Cast your four pillars (free)
A four pillars chart turns your birth year, month, day and hour into four stem-and-branch pairs. Enter your birth details here and the page casts those four pillars, your day master and your five-element balance right away. No account, no charge.
What a solar-term boundary is
A solar-term boundary is the instant a major term of the twenty-four solar terms begins — a point fixed by the sun's position, not by the calendar. The year and month pillars of a four pillars chart change at that instant, not on 1 January and not on the first of the month. So two people born on the same 4 February can carry different year pillars, depending on whether they were born before or after the Start of Spring.
Born in January or early February? Your year pillar is last year's
If you were born between 1 January and the Start of Spring (立春) boundary in early February, your year pillar takes the previous year's stem and branch. It is the same logic as a school-year cutoff — in Japan, children born between 1 January and 1 April (hayaumare, the 'early-born') join the school year of children born the year before. The four-pillars year turns at the Start of Spring, not on New Year's Day, so a birth before that moment belongs to the preceding year. A January 2025 birth, for example, carries 甲辰 as its year pillar, not 乙巳.
| Year | Start of Spring (UTC+9 · MM-DD HH:mm) | Year pillar that begins here |
|---|---|---|
| 2020 | 庚子 | |
| 2021 | 辛丑 | |
| 2022 | 壬寅 | |
| 2023 | 癸卯 | |
| 2024 | 甲辰 | |
| 2025 | 乙巳 | |
| 2026 | 丙午 | |
| 2027 | 丁未 | |
| 2028 | 戊申 | |
| 2029 | 己酉 | |
| 2030 | 庚戌 |
Source: National Astronomical Observatory of Japan, Calendar Handbook, "Twenty-four solar terms and miscellaneous days" (2020–2027). 2028–2030 are computed from the same astronomical almanac. Seconds are rounded to the minute. Japan and Korea share UTC+9, so JST and KST tables give the same values.
Why AI chatbots get four pillars charts wrong
A conversational model does not look up an astronomical almanac; it continues a sentence with the stem-and-branch pair that reads most plausibly. But the solar-term instant moves by hours from year to year, and the Start of Spring falls on 3 February in some years and 4 February in others, so judging by the date alone shifts the month pillar — and sometimes the year pillar — by a full position. The table above shows it: in 2021 and 2025 the Start of Spring lands late on 3 February, in 2022 and 2026 in the small hours of 4 February. Nothing but an actual almanac lookup closes that gap, which is why asking the same birth date twice can return two different charts.
This page runs no language model. The solar-term instants come from perpetual-calendar astronomical data, and the standard time of your birthplace is converted to Korean standard time before the pillars are cast (true solar time is not corrected). Every value used is printed under "How this was calculated", so the same details always produce the same chart, for anyone, on any attempt.
Common questions
- How are the four pillars decided?
- The year and month pillars change at solar terms — someone born before the Start of Spring carries the previous year's pillar. The day pillar comes from the calendar date and the hour pillar from the birth time. This page derives all four from perpetual-calendar arithmetic alone.
- I was born right around the Start of Spring — which year pillar applies?
- The boundary is exact to the minute. In 2025 the Start of Spring fell on 3 February at 23:10 (UTC+9), so a birth at 23:05 that same evening carries 甲辰 and a birth at 23:15 carries 乙巳. When a birth falls within an hour of a boundary, this page asks you to double-check the time.
- What if I don't know my birth time?
- The year, month and day pillars can still be cast. The hour pillar cannot, so it is left blank here. An unknown time is never filled in with a guess.
- How is a birth in the 11pm hour (the late Rat hour) handled?
- 23:00 to 01:00 is treated as the Rat hour, but the day pillar of a birth in the 23:00 hour is not rolled forward — it changes only after midnight. Some schools advance the day pillar at 23:00; this page consistently does not, and says so under "How this was calculated".
- Can I enter a lunar calendar birth date?
- Yes — choose "Lunar" and the date is converted to the solar calendar before the pillars are cast. There is no field for a leap month, though, so lunar input is treated as an ordinary month. If you were born in a leap month, look up the Gregorian date and enter it as "Solar" instead.
- Does changing the birthplace change the chart?
- It can, when the birthplace keeps a different standard time from Korea. The birthplace's standard time is converted to Korean standard time before the pillars are cast, so a birth in China shifts by one hour and a birth in Thailand by two. Japan shares Korea's standard time, so no shift is applied there. The exact shift is printed in minutes under "How this was calculated".
- Do you correct for true solar time?
- No. The local standard time of your birthplace is converted to Korean standard time and used as it is. The conversion is printed under "How this was calculated", so you can check it yourself.
- Why does an AI chatbot give me a different chart than this page?
- Because a conversational model does not consult an astronomical almanac — it produces the stem-and-branch pair that reads plausibly. Solar-term instants move each year, so judging by the date alone shifts the month or year pillar by one position. This page derives the pillars from perpetual-calendar arithmetic only and prints the solar-term instant it used, so you can check the arithmetic yourself.