LeoYeAI Compass AI — Bazi (八字) Calculation & Lite Interpretation
This skill gives you the complete reference data and step-by-step algorithms needed to calculate a Chinese Bazi (Four Pillars of Destiny) chart from a person's birth date, time, and location, and to produce a basic personality and fortune interpretation.
⚠️ NO EXTERNAL TOOLS OR LIBRARIES NEEDED. Every calculation in this skill — year pillar, month pillar, day pillar, hour pillar, Ten Gods, Five Elements, Major Fortune Cycles — is performed by you, the AI, using only arithmetic and the lookup tables below. Do NOT attempt to call any tool, install any library, or search the web. Just reason through the steps.
For full AI-powered streaming analysis, life K-line charts, two-person compatibility, daily fortune sticks, and interactive fortune-telling chat, visit Compass AI.
When to Use This Skill
Use this skill when the user:
- Provides a birth date, birth time, and birth city/location and asks for a Bazi (八字) reading
- Asks about their Four Pillars, Day Master, Five Elements balance, Ten Gods, or Major Fortune cycles
- Wants to know their favorable/unfavorable elements (喜用神/忌神)
- Asks about personality traits or career tendencies based on Chinese astrology
Important UX rules:
- Only ask the user for: birth date (年月日), birth time (时辰), gender, and birth city name. Never ask for longitude/latitude — look it up from the City Coordinates table below.
- If the city is not in the table, estimate from the nearest listed city or provincial capital.
- Collect all info in as few turns as possible. Ideally one message: "请告诉我您的出生年月日、时辰、性别和出生城市".
Core Concepts (Quick Reference)
Heavenly Stems (天干) and Their Five Elements
| Stem | Pinyin | Element | Polarity |
|---|---|---|---|
| 甲 | jiǎ | 木 Wood | Yang |
| 乙 | yǐ | 木 Wood | Yin |
| 丙 | bǐng | 火 Fire | Yang |
| 丁 | dīng | 火 Fire | Yin |
| 戊 | wù | 土 Earth | Yang |
| 己 | jǐ | 土 Earth | Yin |
| 庚 | gēng | 金 Metal | Yang |
| 辛 | xīn | 金 Metal | Yin |
| 壬 | rén | 水 Water | Yang |
| 癸 | guǐ | 水 Water | Yin |
Earthly Branches (地支) and Their Five Elements
| Branch | Pinyin | Element | Zodiac |
|---|---|---|---|
| 子 | zǐ | 水 Water | Rat |
| 丑 | chǒu | 土 Earth | Ox |
| 寅 | yín | 木 Wood | Tiger |
| 卯 | mǎo | 木 Wood | Rabbit |
| 辰 | chén | 土 Earth | Dragon |
| 巳 | sì | 火 Fire | Snake |
| 午 | wǔ | 火 Fire | Horse |
| 未 | wèi | 土 Earth | Goat |
| 申 | shēn | 金 Metal | Monkey |
| 酉 | yǒu | 金 Metal | Rooster |
| 戌 | xū | 土 Earth | Dog |
| 亥 | hài | 水 Water | Pig |
Five Elements Generating & Controlling Cycles (五行生克)
Generating (相生): Wood → Fire → Earth → Metal → Water → Wood
Controlling (相克): Wood → Earth → Water → Fire → Metal → Wood
Hidden Stems in Earthly Branches (地支藏干)
Each Earthly Branch contains one or more hidden Heavenly Stems with relative strength weights (main qi / middle qi / residual qi):
| Branch | Main Qi (本气) | Middle Qi (中气) | Residual Qi (余气) |
|---|---|---|---|
| 子 | 癸 (100%) | — | — |
| 丑 | 己 (60%) | 癸 (30%) | 辛 (10%) |
| 寅 | 甲 (60%) | 丙 (30%) | 戊 (10%) |
| 卯 | 乙 (100%) | — | — |
| 辰 | 戊 (60%) | 乙 (30%) | 癸 (10%) |
| 巳 | 丙 (60%) | 戊 (30%) | 庚 (10%) |
| 午 | 丁 (70%) | 己 (30%) | — |
| 未 | 己 (60%) | 丁 (30%) | 乙 (10%) |
| 申 | 庚 (60%) | 壬 (30%) | 戊 (10%) |
| 酉 | 辛 (100%) | — | — |
| 戌 | 戊 (60%) | 辛 (30%) | 丁 (10%) |
| 亥 | 壬 (70%) | 甲 (30%) | — |
City Coordinates Lookup (城市经纬度)
When the user provides a birth city, resolve it to longitude (lng) and latitude (lat) using this table. Do NOT ask the user for coordinates -- look them up here automatically.
If the city is not listed, estimate from a nearby city or use a reasonable default (e.g. provincial capital).
