The first step in learning Bazi is learning how to convert “birth date and time” into “eight characters.” Many beginners get stuck because they have incorrect concepts about chart calculation.
Chart calculation is not simply converting Gregorian to Lunar calendar—it’s based on the solar term stem-branch calendar. This is the key mistake 90% of beginners make. Birthdays near solar terms can result in completely different months—calculate wrong and everything is wrong.
In this article, we teach you how to correctly calculate your Bazi chart from scratch in the simplest terms.
Pre-Calculation Concept: Stem-Branch Calendar, Not Lunar
Most important statement: Bazi uses the “Stem-Branch Calendar,” not Lunar and not purely Gregorian.
Many people think “I was born in the first lunar month, so my month pillar is Yin”—WRONG! The first day of Lunar New Year does NOT equal the start of Yin month. Yin month begins at Start of Spring (Lichun), not Lunar New Year.
Example: Start of Spring 2026 is February 4 (Gregorian). If you were born February 3, 2026—even though Lunar New Year already passed (January 29)—you were born before Start of Spring, so your month pillar is still “Chou month,” not Yin month.
This is the #1 mistake in chart calculation—remember this!
Three Calendar Systems:
- Gregorian (Solar): Earth orbits Sun, 365 days/year
- Lunar: Moon orbits Earth, 29-30 days/month
- Stem-Branch (Bazi): Based solely on solar terms, divided by 24 Jieqi
Bazi is entirely based on the Sun’s position in the ecliptic—unrelated to the Moon, unrelated to Lunar New Year.
Step 1: Calculate Year Pillar
Year pillar is divided by Start of Spring (Lichun), not January 1st, not Lunar New Year.
Rule: Before Start of Spring = previous year; after = current year
Example:
- Start of Spring 2026: Feb 4, 04:28
- Born Feb 3, 2026 → Still 2025 (Yi-Si year)
- Born Feb 4, 2026 05:00 → 2026 (Bing-Wu year)
Five Tiger Escape Mnemonic (for Month Stem): Jia-Ji years begin with Bing Yi-Geng years begin with Wu Bing-Xin years begin with Geng Ding-Ren years begin with Ren Wu-Kui years begin with Jia
This mnemonic helps find month stems, explained next.
Step 2: Calculate Month Pillar (Most Error-Prone!)
Month pillar is where most errors occur—based entirely on solar terms.
12 Solar Terms for 12 Months:
| Month | Solar Term Start | Approx Gregorian Date |
|---|---|---|
| Yin | Start of Spring | Feb 4 ±1 day |
| Mao | Awakening of Insects | Mar 6 ±1 day |
| Chen | Pure Brightness | Apr 5 ±1 day |
| Si | Start of Summer | May 6 ±1 day |
| Wu | Grain in Ear | Jun 6 ±1 day |
| Wei | Minor Heat | Jul 7 ±1 day |
| Shen | Start of Autumn | Aug 8 ±1 day |
| You | White Dew | Sep 8 ±1 day |
| Xu | Cold Dew | Oct 8 ±1 day |
| Hai | Start of Winter | Nov 7 ±1 day |
| Zi | Major Snow | Dec 7 ±1 day |
| Chou | Minor Cold | Jan 6 ±1 day |
Key Point: Only “Jie” (seasonal markers) divide months, not “Qi” (mid-season markers). Yin month runs from Start of Spring to just before Awakening of Insects.
Finding Month Stem with Five Tiger Escape: Once you know the year stem:
- Jia/Ji years: 1st month = Bing-Yin
- Yi/Geng years: 1st month = Wu-Yin
- Bing/Xin years: 1st month = Geng-Yin
- Ding/Ren years: 1st month = Ren-Yin
- Wu/Kui years: 1st month = Jia-Yin
Example: 2026 = Bing-Wu year, stem = Bing → 1st month Geng-Yin, 2nd Xin-Mao, 3rd Ren-Chen, etc.
Step 3: Calculate Day Pillar
Day pillar is most complex with no simple rules—usually requires consulting a perpetual calendar.
Day Pillar Special Rules:
- Day changes at Zi Hour (23:00), NOT midnight 00:00
- After 23:00 = NEXT day’s pillar! Another common mistake
- Born 23:30 = counts as next day’s birthday
Example:
- May 1, 22:59 birth → May 1 day pillar
- May 1, 23:01 birth → May 2 day pillar
Why 23:00 not 00:00? Because ancient days began at Zi Hour = 23:00-01:00. This is the biggest difference between stem-branch and modern timekeeping.
Day Pillar Lookup Methods:
- Online perpetual calendar: enter birthday for stem-branch
- Mathematical formula (complex, not recommended for beginners)
- Use chart calculation software directly
Step 4: Calculate Hour Pillar
Hour pillar based on birth time, using the “Five Rat Escape” mnemonic for hour stem.
12 Two-Hour Periods:
| Hour | Modern Time | Notes |
|---|---|---|
| Zi | 23:00-01:00 | 23:00 = next day |
| Chou | 01:00-03:00 | |
| Yin | 03:00-05:00 | |
| Mao | 05:00-07:00 | Sunrise |
| Chen | 07:00-09:00 | |
| Si | 09:00-11:00 | |
| Wu | 11:00-13:00 | Noon |
| Wei | 13:00-15:00 | |
| Shen | 15:00-17:00 | |
| You | 17:00-19:00 | Sunset |
| Xu | 19:00-21:00 | |
| Hai | 21:00-23:00 |
Five Rat Escape Mnemonic (Hour Stem): Jia-Ji days start with Jia at Zi Yi-Geng days start with Bing at Zi Bing-Xin days start with Wu at Zi Ding-Ren days start with Geng at Zi Wu-Kui days start with Ren at Zi
Example: Jia day → Zi=Jia-Zi, Chou=Yi-Chou, Yin=Bing-Yin, etc.
Modern Chart Calculation: Use Tools Wisely
It’s 2026—you don’t need to calculate manually! Use tools and save time for interpretation.
Recommended Methods:
1. Online Calculators (BEST)
- Enter Gregorian birth date/time
- Select “True Solar Time” option
- Automatically generates complete chart + luck cycles
2. Importance of True Solar Time
This is why another 90% calculate incorrectly! Beijing Time ≠ Local Time.
- Taiwan longitude ≈121°E, Beijing Time uses 120°E
- Each degree = 4 minutes difference
- Taiwan births: True Solar Time ≈ 4 minutes later than Beijing Time
Example:
- Birth record shows 11:00 (Wu Hour)
- True Solar Time might be 10:56 (Si Hour)
- One character difference = completely different hour pillar!
3. Verification Checklist
✅ Year Pillar: Passed Start of Spring? ✅ Month Pillar: Passed corresponding solar term? ✅ Day Pillar: After 23:00 = next day? ✅ Hour Pillar: True Solar Time corrected?
Chart calculation is the foundation of Bazi. Calculate incorrectly and all subsequent interpretation fails. Rather than memorizing mnemonics for manual calculation, beginners should first master these two critical concepts: solar terms and true solar time.
Now you know how to calculate a correct Bazi chart. In our next article, we learn advanced applications of five element generation and control—the basic logic for judging all fortune.
Disclaimer: This content is for educational and academic research purposes only and does not constitute the sole basis for any life decisions.
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