Born outside Korea

There is one rule to remember. Enter the time the clocks showed where you were born, on the day you were born, exactly as it appears on your birth certificate or hospital record. You don't need to convert it to Korea time or to today's time zone. We work out from the date and place whether daylight saving time was in force and which standard time applied.

What if you convert the time to Korea time and pick South Korea as the birthplace? The moment of birth is the same, so the year and month pillars usually stay put. The day and hour pillars, though, are then built on Seoul's longitude and the Korean calendar date, and can come out different from your own.

Under birthplace, choose "Anywhere else", pick your country from the list, then search for your city. The 34,149 cities in the list come from GeoNames, and each one carries its longitude and its IANA time zone. If your city isn't listed, you can choose the country alone; we then use that country's most populous city and say so in your result's calculation notes. In a wide country the longitude gap between cities can change the hour pillar, so pick your own city or the nearest one you can find.

Standard time has changed more often than most people expect. For births outside Korea we use the IANA time zone database, a shared record of time zone changes around the world, to find the standard time and any daylight saving in force at the moment you were born. Before a place adopted official standard time, we use the local mean time it kept.

To tell daylight saving apart, we compare the clock offset with the weeks before and after. A short stretch where clocks ran an hour ahead counts as daylight saving, and we take that hour back out. A long-running change, such as the year-round summer time Britain kept from autumn 1968 to autumn 1971, is treated as the standard time of its day. How we handle the hour that is skipped or repeated when clocks change is set out in our calculation guide, with Korean examples in our daylight saving guide.

By default we apply the True Solar Time Adjustment, which shifts the clock to match the sun at your birthplace, from its longitude and the date; the formula is in our calculation guide. For a birth abroad, the point to know is that the meridian comes from the local standard time. A standard time one hour ahead of UTC sits on 15° east, and New York's, five hours behind UTC, sits on 75° west, whatever the summer clocks showed.

The adjustment only touches the day and hour pillars. The year and month pillars compare the real moment of birth with the solar term boundary, unadjusted. We also add the equation of time, between about −14 and +16 minutes over the year, which depends only on the date and time, not on where you were born. Half-hour and quarter-hour time zones, and places near the date line, go through the same formula. The minutes in the table below are the longitude part, before the equation of time.

When a whole country shares one standard time, births at its far edge get a large shift. We calculate every mainland Chinese birth from October 1, 1949 on China Standard Time, so choosing Urumqi in the far west moves the clock by −130 minutes for longitude alone and can change the hour pillar by one step. Earlier births follow the time zone the region actually used then.

The same moment carries a different date depending on where it is written down. The 2026 Start of Spring (Lichun) came at 05:02 on February 4 in Korea, which was 15:02 on February 3 in New York, a day earlier. The year and month pillars change at that single moment, so a baby born in New York at 15:02 on February 3, 2026 or later is already in the 丙午 (Bing Wu) year. Read a Korea-time table alone and you might think "before February 4, so still 乙巳 (Yi Si)", which would be off.

That's why your result shows the solar term boundary in your birthplace's local time, and checks whether you were born on a boundary day by your birthplace's date. A solar term is one moment for the whole planet, so being born in the Southern Hemisphere doesn't flip the order of the seasons in the chart.

The day pillar works the other way round: it follows the local date. We take the local clock time, remove any daylight saving, add the longitude shift and the equation of time, and build the day pillar from the date that time falls on. So if you were born late in the evening where you were, the day pillar is that local date, even though Korea had already moved on to the next day. If the adjusted time is 11 pm or later, the default single Zi hour rule moves the day pillar to the next day.

Where a time zone jumped across the International Date Line and a whole date was skipped, such as December 30, 2011 in Samoa, we don't accept that date and ask you to check the day before or after.

We accept a lunar birth date only if you were born in South Korea, North Korea, China, Taiwan, Hong Kong, Macao, Singapore and Malaysia. Choose any other country and we'll ask for the solar (Gregorian) date. We don't take Vietnamese lunar dates: Vietnam reckons new moons on UTC+7, so month starts and leap months differ in some years. Births in China, Taiwan, Hong Kong, Macao, Singapore or Malaysia are converted with the Chinese calendar used there, which runs on UTC+8, and births in the two Koreas with the Korean one. The two now and then begin a month on different days, and in 2012 and 2017 the leap month differs: 3 and 5 in the Korean calendar, 4 and 6 in the Chinese. Enter the lunar date as the calendar of your birthplace shows it. If you know your Gregorian birthday, entering it is the simpler route; if your lunar birthday falls in a leap month, see our leap month guide.

If you were born outside Korea and don't know the time, we set the year pillar, month pillar and Luck Pillar start age from local clock noon, including daylight saving if it applied that day. Births in Korea are judged at standard-time noon without daylight saving, so on a daylight saving day the two rules sit an hour apart. If you were born on a solar term boundary day without a known time, your calculation notes flag it.