Your lunar birthday is the second birthday many Korean families celebrate. Find out when it lands.
See exactly where a Korean lunar date falls on the calendar you actually use.
| Calendar | Length of a year | What it follows |
|---|---|---|
| Solar | 365 days (366 in a leap year) | One trip of the Earth around the sun |
| Korean lunar | About 354 days | Twelve cycles of the moon filling and emptying |
| Lunar with a leap month | 354 days + one extra month | An extra month added seven times every 19 years to catch up |
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.
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.
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.
| Calendar | Length of a year | How the gap is fixed |
|---|---|---|
| Solar | 365 days | A leap day every four years |
| Korean lunar | About 354 days | A whole leap month, 7 times every 19 years |
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.
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.
