# Sexagenary cycle

Sexagenary cycle
Chinese六十干支
Stems-and-Branches
Chinese干支

The sexagenary cycle, also known as the Stems-and-Branches or ganzhi, is a cycle of sixty terms, each corresponding to one year, thus a total of sixty years for one cycle, used for reckoning time in China and the rest of the East Asian cultural sphere.[1] It appears as a means of recording days in the first Chinese written texts, the Shang oracle bones of the late second millennium BC. Its use to record years began around the middle of the 3rd century BC.[2] The cycle and its variations have been an important part of the traditional calendrical systems in Chinese-influenced Asian states and territories, particularly those of Japan, Korea, and Vietnam, with the old Chinese system still in use in Taiwan.

This traditional method of numbering days and years no longer has any significant role in modern Chinese time-keeping or the official calendar. However, the sexagenary cycle is used in the names of many historical events, such as the Chinese Xinhai Revolution, the Japanese Boshin War, and the Korean Imjin War. It also continues to have a role in contemporary Chinese astrology and fortune telling.

## Overview

Statues of Tai Sui deities responsible for individual years of the sexagenary cycle

Each term in the sexagenary cycle consists of two Chinese characters, the first being one of the ten Heavenly Stems of the Shang-era week and the second being one of the twelve Earthly Branches representing the years of Jupiter's duodecennial orbital cycle. The first term jiǎzǐ (甲子) combines the first heavenly stem with the first earthly branch. The second term yǐchǒu (乙丑) combines the second stem with the second branch. This pattern continues until both cycles conclude simultaneously with guǐhài (癸亥), after which it begins again at jiǎzǐ. This termination at ten and twelve's least common multiple leaves half of the combinations—such as jiǎchǒu (甲丑)—unused; this is traditionally explained by reference to pairing the stems and branches according to their yin and yang properties.

This combination of two sub-cycles to generate a larger cycle and its use to record time have parallels in other calendrical systems, notably the Akan calendar.[3]

## History

The sexagenary cycle is attested as a method of recording days from the earliest written records in China, records of divination on oracle bones, beginning ca. 1250 BC. Almost every oracle bone inscription includes a date in this format. This use of the cycle for days is attested throughout the Zhou dynasty and remained common into the Han period for all documentary purposes that required dates specified to the day.

Almost all the dates in the Spring and Autumn Annals, a chronological list of events from 722 to 481 BC, use this system in combination with regnal years and months (lunations) to record dates. Eclipses recorded in the Annals demonstrate that continuity in the sexagenary day-count was unbroken from that period onwards. It is likely that this unbroken continuity went back still further to the first appearance of the sexagenary cycle during the Shang period.[4]

The use of the sexagenary cycle for recording years is much more recent. The earliest discovered documents showing this usage are among the silk manuscripts recovered from Mawangdui tomb 3, sealed in 168 BC. In one of these documents, a sexagenary grid diagram is annotated in three places to mark notable events. For example, the first year of the reign of Qin Shi Huang (秦始皇), 246 BC, is noted on the diagram next to the position of the 60-cycle term yǐ-mǎo (乙卯, 52 of 60), corresponding to that year.[5] [6] Use of the cycle to record years became widespread for administrative time-keeping during the Western Han dynasty (202 BC – 8 AD). The count of years has continued uninterrupted ever since:[7] the year 1984 began the present cycle (a 甲子jiǎ-zǐ year), and 2044 will begin another. Note that in China the new year, when the sexagenary count increments, is not January 1, but rather the lunar new year of the traditional Chinese calendar. For example, the ji-chou 己丑 year (coinciding roughly with 2009) began on January 26, 2009. (However, for astrology, the year begins with the first solar term "Lìchūn" (立春), which occurs near February 4.)

In Japan, according to Nihon shoki, the calendar was transmitted to Japan in 553. But it was not until the Suiko era that the calendar was used for politics. The year 604, when the Japanese officially adopted the Chinese calendar, was the first year of the cycle.[8]

The Korean (환갑; 還甲 hwangap) and Japanese tradition (還暦 kanreki) of celebrating the 60th birthday (literally 'return of calendar') reflects the influence of the sexagenary cycle as a count of years.[9]

The Tibetan calendar also counts years using a 60-year cycle based on 12 animals and 5 elements, but while the first year of the Chinese cycle is always the year of the Wood Rat, the first year of the Tibetan cycle is the year of the Fire Rabbit (丁卯dīng-mǎo, year 4 on the Chinese cycle).[10]

## Ten Heavenly Stems

No. Heavenly
Stem
Chinese
name
Japanese
name
Korean
name
Vietnamese
name
Yin Yang Wu Xing
Mandarin
(Pinyin)
Cantonese
(Lau)
Onyomi Kunyomi with
corresponding kanji
Romanized Hangul
1 jiǎ gaap3 kō (こう) kinoe (木の兄) gap giáp yang wood
2 yuet3 otsu (おつ) kinoto (木の弟) eul ất yin
3 bǐng bing2 hei (へい) hinoe (火の兄) byeong bính yang fire
4 dīng ding1 tei (てい) hinoto (火の弟) jeong đinh yin
5 mo6 bo () tsuchinoe (土の兄) mu mậu yang earth
6 gei2 ki () tsuchinoto (土の弟) gi kỷ yin
7 gēng gang1 kō (こう) kanoe (金の兄) gyeong canh yang metal
8 xīn san1 shin (しん) kanoto (金の弟) shin tân yin
9 rén yam4 jin (じん) mizunoe (水の兄) im nhâm yang water
10 guǐ gwai3 ki () mizunoto (水の弟) gye quý yin

