons within a few years.
An extra month is inserted every few years to correct this. In such a year there are thirteen months, and lunar dates fall nearly a month later on the solar calendar.
Dates in a leap month have no counterpart in ordinary years; custom generally moves the observance to the ordinary month of the same number.
Where the lunar calendar still applies
Seollal and Chuseok are set by the lunar calendar, so their solar dates move each year, as do Jeongwol Daeboreum and Buddha's Birthday. Many households keep ancestral rites on lunar dates.
Resident registration records a solar birth date, though some entries were filed as lunar — leaving the documented age and the observed birthday out of step.
Conversion tables are built from observation and computation, and dates far in the past or future can fall outside their range.
Legal basis
- Lunar calculation — Korea Astronomy and Space Science Institute almanac
- Lunar-based public holidays — Regulations on Public Holidays for Government Offices