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Beralih ke Bahasa IndonesiaConvert any Gregorian date between 1901 and 2100 to the Chinese lunar calendar, with the 24 solar terms computed from the Sun's true position rather than looked up in a table, correct leap-month placement, all four 干支 pillars, and festivals resolved separately for mainland China, Hong Kong, Taiwan, Singapore, Malaysia and Vietnam. Where the 立春 and 正月初一 zodiac conventions disagree — which they do for anyone born between New Year and Chinese New Year — it shows both and names which is which instead of picking one silently.
Chinese Lunisolar Calendar
The 干支 year does not begin on 1 January. Depending on which tradition you follow it begins at 立春 or at 正月初一 — and those can fall either side of each other.
Each month, its first day, its new moon and the 中气 it holds. A month with no 中气 is the leap month only when it is the first such month in a 岁 (solstice to solstice) of thirteen months.
| Month | First day | Days | New moon | 中气 |
|---|
Solar terms computed from the Sun’s apparent longitude (truncated VSOP87 + nutation + aberration); new moons from Meeus ch. 49; leap months from the 无中气 rule. Checked against the Hong Kong Observatory’s 公曆與農曆對照表, 1901–2100: 2,473 of 2,474 month starts match on date, number and leap flag. The exception is the fourth month of 1906, which HKO starts on 24 April and this tool on 23 April. Also checked against HKO’s 二十四節氣 tables and the NAOJ ephemeris. Supported range 1901-01-01 to 2100-12-31.
How to use the 万年历
Pick a date
Any Gregorian date from 1 January 1901 to 31 December 2100. The wheel, the sheet and every reading below update together — they are all the same calculation.
Add the hour if you know it
The hour pillar needs one, and so does the 立春 boundary: 立春 has an instant, not just a date, so a birth two hours either side of it falls in a different 干支 year. Leave it blank and the tool leaves the hour pillar blank rather than assuming midnight.
Choose whose calendar
Mainland China, Hong Kong, Taiwan, Singapore, Malaysia or Vietnam. Vietnam computes its calendar at UTC+7, not UTC+8, so it genuinely lands on different days in some years — and the six-way comparison below shows you when.
Read the wheel
The 24 spokes sit at the Sun's true ecliptic longitude, 15° apart — that is what a 节气 is. 冬至 is at the bottom, 夏至 at the top. The cinnabar mark is where the Sun is on your date.
How a lunisolar calendar actually works
The Chinese calendar is routinely called a lunar calendar, and that is a misnomer. A true lunar calendar follows only the Moon — the Islamic calendar does, which is why its year runs about eleven days short and Ramadan walks backwards through the seasons. The Chinese calendar follows the Moon and the Sun at once, which is precisely why it is harder to compute than either.
The Moon sets the month, the Sun sets the year
A month begins at 朔 — the instant of conjunction, when the Sun and Moon share an ecliptic longitude. The day containing that instant is day one. Because the synodic period is about 29.53 days, months are 29 or 30 days long, and which is which follows no pattern: it has to be computed, month by month.
The Sun's contribution is the 24 solar terms. Each is the moment the Sun's apparent longitude reaches a multiple of 15° — 0° at the spring equinox, 90° at the summer solstice, 180° at the autumn equinox, 270° at the winter solstice. A 节气 is not a date; it is the arrival at an angle. That is why the wheel at the top of this page is a wheel: the angle you see is the longitude, drawn honestly.
The leap month is never scheduled
Twelve lunar months come to roughly 354 days; the tropical year is 365.24. Left alone, Chinese New Year would drift through the seasons the way Ramadan does. The repair is a leap month — but which month is not assigned by anyone. It falls out of the arithmetic.
Twelve of the 24 terms sit at multiples of 30° and are called 中气, major terms. The Sun takes about 30.4 days to cross 30°, while a lunar month lasts 29.53. Sooner or later a month arrives that contains no 中气 at all. In a 岁, the span from one winter solstice to the next, that holds thirteen months, the first such month is the leap month. It gets no name of its own; it repeats the number of the month before it, as 闰 that month. An empty month is not automatically the leap month: between 1901 and 2100 there are 77 months with no 中气 and 73 leap months. The other four, in 1985, 2033, 2034 and 2053, fall in a 岁 of twelve months or after that 岁's first empty month.
