[{"data":1,"prerenderedAt":278},["ShallowReactive",2],{"article:twelve-year-cycle-jupiter:en":3,"article-topic:chinese-zodiac:en":159,"related-articles:en:chinese-zodiac:twelve-year-cycle-jupiter:bazi-four-pillars":237},{"slug":4,"title":5,"description":6,"category":7,"topicSlug":8,"legacyPath":9,"authorId":10,"publishedAt":11,"updatedAt":12,"noindex":13,"summary":14,"sections":15,"references":122,"relatedTools":138,"seo":140,"contentImage":145},"twelve-year-cycle-jupiter","Why Twelve Animals: Twenty-Eight Mansions Divided by Twelve","The twelve animals sit on a twelve-step count of Jupiter's circuit through twenty-eight mansions. Twenty-eight does not divide evenly by twelve, and the rounding rule that fixes it explains the cycle.","Zodiac","chinese-zodiac","","chen-jun","2026-10-26","2026-10-31",false,"The Huainanzi states the cycle as Jupiter crossing twenty-eight mansions in twelve years, three mansions in some years and two in others. The split is a rounding rule: 28 ÷ 12 is 2.33, and the annual average it produces sits 0.35° away from the planet's actual advance.",[16,21,49,74,79,85,92,113],{"heading":17,"body":18},"The twelve-step count is older than the animals",[19,20],"The sequence — rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog, pig — is the part everyone knows and the least informative part. What the cycle actually is, is a twelve-step count of years. The steps are named after animals because twelve arbitrary numbers are hard to hold in the head and twelve animals are not. The animal is a mnemonic attached to a number, and the number came first.","So the real question is not what each animal means. It is why the count has twelve steps and not ten or fourteen. The Huainanzi answers it in one sentence, and the sentence is a division problem.",{"heading":22,"body":23,"table":26},"The Huainanzi sentence is a division problem",[24,25],"The passage reads: 太陰在四仲，則歲星行三宿；太陰在四鉤，則歲星行二宿。二八十六，三四十二，故十二歲而行二十八宿。 Jupiter — 歲星, the year star — travels through the twenty-eight lunar mansions, three mansions in some years and two in others, and closes the circuit in twelve years.","The arithmetic in the middle is the part usually skipped. 二八十六 is eight positions at two mansions each; 三四十二 is four positions at three each. Twelve positions, twenty-eight mansions, twelve years. Laid out:",{"headers":27,"rows":32},[28,29,30,31],"Group","Positions","Mansions a year","Subtotal",[33,38,42,44],[34,35,36,37],"四仲 — 子 午 卯 酉","4","3","12",[39,35,40,41],"四鉤 — 寅 申 巳 亥","2","8",[43,35,40,41],"四維 — 辰 戌 丑 未",[45,46,47,48],"Total","12 years","—","28 mansions",{"heading":50,"body":51,"table":54},"The division does not come out even, which is why the split exists",[52,53],"Twenty-eight mansions spread over twelve years is 2.33 mansions a year, and 2.33 is not a whole number. A planet cannot spend two thirds of a year in one mansion and move on, because the mansion is a label for a region, not a duration. The only way to keep the count integral is to give some years three and the rest two — which is exactly what the passage does, and why it needs two separate clauses to say it.","The cost of that repair shows up the moment the units are converted. If the twenty-eight mansions are treated as an even division of the circle, each is 360 ÷ 28 = 12.86°. Two and a third of those is 30.0° a year. NASA puts Jupiter's sidereal period at 11.86 years, which is 30.35° a year. The count and the planet part company by 0.35° a year:",{"headers":55,"rows":58},[56,57],"Quantity","Value",[59,62,65,68,71],[60,61],"28 mansions ÷ 12 years","2.33 mansions a year",[63,64],"One mansion, if the circle is split evenly (360° ÷ 28)","12.86°",[66,67],"2.33 × 12.86°","30.0° a year",[69,70],"Jupiter's actual advance (NASA, 11.86-year orbit)","30.35° a year",[72,73],"Difference","0.35° a year",{"heading":75,"body":76},"Counted in mansions instead of degrees, the gap is a third of a mansion",[77,78],"The same shortfall can be stated without degrees at all, which is closer to how the original count was kept. Twelve years of Jupiter at 30.35° a year is 364.2°, and 364.2° ÷ 12.86° is 28.3 mansions. The count says twenty-eight. The planet delivers twenty-eight and a third.","So the residue is not only a number of degrees. It is a fraction of a mansion per cycle, which is precisely the quantity the passage had to round away in order to keep the year count integral. The rounding and the drift are the same fact described twice.",{"heading":80,"body":81},"Dividing the circle evenly