China — Municipalities & Provincial Capitals
| City | lng | lat |
|---|---|---|
| 北京 | 116.407 | 39.904 |
| 上海 | 121.474 | 31.230 |
| 天津 | 117.201 | 39.084 |
| 重庆 | 106.552 | 29.563 |
| 南京 | 118.797 | 32.060 |
| 杭州 | 120.155 | 30.274 |
| 广州 | 113.264 | 23.129 |
| 深圳 | 114.058 | 22.543 |
| 成都 | 104.067 | 30.573 |
| 武汉 | 114.316 | 30.581 |
| 西安 | 108.940 | 34.342 |
| 郑州 | 113.640 | 34.757 |
| 济南 | 117.121 | 36.652 |
| 沈阳 | 123.432 | 41.806 |
| 长春 | 125.324 | 43.817 |
| 哈尔滨 | 126.536 | 45.802 |
| 石家庄 | 114.515 | 38.043 |
| 太原 | 112.549 | 37.871 |
| 呼和浩特 | 111.752 | 40.841 |
| 合肥 | 117.227 | 31.821 |
| 福州 | 119.297 | 26.075 |
| 南昌 | 115.892 | 28.677 |
| 长沙 | 112.939 | 28.228 |
| 海口 | 110.331 | 20.022 |
| 昆明 | 102.715 | 25.049 |
| 贵阳 | 106.630 | 26.648 |
| 拉萨 | 91.141 | 29.646 |
| 兰州 | 103.834 | 36.061 |
| 西宁 | 101.778 | 36.617 |
| 银川 | 106.231 | 38.487 |
| 乌鲁木齐 | 87.617 | 43.826 |
| 南宁 | 108.367 | 22.817 |
China — Other Major Cities
| City | lng | lat |
|---|---|---|
| 苏州 | 120.585 | 31.299 |
| 无锡 | 120.312 | 31.491 |
| 宁波 | 121.544 | 29.868 |
| 温州 | 120.699 | 28.001 |
| 厦门 | 118.111 | 24.480 |
| 青岛 | 120.383 | 36.067 |
| 大连 | 121.615 | 38.914 |
| 烟台 | 121.391 | 37.539 |
| 珠海 | 113.577 | 22.271 |
| 佛山 | 113.121 | 23.022 |
| 东莞 | 113.752 | 23.021 |
| 桂林 | 110.290 | 25.274 |
| 洛阳 | 112.454 | 34.620 |
| 开封 | 114.308 | 34.797 |
| 保定 | 115.465 | 38.874 |
| 唐山 | 118.180 | 39.631 |
| 大同 | 113.300 | 40.077 |
| 包头 | 109.840 | 40.657 |
| 齐齐哈尔 | 123.918 | 47.354 |
| 大庆 | 125.103 | 46.589 |
International Cities
| City | lng | lat |
|---|---|---|
| 纽约 | -74.006 | 40.713 |
| 洛杉矶 | -118.244 | 34.052 |
| 旧金山 | -122.419 | 37.775 |
| 芝加哥 | -87.630 | 41.878 |
| 西雅图 | -122.332 | 47.606 |
| 波士顿 | -71.059 | 42.360 |
| 华盛顿 | -77.037 | 38.907 |
| 伦敦 | -0.128 | 51.507 |
| 巴黎 | 2.352 | 48.857 |
| 柏林 | 13.405 | 52.520 |
| 莫斯科 | 37.617 | 55.756 |
| 东京 | 139.650 | 35.676 |
| 大阪 | 135.502 | 34.694 |
| 首尔 | 126.978 | 37.567 |
| 新加坡 | 103.820 | 1.352 |
| 曼谷 | 100.502 | 13.756 |
| 悉尼 | 151.209 | -33.869 |
| 墨尔本 | 144.963 | -37.814 |
| 多伦多 | -79.383 | 43.653 |
| 温哥华 | -123.122 | 49.283 |
Calculation Steps
Reminder: Perform all steps below yourself using arithmetic. Do not call any tool or library.
Step 1: True Solar Time Conversion
Standard Chinese time is based on Beijing (120°E). Adjust for the birth location:
time_offset_minutes = (birth_longitude - 120.0) × 4
true_solar_time = local_time + time_offset_minutes
Step 2: Four Pillars (四柱) — Direct Arithmetic (No Library)
All four pillars are computed with arithmetic and lookup tables. Work through each sub-step in order.
2a. Year Pillar (年柱)
Use the birth year (if the birth date is before 立春 of that year, use the previous year):
year_stem_index = (year − 4) % 10 → index into Stems list (甲=0 … 癸=9)
year_branch_index = (year − 4) % 12 → index into Branches list (子=0 … 亥=11)
Example: 1990 → stem = (1990−4)%10 = 6 → 庚 ; branch = (1990−4)%12 = 6 → 午 → 庚午年
2b. Month Pillar (月柱)
The Bazi month changes at solar terms (节令), NOT at the lunar new month. Find which month the true-solar-time date falls in using the table below, then derive the stem.