2033 is the famous trap. Its eighth month contains no 中气 and looks like a leap month — but the 岁 from the 2032 winter solstice to the 2033 one holds only twelve months, not thirteen, so there is no leap month there at all. The real one is 闰十一月, in December. Helmer Aslaksen's paper The Mathematics of the Chinese Calendar (a draft dated 2010) records that until the early 1990s all the Chinese calendars placed the leap month wrongly for that year.
A calendar has a meridian
Conjunctions and solstices are instants, and which DAY an instant falls on depends on the timezone you read it in. The Chinese calendar is now computed at the 120°E standard meridian, UTC+8. Aslaksen's paper dates that change to 1929; before it the calendar was computed on the Beijing meridian, 116°25′E, whose local mean time runs 14 minutes and 20 seconds behind. That is not pedantry: it is why Chinese New Year 1916 fell on 3 February rather than 4 February.
Vietnam runs the identical rules at UTC+7. North Vietnam moved to that clock for 1968, and this tool uses it for all of Vietnam from that year. Most years the two calendars agree; a few years they differ by a day; and in 1985 they differed by a month, because the December 1984 winter solstice fell on the 21st in Hanoi and the 22nd in Beijing, which changed which month counted as the eleventh and moved the entire year. Neither calendar is wrong. They are two correct calendars.
Why this tool gives three zodiac animals
There have always been two defensible answers to when the 干支 year turns. The 干支历 used for 八字 turns it at 立春, which has an instant. The 农历 year people mean in ordinary speech — "the year of the Horse" — turns at 正月初一, where the Hong Kong Observatory's table opens the year. The two can sit up to 16 days apart, in either order.
So for anyone born between 1 January and Chinese New Year, the animal genuinely depends on which convention you are using. Some free tools pick one silently, and some use 1 January, which has no traditional basis whatsoever. This tool shows all three, names which is which, and explains the disagreement when there is one. It is the same instinct behind this site's 姓名学 tool using Kangxi stroke counts rather than modern ones: surface the disagreement, rather than hiding it behind an arbitrary choice.
Ten things about the Chinese calendar
A 节气 is not a date but an angle: the instant the Sun reaches a multiple of 15° of ecliptic longitude. There are 24 of them because 360 ÷ 15 = 24.
The leap month is never scheduled. In a solstice-to-solstice 岁 that needs one, it is the first month containing no 中气, a gap that opens because a lunar month is shorter than the Sun's 30° step. Between 1901 and 2100, 77 months hold no 中气 and 73 are leap months.
The 8th month of 2033 has no 中气 but is not the leap month; the real one is 闰十一月. Helmer Aslaksen's paper The Mathematics of the Chinese Calendar records that all the Chinese calendars placed it wrongly until the early 1990s. The other empty months that are not leap fall in 1985, 2034 and 2053.
Until 1929 the Chinese calendar was computed at Beijing local mean time, 14 minutes 20 seconds behind the 120°E standard meridian used since. That gap moves a new moon across midnight often enough to matter.
Vietnam runs the same astronomy at UTC+7. In 1985 that put Tết on 21 January and 春节 on 20 February — a full month apart, not a day.
In the Vietnamese zodiac the rabbit is a cat (Mão / mèo). The buffalo for the ox is softer — Chinese 牛 is a generic bovine, so Vietnam narrows a broad word rather than swapping the animal.
Hong Kong's Mid-Autumn public holiday is the day after 中秋, not the festival itself.
除夕 is not a fixed lunar date. 腊月 runs 29 or 30 days depending on the moon, so New Year's Eve is 廿九 in some years and 三十 in others — 39 times and 62 times respectively between 1950 and 2050.
On 4 February 2038 立春 and 正月初一 fall on the same day — 正月初一 at 00:00, 立春 at 02:03. For about two hours the two zodiac conventions disagree inside a single date.
