한국어

Korean Lunar Birthday Converter

Your lunar birthday is the second birthday many Korean families celebrate. Find out when it lands.

Convert a lunar date

See exactly where a Korean lunar date falls on the calendar you actually use.

What we need

Which way are we converting?

Takes a lunar date and gives you the date printed on your calendar.

Lunar date

Leave it on this year to see this year's date.

Lunar month
Lunar day

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Why a lunar birthday moves every year

A lunar year runs about eleven days short of a solar year. Left alone, Lunar New Year would drift into summer, so an extra month is slipped in every two or three years. That is why a lunar birthday lands on a different solar date each year, then snaps back.
CalendarLength of a yearWhat it follows
Solar365 days (366 in a leap year)One trip of the Earth around the sun
Korean lunarAbout 354 daysTwelve cycles of the moon filling and emptying
Lunar with a leap month354 days + one extra monthAn extra month added seven times every 19 years to catch up

More about the Korean lunar calendar 📚

Why a lunar birthday never lands on the same day

The Korean lunar calendar counts a month by the moon - from one new moon to the next, about 29 and a half days. Twelve of those add up to roughly 354 days, so a lunar year finishes about eleven days before the solar one does.

Your lunar birthday therefore slides earlier on the regular calendar every year, then jumps back the year a leap month is added. Same lunar date, different day on your phone.

The second birthday Korean families celebrate

Plenty of Koreans, especially anyone born before the 1990s, have their birthday recorded on the lunar calendar. So do jesa, the memorial days families hold for grandparents, which are still kept by the lunar date.

That means somebody has to look it up every single year. Put the lunar date in once and this converter gives you the next ten years of solar dates in one go.

Leap months, and the year yours disappears

A leap month repeats the month before it - a leap 5th month follows the regular 5th month - and the two are different days. If you were born in a leap month, most years will not have it at all. The custom is to celebrate on the same date in the regular month, and that is what this converter shows, labeled so you can see it was moved.
CalendarLength of a yearHow the gap is fixed
Solar365 daysA leap day every four years
Korean lunarAbout 354 daysA whole leap month, 7 times every 19 years

Where these dates come from

Lunar-to-solar conversion is not arithmetic. It follows published tables built from the real motion of the moon, which is also why Korean and Chinese lunar dates sometimes differ by a day.

This tool uses the official tables of the Korea Astronomy and Space Science Institute (KASI), covering the years 1000 through 2050.

Frequently asked questions ❓

A lunar year runs about 354 days - roughly eleven days shorter than a solar year. So the same lunar date keeps sliding earlier on the solar calendar, then jumps back whenever a leap month is added.
To stop the lunar calendar from drifting out of season, an extra month is inserted seven times every nineteen years. It repeats the month before it - a leap 5th month comes right after the regular 5th month - and the two are treated as different days.
Most years will not have your leap month at all, since leap months only come around every two or three years. The usual custom is to celebrate on the same date in the regular month. This converter does that for you and labels the row so you can see the date was moved.
Lunar months run either 29 or 30 days, so in some years your month ends on the 29th. The custom is to mark the day on the 29th, the last day of that month, and the converter switches to it automatically.
Seollal, the Lunar New Year, is the 1st day of the 1st lunar month. Chuseok is the 15th day of the 8th month, and Buddha's Birthday is the 8th day of the 4th month. That is exactly why their solar dates move every year.
From the year 1000 to 2050. Lunar to solar conversion is not a formula - it follows published tables built from the real motion of the moon, so it only covers the years those tables cover.
It is the traditional name for the year, built by pairing ten heavenly stems with twelve earthly branches. That makes sixty combinations before the cycle starts over, which is why turning 61 has its own name in Korea: hwangap, the year you complete a full cycle.

Sources 🌐