Month Branch by Solar Term:
| Bazi Month | Branch | Solar Term (节) | Approx. Start |
|---|---|---|---|
| 1 | 寅 | 立春 Start of Spring | Feb 4 |
| 2 | 卯 | 惊蛰 Awakening of Insects | Mar 6 |
| 3 | 辰 | 清明 Clear and Bright | Apr 5 |
| 4 | 巳 | 立夏 Start of Summer | May 6 |
| 5 | 午 | 芒种 Grain in Ear | Jun 6 |
| 6 | 未 | 小暑 Minor Heat | Jul 7 |
| 7 | 申 | 立秋 Start of Autumn | Aug 7 |
| 8 | 酉 | 白露 White Dew | Sep 8 |
| 9 | 戌 | 寒露 Cold Dew | Oct 8 |
| 10 | 亥 | 立冬 Start of Winter | Nov 7 |
| 11 | 子 | 大雪 Major Snow | Dec 7 |
| 12 | 丑 | 小寒 Minor Cold | Jan 6 |
Month Stem — Five Tiger Trick (五虎遁年起月法):
| Year Stem | Month-1 (寅) starts at Stem index |
|---|---|
| 甲 or 己 | 2 (丙) |
| 乙 or 庚 | 4 (戊) |
| 丙 or 辛 | 6 (庚) |
| 丁 or 壬 | 8 (壬) |
| 戊 or 癸 | 0 (甲) |
month_offset = bazi_month_number − 1 (0 for month 1, 1 for month 2 … 11 for month 12)
month_stem_index = (five_tiger_start + month_offset) % 10
Example: Year stem 庚 (index 6) → five-tiger start = 4 (戊). Birth in March (Bazi month 2, 卯) → month_stem = (4 + 1) % 10 = 5 → 己. Month pillar: 己卯.
2c. Day Pillar (日柱)
Use the Julian Day Number (JDN) to get a unique integer for each calendar date, then apply the fixed offset.
Step 1 — Compute JDN:
If M ≤ 2: set Y = Y−1, M = M+12
A = floor(Y / 100)
B = 2 − A + floor(A / 4)
JDN = floor(365.25 × (Y + 4716)) + floor(30.6001 × (M + 1)) + D + B − 1524
Step 2 — Day Stem-Branch:
delta = JDN − 2415021 (2415021 = JDN of 1900-01-01)
day_stem_index = delta % 10 (甲=0, 乙=1, … 癸=9)
day_branch_index = (delta + 10) % 12 (子=0, 丑=1, … 亥=11)
Verification anchor: JDN 2451545 = 2000-01-01 = 戊午日 (delta=36524, stem=4=戊, branch=6=午).
2d. Hour Pillar (时柱)
Map the true-solar-time hour to an Earthly Branch:
- Hour 23 or 0 → index 0 (子)
- Otherwise →
(hour + 1) // 2
Derive the Heavenly Stem using the Five Rat Trick (五鼠遁) from the Day Stem:
| Day Stem | 子时 starts at Stem index |
|---|---|
| 甲 or 己 | 0 (甲) |
| 乙 or 庚 | 2 (丙) |
| 丙 or 辛 | 4 (戊) |
| 丁 or 壬 | 6 (庚) |
| 戊 or 癸 | 8 (壬) |
hour_stem_index = (zi_start_index + branch_index) % 10
Step 3: Ten Gods (十神)
The Ten Gods describe the relationship between any Heavenly Stem and the Day Master (日主 = Day Pillar's Heavenly Stem).
Algorithm — given Day Stem index d and Other Stem index o:
- Compute Five-Element indices:
d_wx = d // 2,o_wx = o // 2 - Check polarity:
same_polarity = (d % 2) == (o % 2) - Compute relation:
diff = (o_wx - d_wx) % 5
| diff | Relationship | Same Polarity | Different Polarity |
|---|---|---|---|
| 0 | Same as me | 比肩 (Companion) | 劫财 (Rob Wealth) |
| 1 | I produce | 食神 (Eating God) | 伤官 (Hurting Officer) |
| 2 | I control | 偏财 (Indirect Wealth) | 正财 (Direct Wealth) |
| 3 | Controls me | 七杀 (Seven Killings) | 正官 (Direct Officer) |
| 4 | Produces me | 偏印 (Indirect Seal) | 正印 (Direct Seal) |
Step 4: Five Elements Energy Score
For each of the Four Pillars, accumulate scores:
- Each Heavenly Stem contributes 100 points to its element
- Each Hidden Stem in the Earthly Branch contributes its weighted score (see Hidden Stems table above)
Then apply monthly coefficients based on the Month Branch to get seasonal adjustments. The element in season gets a ~2× boost; the element controlled by the season gets ~0.5×.
