Korean Lunar Birthday Calculator
See what solar date a lunar birthday falls on each year, then take the whole list into your calendar.
| Lunar year | Solar date | Birthday | Note |
|---|
The date you enter and the file you download stay in this browser.
How to use
- Pick the lunar date of birth. Tick 윤달 if the birth was in a leap month.
- Choose how many years to list, what to call the entry, and whether you want a reminder.
- Read the solar dates, then copy the list or download the .ics file and open it in your calendar app.
Examples
How far the date moves
A birthday on lunar 8/15 falls on 25 September 2026 (Friday), 15 September 2027 (Wednesday) and 3 October 2028 (Tuesday). That is a three-week spread across three years: twelve lunar months run about eleven days short of a solar year, so the date creeps earlier until a leap month pushes it back again.
A birthday on the 30th
Lunar months are 29 or 30 days, and which is which changes from year to year. A birthday on lunar 8/30 falls on 10 October 2026, but the 8th month of 2027 has only 29 days, so it is kept on the 29th and lands on 29 September. Between 2020 and 2040 only eight years have a 30-day 8th month, so this is the normal case rather than an edge case.
A birthday in a leap month
Someone born in the leap 6th month of 2025 does not see that month again until 2036; the one before was 1987, thirty-eight years earlier. In every other year the regular 6th month is used and the row is marked. Leap 4th months are rarer still — after 2020 there is not another one before 2050.
Setting a date for a 60th
Hwangap (환갑) is the sixtieth lunar birthday, when the sexagenary cycle returns to the year of birth. For someone born on lunar 3/10 in 1966 it falls on Sunday 26 April 2026. The list marks that row, and the weekday is right there, which is usually what decides the date of the party.
Getting it into a calendar
The download is a standard .ics file. Google Calendar takes it under Settings → Import, iPhone and Mac open it straight into Calendar, and Outlook imports it under File → Open & Export. A reminder, if you choose one, fires at 09:00 the chosen number of days before rather than at midnight.
FAQ
Why does the solar date change every year?
Twelve lunar months come to about 354 days, some eleven days short of a solar year, so a lunar birthday moves earlier on the solar calendar each year. Before it drifts out of season a thirteenth month is inserted, which pushes it back by nearly a month. That saw-tooth is why a lunar birthday cannot be written into a solar calendar as a fixed date.
What happens if the birthday is the 30th and that month has only 29 days?
The last day of the same month is used — the 29th. Rolling forward to the 1st of the next month would move the birthday into a different lunar month altogether, which is a bigger change than moving it by a day. The list and the calendar entry both note the years where this happened, so nothing is adjusted silently.
How is a leap-month birthday handled?
If the year repeats the same month, the leap month is used. Otherwise the regular month of that number is used and the row is marked. Leap months return only every ten to thirty-odd years, so insisting on the leap month would leave most years without a birthday at all — which is why families settle on the regular month in practice.
Why is it one event per year instead of a repeating event?
Calendar recurrence rules are defined on the solar calendar: same date each year, third Tuesday of the month, and so on. A lunar date matches none of those patterns, so the file carries a separate dated event for each year in the list. When the list runs out, download it again for the next stretch.
Does the birthday I type get sent anywhere?
No. The conversion and the calendar file are both produced by this page in your browser; the tool makes no request with what you enter, and stores nothing, so a reload clears it. The file is written to your device and it is up to you where it goes from there.
How far ahead can it calculate?
Lunar years 1900 to 2049. The Korean lunar calendar is an astronomical table rather than a formula, so dates past the end of that table are not extrapolated — the list stops at 2049 and says so.
Does it show an age as well?
It shows which birthday each one is — the 36th, the 60th — but not an age in years. A lunar birthday and a solar birthday can sit almost a month apart, so for the weeks between them a count made on the lunar birthday and the everyday age from a solar date of birth disagree by one. The age calculator answers that question from a solar date.
Can it be used for a memorial rite (제사) instead?
Yes — enter the lunar date of death and change the name of the entry; the yearly list works the same way. Families that hold the rite on the eve should subtract one day from the dates shown, rather than entering a lunar date that has already been shifted back, which would move it by two.