Of the 2,473 lunar months between 1901 and 2100, 52 begin on a new moon within a quarter-hour of midnight. On a clock an hour away those months start on a different date, and both dates are correct. New Year 2027 is one: 6 February at UTC+8, 7 February at UTC+9.
Frequently asked questions
- Because three conventions are genuinely in use and they disagree for anyone born between 1 January and Chinese New Year. The 干支历 used in 八字 turns the year at 立春; the 农历 year on the Hong Kong Observatory's table turns at 正月初一; and some free websites quietly use 1 January. We show all three and name which is which rather than picking one and hoping nobody notices.
- For the name of the 农历 year — what people mean by "the year of the Horse" in ordinary speech — 正月初一 is the official answer. For a 八字 chart, 立春 is the right boundary and always has been. They are two different year counters that happen to share names, not one counter with a disputed start. The 1 January reading has no traditional basis at all; it is listed only to explain why other sites disagree with this one.
- From the Sun's actual apparent longitude, using a truncated VSOP87 series with nutation and aberration applied, then converted from dynamical time to civil time via ΔT. There is no table of dates anywhere in the code. The results were checked against the Hong Kong Observatory's published 二十四節氣 tables and the NAOJ ephemeris, and agree to within a minute.
- Because that is exactly the span the Hong Kong Observatory publishes its conversion tables for, and outside it there is nothing authoritative to check the answers against. The astronomy would run happily for thousands of years; the confidence would not. Rather than return a plausible unchecked answer, the tool refuses.
- A lunar month begins on the day containing the new moon. When that new moon falls within a quarter-hour of midnight, the month starts on a different date on a clock an hour away, and the card tells you which way. New Year 2027 is the live example: 23:56 on 6 February at UTC+8 is 00:56 on the 7th at UTC+9, and Korea's astronomy institute lists the 7th. 52 of the 2,473 months in range are flagged. The flag does not mean the date is in doubt on its own clock. The two separate computations we compared differ by under 20 seconds to 2050, which shows the arithmetic agrees, not how far the future is known. The Hong Kong Observatory says uncertainty decades ahead may be up to a few minutes, and of the 23 flagged new moons still to come it names three as dates its table may get wrong by a day: 28 September 2057, 4 September 2089 and 7 August 2097. Only for those three does the tool say the date may move.
- Same rules, same astronomy, different meridian. North Vietnam moved to UTC+7 for 1968, and the tool uses UTC+7 for all of Vietnam from that year; China uses UTC+8. A new moon or a winter solstice falling in that one-hour window lands on a different civil day, and the calendars part company. Tết and 春节 differ in 1968, 1969, 2007, 2030 and 2053 by a day — and in 1985 by a whole month. One earlier gap comes from how the tool models the past: before 1968 it reads Vietnam at UTC+8, while China before 1929 is read at Beijing mean time, so Tết 1916 shows as 4 February against 春节 on 3 February. Helmer Aslaksen's paper says Vietnam traditionally used the longitude of Beijing, and we hold no Vietnamese record for that year, so treat 1916 as the model's output, not as history.
- No, and that is a deliberate line rather than an omission. It converts dates, computes solar terms, names 干支 and 生肖 and resolves festivals — all of which are arithmetic with checkable answers. It carries no 宜忌 column, rates no day, and predicts nothing. The engine's own test suite asserts the absence, so the boundary is enforced rather than merely intended.
- 周岁 is completed years since birth — the international reckoning. 虚岁 starts at 1 on the day of birth and gains a year at every 正月初一, not on the birthday. Someone born on 除夕 is 虚岁 2 the following day and 周岁 0. The tool shows both and the number of lunar new years counted, so the working is visible.
- Between 23:00 and 23:59 the 子 hour has begun but the calendar day has not turned. Under the 晚子时 rule the hour stem follows the next day's stem; under 早子时 it follows the current day's. Both are in use. The tool shows the 晚子时 reading and names the other rather than hiding the choice.
- No. Leave it blank and everything except the hour pillar is unaffected. The tool leaves the hour pillar empty rather than defaulting to midnight — an unknown hour is not 子时, and quietly assuming one is how wrong charts get built. The one other thing the hour changes is a birth within hours of 立春, where it decides the 干支 year.
