The classical He Tu (河图) system assigns a specific pair of numbers to each of the Five Elements. Knowing your Useful God unlocks your personally auspicious digits.
In Saju and BaZi, your lucky numbers are the He Tu (河图) digit pairs of your Useful God (Yong Shen / 용신) — the element that most benefits your natal chart. The five pairings are: Water = 1 & 6 | Wood = 3 & 8 | Fire = 2 & 7 | Earth = 5 & 0 | Metal = 4 & 9. The numbers of the element that generates your Useful God serve as secondary auspicious digits.
The He Tu (河图, River Map) is a pre-Han cosmological diagram traditionally associated with the mythological figure Fu Xi (僓胜). In its classical form it arranges 55 dots in a pattern of black (yin) and white (yang) groups around a centre. Medieval Chinese cosmologists extracted from these dot patterns a precise mapping of numbers to the Five Elements:
Within each pair, the smaller number is yang (odd) and the larger is yin (even), mirroring the He Tu's black-and-white dot groupings. This is why BaZi practitioners do not assign lucky numbers arbitrarily: the correspondence is a documented feature of classical Chinese cosmology, reproduced in the Shuo Gua zhuan commentary of the I Ching and later systematised in Song-dynasty Neo-Confucian texts.
| Element | Korean / Chinese | He Tu digits | Direction | Season |
|---|---|---|---|---|
| Water | 수 / 水 | 1, 6 | North | Winter |
| Wood | 목 / 木 | 3, 8 | East | Spring |
| Fire | 화 / 火 | 2, 7 | South | Summer |
| Earth | 토 / 土 | 5, 0 (10) | Centre | Inter-season |
| Metal | 군 / 金 | 4, 9 | West | Autumn |
These are fixed correspondences, not estimates. Any source that lists, for example, "7 as a lucky number for a Metal Day Master" without explaining its elemental logic is likely conflating He Tu with pop-numerology frameworks that have no root in BaZi.
The Useful God varies significantly by the season of birth and the overall chart composition. The table below shows representative patterns — not universal rules. A strong (Wang) Day Master in one season may need entirely different support than the same Day Master born in a different season.
| Day Master | Element | Common Useful God (strong chart) | Primary lucky numbers | Secondary lucky numbers |
|---|---|---|---|---|
| Jia 甲 / Yi 乙 | Wood | Metal (controls excess Wood) | 4, 9 | 5, 0 (Earth generates Metal) |
| Bing 乘 / Ding 丁 | Fire | Water (controls excess Fire) | 1, 6 | 4, 9 (Metal generates Water) |
| Wu 戊 / Ji 己 | Earth | Wood (controls excess Earth) | 3, 8 | 1, 6 (Water generates Wood) |
| Geng 庚 / Xin 辖 | Metal | Fire (controls excess Metal) | 2, 7 | 3, 8 (Wood generates Fire) |
| Ren 壬 / Gui 电 | Water | Earth (controls excess Water) | 5, 0 | 2, 7 (Fire generates Earth) |
For a weak Day Master the logic reverses: the Useful God is typically the element that nourishes (generates) the Day Master rather than the element that controls it. This is why reading only the Day Master without the full chart produces unreliable results.
Classical BaZi texts do not specify exactly how He Tu numbers should be applied in modern contexts — that application is a layer of folk practice that developed over centuries. The most commonly cited uses in contemporary Korean and Chinese Saju/BaZi consultation are:
| Context | How the number is applied | Practitioner note |
|---|---|---|
| Floor or unit number | Choose a residence on a floor whose number matches or ends in a lucky digit | Digit sum (e.g., floor 38 = 3+8 = 11 = 1+1 = 2) is sometimes used to reduce multi-digit numbers |
| Phone or ID number | Prefer numbers whose final one or two digits match the Useful God pair | Practical only when choosing from multiple options; not worth significant cost to force |
| Business pricing | Set product or service prices ending in a lucky digit (e.g., ₩9,900 for a Metal-Useful-God business owner) | Most relevant for solo practitioners or small businesses with pricing flexibility |
| Dates for contracts or moves | Select a calendar date (day of month) that is a lucky digit or whose Earthly Branch day carries the Useful God element | Day Earthly Branch analysis is more rigorous than simple digit matching |
| Numerals in usernames or account names | Incorporate lucky digits where a number is part of an identity string | Low-stakes; mainly for personal resonance |
Zodiac-animal lucky numbers (e.g., "Rat = 2 and 3") are a simplified folk tradition unrelated to He Tu. They do not account for your Day Master, Useful God, or chart balance. In formal BaZi and Saju practice, the zodiac animal (year branch) is just one of the eight characters and rarely the most significant one for an adult.