removes the ambiguity",[82,83,84],"The alternative needs no allocation at all. Split 360° into twelve equal parts and every part is 30°, every year, with nothing left over and nothing to distribute. There is no year that has to absorb a fraction, and no dependence on which mansion happens to be where.","That is the whole advantage, and it is a bookkeeping advantage rather than an astronomical one. A cycle built from equal parts can be computed forward from any starting point without consulting the sky. A cycle built from mansion counts cannot, because the mansions are landmarks of unequal width and the count is only defined relative to them.","The trade is real in both directions. An even division buys arithmetic that always closes, and gives up any claim to describe where the planet actually is. A mansion count keeps a visible link to the sky, and cannot be added up without a rounding rule.",{"heading":86,"body":87},"Why an approximate count was good enough to keep",[88,89,90,91],"A year count has two possible jobs. One is to say where Jupiter is; the other is to give each year a label that never repeats ambiguously. The first job needs the planet. The second needs only internal consistency.","Once the count was doing the second job, the 0.35° stopped mattering. Nobody numbering a year needs the number to be a position; they need last year's number to differ from this year's by exactly one. The twelve-step ring delivers that, and delivers it without an observation, which is why it outlasted the observation it was built from.","The residue only becomes a problem when someone tries to run the count backwards — to take a year label and infer a sky position from it. That inference is where the accumulated error turns into a visible mismatch, and it is the reason the label system was eventually separated from the planet altogether.","Once separated, the twelve-step ring became reusable. The same twelve labels were hung on the months, with the 寅 month beginning at 立春; on the double-hours; and on the years. The animal names arrived later and were attached to the branches, and the branches were never Jupiter.",{"heading":93,"body":94,"table":97},"Twelve branches under ten stems",[95,96],"A bare twelve-year animal cycle repeats every twelve years, which is too short to date anything. The count that is actually used pairs the twelve branches with ten stems, and the pair repeats every sixty years, because sixty is the least common multiple of ten and twelve. The animal repeats; the full label does not.","Three rat years, twelve years apart, share the branch and nothing else. The stem is what separates them, and the stem is the half a chart reads.",{"headers":98,"rows":102},[99,100,101],"Year","Year pillar","Animal",[103,107,110],[104,105,106],"2020","庚子","rat",[108,109,106],"2032","壬子",[111,112,106],"2044","甲子",{"heading":114,"body":115,"bullets":116},"What the animal therefore does and does not tell you","Five consequences follow from the construction:",[117,118,119,120,121],"It gives a position in a twelve-count. Two people born twelve years apart share it, and so does roughly one in twelve of everyone alive.","It dates nothing on its own. The stem is missing, and the stem is the half that distinguishes one rat year from another.","It does not describe a temperament. The animal names a station in a count built to track a planet; no step in that construction measures a person.","It is a rounded number. Twelve years is where the count lands, not where Jupiter lands, and the gap is 0.35° a year rather than zero.","It is not even one count. The year it belongs to starts at 立春 for chart work and at the lunar new year for folk reckoning, and those dates sit up to a fortnight apart.",[123,130],{"id":124,"kind":125,"title":126,"detail":127,"publisher":128,"url":129,"accessedAt":11},"huainanziTianwenxun","traditional","Huainanzi, “Treatise on Celestial Patterns” (淮南子·天文訓)","The Han text that states the twelve-year count as an observation of Jupiter: 太陰在四仲，則歲星行三宿；太陰在四鉤，則歲星行二宿。二八十六，三四十二，故十二歲而行二十八宿。 It then fixes the schematic counter that replaces the planet — 天維建元，常以寅始起，右徙一歲而移，十二歲而大周天 — and names the clash as the opposite point: 歲星之所居，五榖豐昌，其對爲衝。 