Korean Calendar Year (Dangi Era)

Give the page a Gregorian date and it answers with two Korean readings of that day. The first is the Dangi year, the Gregorian year plus 2333. The second is the same day on the lunisolar calendar: month number, day, a leap month marker when there is one, the Korean written form, the sexagenary name of the year, and the Seollal that opened the lunisolar year in progress. All of it is read from the Intl dangi calendar in the browser, in UTC.

The 2333 comes from the founding of Gojoseon by Dangun, dated to 2333 BC in the Samguk Yusa. South Korea put the count on official paperwork in 1948 and kept it until 31 December 1961; from 1 January 1962 the Western year took over, though Dangi is still carved on cornerstones, monuments and commemorative coins. The lunisolar calendar is a separate machine: months track the new moon and run 29 or 30 days, and a leap month is inserted seven times every nineteen years so the year does not drift away from the seasons.

That is why the two readings sometimes disagree. The lunisolar year only turns at Seollal, which falls between 21 January and 20 February. On 15 January 2026 the Dangi number is already 4359, yet on the lunar calendar the day still belongs to the year that opened on 29 January 2025, and the page says so. Checks you can repeat: 1 August 2026 is the 19th day of the sixth month in the year bing-wu, and 25 July 2025 lands in the leap sixth month. The page does not convert a lunar date back to Gregorian, and it does not compute Korean age reckoning, dropped from official use in 2023.