In the He Tu system, Earth corresponds to both 5 and 10 (written as 0 in a single-digit context). Some popular sources list only 5, dropping the paired 10. The classical He Tu explicitly pairs the numbers as 1-6, 2-7, 3-8, 4-9, and 5-10. Both digits of each pair carry the elemental quality equally.
Chart typing in BaZi includes special patterns such as Cong (following) charts, where an extremely dominant element should be followed rather than controlled. In a Cong Qi (following the dominant qi) chart, the "lucky numbers" may actually be those of the dominant element itself, not the controller. These exceptions require a trained practitioner to identify.
The Lo Shu (洛書, River Scroll) is a separate classical diagram — a 3x3 magic square where every row, column, and diagonal sums to 15. Lo Shu numbers (1 through 9 in a fixed grid) are used in feng shui flying-star analysis and some forms of Qi Men Dun Jia, not in BaZi or Saju lucky-number determination. If a source cites "Lo Shu number 4 for your birth year," it is using a different and unrelated system. BaZi lucky numbers come from the He Tu only.
The Day Master tells you the elemental nature of your core self, but the Useful God — which actually determines your lucky numbers — depends on the balance of all eight characters together. Two people with the same Jia Wood (甲) Day Master but born in different months may have completely opposite Useful Gods: a Jia Wood born in the peak of spring (month of Mao, 卫) is strong and may need Metal; a Jia Wood born in autumn (month of You, 鉴) is weak and may need Water or Fire. Their lucky numbers will differ.
This is the core reason that online "lucky number by zodiac sign" tools frequently give inaccurate results for BaZi purposes: they use only one of the eight characters.
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They are the He Tu (河图) digit pairs assigned to your Useful God element. The Useful God is the element that most benefits your natal chart's balance. For example, if your Useful God is Water, your lucky numbers are 1 and 6 — the He Tu pair for Water. These pairings come from a pre-Han cosmological diagram, not from arbitrary assignment.
Accurately determining the Useful God requires reading all eight natal characters alongside the active Luck Pillar and, ideally, the annual stem-branch. The most reliable shortcut is to enter your full birth data (year, month, day, and hour) into a proper BaZi calculator that outputs chart strength and elemental distribution, then check which element is most absent or most needed. For a definitive answer, a practitioner review is recommended because chart exceptions (following charts, special patterns) can reverse the standard logic.
Your natal Useful God is fixed. However, each 10-year Luck Pillar (Daeun / 대운) introduces a new Heavenly Stem and Earthly Branch that may temporarily strengthen or weaken different elements in your chart. During a Luck Pillar that strongly reinforces your Useful God, that element's numbers feel especially relevant. During a Luck Pillar that harms your Useful God, a practitioner may recommend temporarily emphasising the numbers of a protective secondary element.
Yes. Korean Saju (사주) is structurally identical to Chinese BaZi: both use the same Heavenly Stems, Earthly Branches, and Five-Element framework, and both draw lucky-number associations from the same He Tu source. Terminology differs (Korean uses Hangul readings of the classical characters), but the cosmological system is shared.
Many practitioners and clients in East Asian business culture do incorporate elemental number preferences into pricing, launch dates, and property decisions. The practice is taken seriously as a ritual alignment with one's elemental makeup, not as a replacement for financial or strategic analysis. The most common practical application is choosing between roughly equivalent options (e.g., two similar apartment floors) based on lucky-digit alignment.
Yes. In the He Tu system, Earth is paired with 5 and 10 (written as 0 in single-digit contexts). Zero is the reduced form of 10, and both carry Earth energy equally. In practice, practitioners look for digits 5 and 0 in multi-digit numbers when Earth is the Useful God — for example, a phone number ending in 05, 50, 55, or 500 all carry Earth resonance.
The He Tu (河图) is a dot-pattern diagram associating numbers with the Five Elements and cardinal directions, used in BaZi and Saju for lucky-number derivation. The Lo Shu (洛書) is a 3x3 magic square (numbers 1-9, every line summing to 15) used in feng shui flying-star analysis and Qi Men Dun Jia. They are separate classical systems with different applications. BaZi lucky numbers come exclusively from the He Tu.
Without the birth hour, the Hour Pillar (the fourth pillar) is unknown, and up to two of the eight natal characters are missing. Useful God determination becomes less reliable because the elemental balance across all four pillars cannot be fully assessed. Practitioners can still produce a provisional reading from three pillars, but if you have any record of the approximate time of day — even "morning," "midday," or "evening" — narrowing to a two-hour Earthly Branch bracket significantly improves accuracy.
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