Cited for the period and the vocabulary only; nothing in it predicts anything about a person.","Wikisource digital text","https:\u002F\u002Fzh.wikisource.org\u002Fwiki\u002F%E6%B7%AE%E5%8D%97%E5%AD%90\u002F%E5%A4%A9%E6%96%87%E8%A8%93",{"id":131,"kind":132,"title":133,"detail":134,"publisher":135,"url":136,"accessedAt":137},"nasaJupiter","practical","NASA Science: Jupiter Facts","The orbital figure behind the tai sui explanation: NASA gives Jupiter one orbit in about 4,333 Earth days, which is 11.86 years rather than the twelve the schematic cycle assumes. Cited for the period only; nothing in the source supports a claim about fortune.","NASA Science","https:\u002F\u002Fscience.nasa.gov\u002Fjupiter\u002Fjupiter-facts\u002F","2026-10-19",[139],"bazi-four-pillars",{"title":141,"description":142,"path":143,"type":144},"Why Twelve Animals: 28 Mansions Divided by 12","Twenty-eight mansions over twelve years is 2.33 a year, so the count has to round. Here is the rounding rule in the Huainanzi and what it costs in degrees.","\u002Farticles\u002Ftwelve-year-cycle-jupiter","article",{"src":146,"srcByLocale":147,"alt":149,"width":150,"height":151,"altByLocale":152,"captionByLocale":155},"\u002Fimg\u002Farticles\u002Ftwelve-year-cycle-jupiter.svg",{"tw":148},"\u002Fimg\u002Farticles\u002Ftwelve-year-cycle-jupiter-tw.svg","Two-column diagram of the rounding rule in the Huainanzi: four years at three mansions and eight years at two, totalling twenty-eight mansions over twelve years, an annual average of 30 degrees against Jupiter’s 30.35.",1280,960,{"zh":153,"tw":154},"两栏对照：四仲四年各走三宿，四钩与四维八年各走两宿，十二年合计二十八宿；末行给出年均 30 度与木星实际 30.35 度的差距。","兩欄對照：四仲四年各走三宿，四鉤與四維八年各走兩宿，十二年合計二十八宿；末行給出年均 30 度與木星實際 30.35 度的差距。",{"en":156,"zh":157,"tw":158},"The rule in the Huainanzi is a rounding decision: twenty-eight does not divide by twelve, so four years take three mansions and eight take two. The average comes to 30 degrees a year, against the planet’s 30.35.","《淮南子》那条规则是一次取整决定：二十八不能被十二整除，所以四年各走三宿、八年各走两宿。平均下来每年 30 度，而行星实际走 30.35 度。","《淮南子》那條規則是一次取整決定：二十八不能被十二整除，所以四年各走三宿、八年各走兩宿。平均下來每年 30 度，而行星實際走 30.35 度。",{"topic":160,"articles":193,"tools":231},{"slug":8,"title":161,"eyebrow":162,"description":163,"relatedTools":164,"articleIdeas":165,"seo":170,"sections":174},"Chinese Zodiac","Twelve branches, four animals","The animal is a branch label, and a chart carries four of them. Where the twelve-year count came from, what the year boundary does to it, what the compatibility pairs and fan tai sui actually count, and which of the four animals a reading turns on.",[139],[166,167,168,169],"Why There Are Twelve Animals","What Fan Tai Sui Counts","Four Animals in One Chart","The 23:00 Day Boundary",{"title":171,"description":172,"path":173},"Chinese Zodiac: Twelve Branches, Four Animals","Where the twelve-year animal count came from, what the year boundary does to it, what fan tai sui and the compatibility pairs actually count, and which animal a reading turns on.","\u002Ftopics\u002Fchinese-zodiac",[175,178,181,184,187,190],{"heading":176,"body":177},"What the animal is, before it is a personality","生肖 names one of the twelve earthly branches. A birth chart has four pillars and every pillar carries a branch, so a chart carries four animals rather than one — and two of the four are often the same. The animal most people quote is the year branch, and it is quoted because it changes once every twelve years, which makes it the easiest of the four to remember and the least informative of the four to read. Everything else in this topic follows from that: the animal is a position in a count, and the count has a history, a boundary problem, and a set of relations that are exact arithmetic rather than prediction.",{"heading":179,"body":180},"Where the twelve come from","The count is older than the animals. In the Huainanzi the cycle is stated as an observation of Jupiter: the year star moves through the twenty-eight lunar mansions, three in some years and two in others, and closes the circuit in twelve. Jupiter actually takes 11.86 years, so a count tied to its observed position gains about 51 days every cycle and drifts a full station in roughly eighty years. The same chapter supplies the repair — a point that starts at 寅, shifts one station per year in the opposite direction, and completes the circuit in twelve years by definition. That point is 太歲, and because it is defined rather than measured it cannot drift. The animal names were attached to the branches afterwards, and the branches were never Jupiter.",{"heading":182,"body":183},"The boundary problem nobody mentions","A year animal needs a year, and there are two candidates. Chart work changes the year at 立春, the solar term that falls around 4 February. Folk reckoning changes it at the lunar new year, which falls