Method & sources
How it computes
The Chinese lunisolar calendar for 1901–2100 is computed from astronomy rather than a lookup table: the 24 solar terms are the instants the Sun's apparent longitude reaches a multiple of 15° (VSOP87 with nutation and aberration), a month begins on the civil day of the true new moon, and a leap month is the first month in a 13-moon year with no major term (無中氣). Instants are read at UTC+8, Beijing mean time before 1929; Vietnam is the same computation at UTC+7 from 1968.
What this tool implements
- Rules: a month starts on the day of the true new moon; in a solstice-to-solstice span of 13 months the first with no 中氣 is the leap month; the year turns at 正月初一; all read at the 120°E (UTC+8) meridian, and on Beijing local mean time before 1929. Stated from Aslaksen and checked against the Hong Kong Observatory's table. GB/T 33661-2017 is the national standard for this calendar; its registry record was read and its text was not, so nothing here quotes it.
- Astronomy per Meeus, Astronomical Algorithms, 2nd ed.: solar longitude from a truncated Appendix III (VSOP87) series, nutation ch. 22, apparent position ch. 25, lunar phases ch. 49. ΔT follows the Espenak & Meeus polynomials, replaced by measured values for 2005–2025 and anchored at 2025 beyond them so no year jumps.
- Three zodiac-year conventions are reported side by side rather than one picked: 正月初一 (the official rule), 立春 (the 干支/八字 rule) and 1 January.
- Supported range 1901–2100 — the span of the Hong Kong Observatory's published conversion table; outside it the tool refuses rather than extrapolates.
- Calendar mathematics only: dates, terms, 干支 and 生肖, festivals. No 宜/忌, no auspiciousness, no compatibility.
Sources
- GB/T 33661-2017 农历的编算和颁行 (Calculation and promulgation of the Chinese calendar), issued 2017-05-12, in force 2017-09-01, competent department 中国科学院. Registry record only; the text was not read: https://openstd.samr.gov.cn/bzgk/std/newGbInfo?hcno=E107EA4DE9725…
- Meeus J. Astronomical Algorithms. 2nd ed. Richmond, VA: Willmann-Bell; 1998. ISBN 0-943396-61-1 — Appendix III (VSOP87), chapters 22, 25 and 49.
- Espenak F, Meeus J. Polynomial Expressions for Delta T (ΔT), NASA GSFC Eclipse Web Site: https://eclipse.gsfc.nasa.gov/SEcat5/deltatpoly.html
- Hong Kong Observatory, Gregorian–Lunar Calendar Conversion Table 1901–2100 (公曆與農曆日期對照表): https://www.hko.gov.hk/en/gts/time/conversion.htm — validation target: 2,473 of 2,474 month starts agree on date, number and leap flag; the exception is the fourth month of 1906 (HKO 24 April, computed 23 April). The same page names the new moons of 28 September 2057, 4 September 2089 and 7 August 2097 as ones its table may place a day out
- Hong Kong Observatory, Date and Time of the 24 Solar Terms: https://www.hko.gov.hk/en/gts/astronomy/Solar_Term.htm — published term times 2019–2028 agree to within one minute
- 国立天文台 暦計算室 (National Astronomical Observatory of Japan, Calendar Office), 二十四節気 ephemeris: https://eco.mtk.nao.ac.jp/koyomi/ — independent check at UTC+8 for 1984, 2000 and 2050
- 中央研究院 兩千年中西曆轉換 (Academia Sinica Sinocal): https://sinocal.sinica.edu.tw/ — independent corroboration of all 200 Chinese New Years, including the 1901–1928 Beijing-local-mean-time era
- Aslaksen H. The Mathematics of the Chinese Calendar. Draft dated 17 July 2010. Cited by title: the meridian history, the leap month of 2033 and North Vietnam's 1968 change.
What can make this go out of date
- ΔT is measured only through 2025; later years use an anchored extrapolation, so term times decades ahead can shift by a minute or two as observations accumulate.
- The Hong Kong Observatory publishes each year's solar-term times annually; the checked set runs 2019–2028.
Abridged — the full review record for this tool runs longer than the list above.
Pick up where you left off
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