This site’s free saju calculator casts your 사주팔자 (saju palja, 四柱八字), the four pillars and eight characters, from exact solar-term times. Use the free Ba Zi calculator or open the chart directly in the app at app.butcherboy.com.sg/chart. Saju and Ba Zi (八字 bāzì) are the same system, so the same calculator serves both.
For a Korean birth, enter three things:
- Date of birth, as the solar (Gregorian) date.
- Time of birth, as the clock showed it, adjusted only as described below.
- Place of birth: “Tokyo / Seoul (UTC+9)”. Other options include “Singapore / Hong Kong / China (UTC+8)”, India, London, Central Europe, US Eastern, US Pacific and Sydney.
Every birth is converted to UTC+8 internally, and the solar terms are exact to the minute for 1930 to 2035. The rest of this page is about getting the time you type in right, because that is where saju charts go wrong. For what else separates an accurate tool from a rough one, see free Ba Zi calculators compared.
What the saju calculator does, and what it does not
It applies the time zone you choose. It does not apply a longitude (true solar time) correction, and it does not apply daylight saving time automatically. Both are deliberate: practitioners disagree on the first, and the second depends on the clock in force on your birth date. If either applies to you, adjust the clock time yourself before you enter it. The general case for and against online chart tools is in how accurate are Ba Zi calculators.
The four time questions that change a saju chart
1. The year changes at Li Chun, not 1 January or Seollal
The year pillar turns at Li Chun (立春 lìchūn), in Korean 입춘 (ipchun, 立春), the start of the solar year. Saju uses the same boundary as Ba Zi. In 2026 it fell on 2026-02-04 at 04:01; in 2027 it falls on 2027-02-04 at 09:45, both in Singapore time (UTC+8). A January birth belongs to the previous year’s pillar whatever the lunar calendar says. The calculator handles this boundary itself; you only need to enter the correct date.
2. Months change at the solar terms
Month pillars change at the twelve jie solar terms, 절기 (jeolgi, 節氣), not on the first of the calendar month. In 2026, for example, the 戊戌 (Wù Xū) month began at 寒露 (Hánlù) on 2026-10-08 at 14:28. A birth a few hours either side of a term lands in a different month pillar, and the month branch sets the season the whole reading is weighed against. This is the main reason to use a minute-exact calculator rather than a printed table. The full 2026 list is on 2026 Ba Zi monthly pillars.
3. Seoul’s 32-minute question: schools differ
Korean Standard Time (UTC+9) is set on the 135°E meridian. Seoul sits near 127°E, so local solar time in Seoul runs about 32 minutes behind the clock. Many saju practitioners correct for this; others do not. It is a genuine school difference, not an error on either side.
- If your practitioner corrects: subtract about 32 minutes from the clock time, then enter that with “Tokyo / Seoul (UTC+9)”.
- If they do not: enter the clock time as it was.
For most births the two give the same chart. It matters when the birth falls within about half an hour of an hour-pillar boundary, and most of all near midnight, where the day pillar can change too (see the Zi hour). If yours is close, cast it both ways and note which pillars move.
4. Older Korean clocks: UTC+8:30 and daylight saving
Korea used UTC+8:30 from 1954 to 1961, and observed daylight saving time in 1987 and 1988. Check the clock in force at birth before casting.
- Born 1954 to 1961: the list has no UTC+8:30 option. Add 30 minutes to the clock time and enter it with “Tokyo / Seoul (UTC+9)”, or subtract 30 minutes and enter it with “Singapore / Hong Kong / China (UTC+8)”. Both give the same instant.
- Born 1987 or 1988: if the birth fell inside the daylight-saving period, take the daylight-saving offset off the clock time before entering it. The calculator will not do this for you.
Apply the 32-minute correction, if you use it, on top of these.
Check before you enter
- Is the date the solar date? Convert a lunar birthday first.
- Is the time from a record, or from memory? Note how sure you are.
- Was the birth in Korea under UTC+8:30 (1954 to 1961) or in a daylight-saving year (1987, 1988)? Adjust as above.
- Does your practitioner use the Seoul 32-minute correction? Decide before you cast, not after you see the result.
- Is the birth near Li Chun, a solar term, or an hour boundary? Cast the alternatives and compare.
Without a birth time, the hour pillar cannot be fixed, but three of the four pillars still stand. Why the hour matters is covered in birth hour and the hour pillar.
Reading the output in saju terms
The calculator labels the chart in Ba Zi vocabulary. Here is how it maps to the Korean terms a saju practitioner uses:
| On the chart | Saju term | Hanja |
|---|---|---|
| The four pillars: year, month, day, hour | 사주 saju | 四柱 |
| The eight characters together | 팔자 palja | 八字 |
| Top row: heavenly stems | 천간 cheongan | 天干 |
| Bottom row: earthly branches | 지지 jiji | 地支 |
| Day Master, the stem of the day pillar | 일간 ilgan | 日干 |
| Wood, Fire, Earth, Metal, Water | 오행 ohaeng | 五行 |
The calculator does the job a 만세력 (manseryeok, 萬歲曆), the perpetual calendar, once did by hand. Interpreting the result is a separate step: the order a reader follows is set out in saju reading, the Korean readings of all 22 characters are tabled in saju palja, and how saju compares with Ba Zi is on the saju hub.
Cast your chart
Find your eight characters with the time zone right: plot them free with the saju calculator, choosing “Tokyo / Seoul (UTC+9)” for a Korean birth and adjusting the clock time first if the notes above apply.