between 21 January and 20 February. In most years the two dates are a week or two apart, and anyone born in that gap has two defensible year animals. This is not a modern confusion: the solar-term year is what the four pillars are built from, and the lunar year is what a calendar prints. Both are correct inside their own convention, and a page that gives one without saying which is not answering the question.",{"heading":185,"body":186},"What people actually ask: compatibility and fan tai sui","Two questions bring almost everyone to this topic. The first is whether two animals go together. The branch relations behind that answer are fixed: 沖 is six stations apart, 合 is a defined pairing, and 刑 and 害 are defined sets, so twelve animals give sixty-six pairs and every pair has an answer. What the answer is worth is a separate matter, and it is settled by counting: a relation between two branches is a statement about two positions, not about two people. The second question is fan tai sui, being told at each new year that you offend the year. That phrase bundles five relations — 值, 沖, 刑, 害, 破 — and their union covers four or five of the twelve branches in any given year. A label that applies to a third of everyone every year cannot pick anyone out of that third. The daily almanac uses the identical twelve branches one level down, where each animal gets thirty-odd clash days a year whatever the year animal is.",{"heading":188,"body":189},"What the animal can and cannot tell you","It tells you a position. Two people born twelve years apart share the year animal, and so does roughly one in twelve of everyone alive, which is the arithmetic that limits what the label can carry. It does not describe a temperament: nothing in a count built to track a planet measures a person. It does not date anything on its own either, because the animal is only the branch half of a sixty-year label and the stem is the half that separates one rat year from another. What a reading actually turns on is the day branch, because the day stem is the Day Master and every other judgement is made relative to it — and the day branch is the one part of a chart that cannot be estimated from a date.",{"heading":191,"body":192},"Where to start, and with what","The four articles in this topic take the four questions in order: why there are twelve, what fan tai sui counts, which of the four animals is being read, and what happens to the day pillar when a birth falls between 23:00 and midnight. The Four Pillars calculator is the live tool that produces all four pillars with their branches, hidden stems and element distribution, so it is the one place to see the four animals of a chart at once rather than guessing the year animal from a birth year. For the day level — which day clashes with which branch — the date-selection tool answers a question that actually varies from day to day.",[194,197,208,220],{"slug":4,"title":5,"description":6,"category":7,"topicSlug":8,"legacyPath":9,"authorId":10,"publishedAt":11,"updatedAt":12,"summary":14,"relatedTools":195,"seo":196},[139],{"title":141,"description":142,"path":143,"type":144},{"slug":198,"title":199,"description":200,"category":7,"topicSlug":8,"legacyPath":9,"authorId":10,"publishedAt":11,"updatedAt":201,"summary":202,"relatedTools":203,"seo":204},"tai-sui-and-fan-tai-sui","Fan Tai Sui: Jupiter's Shortfall and the Count Behind It","Tai sui is a bookkeeping point, invented because Jupiter takes 11.862 years, not 12. The five branch relations implicate four or five of twelve every year, and all twelve within a cycle.","2026-10-30","Jupiter gains 0.35° a year on the twelve-part count, so after about 86 years it is a whole station ahead — which is why the year point is fictitious rather than observed. The five relations cover 4.33 of twelve branches on average, and 值 plus 沖 alone catch every person twice in any twelve years.",[139],{"title":205,"description":206,"path":207,"type":144},"Fan Tai Sui: Jupiter's Shortfall and the Count","Tai sui is a position in a twelve-station count, not a planet: Jupiter runs 4.2 degrees short every twelve years. The five relations touch four or five branches, and all twelve within a cycle.","\u002Farticles\u002Ftai-sui-and-fan-tai-sui",{"slug":209,"title":210,"description":211,"category":7,"topicSlug":8,"legacyPath":9,"authorId":212,"publishedAt":11,"updatedAt":213,"summary":214,"relatedTools":215,"seo":216},"four-animals-in-one-chart","Four Animals in One Chart, and What the Count Says","A chart carries four animals, not one. 20,736 four-animal combinations, 42.7% of charts repeating one, and six readable pairs: the arithmetic behind the set.","sun-hao","2026-11-01","Four animals at four change rates. 