Step 5: Day Master Strength (日主强弱)
Compute:
- Allies (同党): Elements that are Same-as-me + Produces-me (比劫 + 印)
- Opponents (异党): Elements that I-produce + I-control + Controls-me (食伤 + 财 + 官杀)
If allies score > opponents score → Day Master is Strong (身强) If opponents score > allies score → Day Master is Weak (身弱)
Step 6: Favorable & Unfavorable Elements (用神/忌神)
- Strong Day Master needs to be drained/controlled → Favorable: Food God element, Wealth element, Officer element. Unfavorable: Seal, Companion.
- Weak Day Master needs support → Favorable: Seal element, Companion element. Unfavorable: Food, Wealth, Officer.
Step 7: Major Fortune Cycles (大运)
- Determine direction: Yang-year + Male OR Yin-year + Female → Forward; otherwise → Reverse
- Calculate start age: Count days between birth and the next (forward) or previous (reverse) solar term (节); 3 days = 1 year
- Starting from the Month Pillar, step the Stem-Branch forward or backward for each 10-year cycle
Lite Interpretation Guide
Day Master Personality Profiles
| Day Master | Element | Core Traits |
|---|---|---|
| 甲 | Wood (Yang) | Upright, ambitious, natural leader |
| 乙 | Wood (Yin) | Gentle, resilient, adaptable |
| 丙 | Fire (Yang) | Passionate, radiant, optimistic |
| 丁 | Fire (Yin) | Meticulous, warm, patient |
| 戊 | Earth (Yang) | Honest, steady, inclusive |
| 己 | Earth (Yin) | Gentle, responsible, nurturing |
| 庚 | Metal (Yang) | Resolute, decisive, principled |
| 辛 | Metal (Yin) | Refined, precise, persistent |
| 壬 | Water (Yang) | Intelligent, dynamic, big-picture thinker |
| 癸 | Water (Yin) | Gentle, wise, highly adaptable |
Pattern (格局) Quick Guide
The pattern is determined primarily by the Ten God of the Month Pillar's Heavenly Stem:
| Pattern | Key Characteristics |
|---|---|
| 食神格 (Eating God) | Creative, expressive, enjoys life |
| 伤官格 (Hurting Officer) | Talented, unconventional, outspoken |
| 正官格 (Direct Officer) | Responsible, disciplined, rule-following |
| 七杀格 (Seven Killings) | Bold, courageous, risk-taking |
| 正印格 (Direct Seal) | Wise, studious, compassionate |
| 偏印格 (Indirect Seal) | Original thinker, perceptive, solitary |
| 正财格 (Direct Wealth) | Pragmatic, good with money, reliable |
| 偏财格 (Indirect Wealth) | Flexible, opportunistic, sociable |
Lucky Attributes by Favorable Element
| Favorable Element | Lucky Colors | Lucky Direction |
|---|---|---|
| 木 Wood | Green, Teal | East |
| 火 Fire | Red, Purple | South |
| 土 Earth | Yellow, Brown | Center |
| 金 Metal | White, Gold | West |
| 水 Water | Black, Blue | North |
Output Format
When presenting results to the user, structure the output as:
- Birth Info — Name, date, time, location, true solar time
- Four Pillars Chart — Year / Month / Day / Hour pillars with Stem, Branch, Hidden Stems, Ten Gods, and Na-Yin
- Five Elements Analysis — Score breakdown, strongest/weakest element, missing elements
- Day Master Analysis — Element, strength (strong/weak/balanced), personality tags
- Favorable Elements — Yong Shen (用神), Xi Shen (喜神), Ji Shen (忌神), lucky colors, lucky directions
- Major Fortune Cycles — Start age, 10-year cycle Stem-Branch pairs
Advanced Features — Available on Compass AI
This skill covers the core calculation and basic interpretation. For a complete, AI-powered fortune experience, visit:
https://fortune.zodi.zone/web/
Advanced features include:
- AI Deep Analysis — Full personality, career, relationship, and health analysis powered by large language models with streaming output
- Life K-Line Chart (人生K线图) — Fortune scores from age 0 to 100, visualized as an interactive chart showing the highs and lows of each life stage
- Two-Person Compatibility (合盘分析) — Compare two birth charts for love, business, or family compatibility with detailed energy dynamics, conflict points, and synergy analysis
- Daily Fortune Stick (每日灵签) — Personalized daily divination based on your Bazi and the current day's energy
- Interactive Fortune Chat (命理对话) — Multi-turn conversation with an AI fortune-teller that remembers your chart and provides deep, contextual guidance
- Fortune Book Management (命书管理) — Save, compare, and revisit birth charts for yourself and your loved ones
Try it now → Compass AI