12^4 = 20,736 combinations put about 395,000 people in each bucket, and adding the stems multiplies the resolution twenty-five-fold. 42.7% of charts repeat an animal, and four branches give six pairs to read.",[139],{"title":217,"description":218,"path":219,"type":144},"Four Animals in One Chart: Resolution, Repeats, Pairs","Four animals, four change rates. How many people share your combination, why 42.7% of charts repeat one, and where the six readable pairs come from.","\u002Farticles\u002Ffour-animals-in-one-chart",{"slug":221,"title":222,"description":223,"category":224,"topicSlug":8,"legacyPath":9,"authorId":212,"publishedAt":11,"updatedAt":201,"summary":225,"relatedTools":226,"seo":227},"late-zi-hour-day-boundary","The 23:00 Boundary: Two Pillars Change, Not One","The 子 hour runs 23:00–01:00, so midnight sits inside it. One convention turns the day at 23:00, the other at midnight — and since the hour stem follows the day stem, both pillars change.","BaZi","On 5 December 2026 the day pillar steps from 癸丑 to 甲寅 at 23:00 and the hour from 癸亥 to 甲子, while the lunar date waits for midnight. Across China the same 23:00 clock minute is 亥 in Beijing, 子 in Shanghai and 戌 in Ürümqi.",[139],{"title":228,"description":229,"path":230,"type":144},"The 23:00 Day Boundary in BaZi: Two Pillars, Not One","子時 spans 23:00 to 01:00, so midnight sits inside it. Two conventions, two day pillars, and because the hour stem follows the day stem, two hour pillars as well.","\u002Farticles\u002Flate-zi-hour-day-boundary",[232],{"slug":139,"title":233,"shortTitle":234,"description":235,"category":224,"status":236},"Four Pillars BaZi Calculator","Four Pillars","Enter a Gregorian birth date and local time to see the four pillars, hidden stems, Ten Gods, Na Yin, branch relations, and element counts, with clear calendar and time-boundary limits.","live",{"articles":238},[239,253,268],{"slug":240,"title":241,"description":242,"category":224,"topicSlug":243,"legacyPath":244,"authorId":10,"publishedAt":245,"updatedAt":246,"summary":247,"relatedTools":248,"seo":250},"bazi-five-elements-lookup","BaZi Five Elements Lookup","A practical introduction to the five elements in BaZi and how Wood, Fire, Earth, Metal, and Water are used in birth profile interpretation.","bazi","\u002Fpages\u002Farticles\u002Fbazi-wuxing-chaxun.html","2025-09-01","2026-07-14","The five elements are one of the easiest ways to begin reading BaZi. Learn what each element represents and why balance matters more than a simple good-or-bad label.",[249,139],"bazi-marriage",{"title":241,"description":251,"path":252,"type":144},"Learn how the five elements are used in BaZi birth profile interpretation and relationship compatibility reports.","\u002Farticles\u002Fbazi-five-elements-lookup",{"slug":254,"title":255,"description":256,"category":257,"topicSlug":258,"legacyPath":259,"authorId":260,"publishedAt":261,"updatedAt":262,"summary":263,"relatedTools":264,"seo":266},"moving-day-auspicious-date","Auspicious Moving Day Selection","A practical guide to choosing an auspicious moving day with traditional date selection and modern moving logistics.","Date Selection","feng-shui-cures","\u002Fpages\u002Farticles\u002Fbanjia-ze-jiri.html","zhang-hao","2025-09-19","2026-10-15","Moving day selection works best when traditional timing supports real preparation, safety, cleaning, utilities, and a calm first entry.",[139,265],"qi-men-dun-jia",{"title":255,"description":256,"path":267},"\u002Farticles\u002Fmoving-day-auspicious-date",{"slug":269,"title":270,"description":271,"category":224,"topicSlug":243,"legacyPath":272,"authorId":10,"publishedAt":273,"updatedAt":246,"summary":274,"relatedTools":275,"seo":276},"is-bazi-fortune-telling-accurate","Is BaZi Fortune Telling Accurate?","Examine how birth-data quality, chart rules, school differences, and the Barnum effect shape the perceived accuracy of a BaZi reading.","\u002Fpages\u002Farticles\u002Fbazi-suanming-zhun-ma.html","2025-09-21","Chart calculation and interpretation are two different things, and two methods can disagree on the same chart. The limits that follow cover health, finance, law, and relationship decisions.",[139],{"title":270,"description":271,"path":277},"\u002Farticles\u002Fis-bazi-fortune-telling-accurate",1793614153162]