## Twelve Earthly Branches

No. Earthly
Branch
Chinese
name
Japanese
name
Korean
name
Vietnamese
name
Vietnamese
zodiac
Chinese
zodiac
Corresponding
hours
Mandarin
(pinyin)
Cantonese
(Lau)
Onyomi Kunyomi Romanized Hangul
1 ji2 shi ne ja Rat (chuột;𤝞) Rat () 11 p.m. to 1 a.m.
2 chǒu chau2 chū ushi chuk sửu Water buffalo (trâu;𤛠) Ox () 1 to 3 a.m.
3 yín yan4 in tora in dần Tiger (hổ/cọp;虎/𧲫) Tiger () 3 to 5 a.m.
4 mǎo maau5 u myo mão/mẹo Cat (mèo;猫) Rabbit () 5 to 7 a.m.
5 chén san4 shin tatsu jin thìn Dragon (rồng;龍) Dragon () 7 to 9 a.m.
6 ji6 shi mi sa tỵ Snake (rắn;𧋻) Snake () 9 to 11 a.m.
7 ng5 go uma o ngọ Horse (ngựa;馭) Horse () 11 a.m. to 1 p.m.
8 wèi mei6 mi or bi hitsuji mi mùi Goat (dê;羝) Goat () 1 to 3 p.m.
9 shēn san1 shin saru shin thân Monkey (khỉ;𤠳) Monkey () 3 to 5 p.m.
10 yǒu jau5 tori yu dậu Rooster (gà;𪂮) Rooster () 5 to 7 p.m.
11 sut1 jutsu inu sul tuất Dog (chó;㹥) Dog () 7 to 9 p.m.
12 hài hoi6 gai i hae hợi Pig (lợn/heo;𤞼/㺧) Pig () 9 to 11 p.m.

*The names of several animals can be translated into English in several different ways. The Vietnamese Earthly Branches use cat instead of Rabbit.

## Conversion between cyclic years and Western years

Relationship between sexagenary cycle and recent Common Era years

As mentioned above, the cycle first started to be used for indicating years during the Han dynasty, but it also can be used to indicate earlier years retroactively. Since it repeats, by itself it cannot specify a year without some other information, but it is frequently used with the Chinese era name (年号; "niánhào") to specify a year.[11] The year starts with the new year of whoever is using the calendar. In China, the cyclic year normally changes on the Chinese Lunar New Year. In Japan until recently it was the Japanese lunar new year, which was sometimes different from the Chinese; now it is January 1. So when calculating the cyclic year of a date in the Gregorian year, one have to consider what their "new year" is. Hence, the following calculation deals with the Chinese dates after the Lunar New Year in that Gregorian year; to find the corresponding sexagenary year in the dates before the Lunar New Year would require the Gregorian year to be decreased by 1.

As for example, the year 2697 BC (or -2696, using the astronomical year count), traditionally the first year of the reign of the legendary Yellow Emperor, was the first year (甲子; jiǎ-zǐ) of a cycle. 2700 years later in 4 AD, the duration equivalent to 45 60-year cycles, was also the starting year of a 60-year cycle. Similarly 1980 years later, 1984 was the start of a new cycle.

Thus, to find out the Gregorian year's equivalent in the sexagenary cycle use the appropriate method below.

1. For any year number greater than 4 AD, the equivalent sexagenary year can be found by subtracting 3 from the Gregorian year, dividing by 60 and taking the remainder. See example below.
2. For any year before 1 AD, the equivalent sexagenary year can be found by adding 2 to the Gregorian year number (in BC), dividing it by 60, and subtracting the remainder from 60.
3. 1 AD, 2 AD and 3 AD correspond respectively to the 58th, 59th and 60th years of the sexagenary cycle.
4. The formula for years AD is (year - 3 or + 57) mod 60 and for years BC is 60 - (year + 2) mod 60.

The result will produce a number between 0 and 59, corresponding to the year order in the cycle; if the remainder is 0, it corresponds to the 60th year of a cycle. Thus, using the first method, the equivalent sexagenary year for 2012 AD is the 29th year (壬辰; rén-chén), as (2012-3) mod 60 = 29 (i.e., the remainder of (2012-3) divided by 60 is 29). Using the second, the equivalent sexagenary year for 221 BC is the 17th year (庚辰; gēng-chén), as 60- [(221+2) mod 60] = 17 (i.e., 60 minus the remainder of (221+2) divided by 60 is 17).

### Examples

Step-by-step example to determine the sign for 1967:

1. 1967 – 3 = 1964 ("subtracting 3 from the Gregorian year")
2. 1964 ÷ 60 = 32 ("divide by 60 and discard any fraction")
3. 1964 – (60 × 32) = 44 ("taking the remainder")
4. Show one of the Sexagenary Cycle tables (the following section), look for 44 in the first column (No) and obtain Fire Goat (丁未; dīng-wèi).

Step-by-step example to determine the cyclic year of first year of the reign of Qin Shi Huang (246 BC):

1. 246 + 2 = 248 ("adding 2 to the Gregorian year number (in BC)")
2. 248 ÷ 60 = 4 ("divide by 60 and discard any fraction")
3. 248 – (60 × 4) = 8 ("taking the remainder")
4. 60 – 8 = 52 ("subtract the remainder from 60")
5. Show one of the Sexagenary Cycle table (the following section), look for 52 in the first column (No) and obtain Wood Rabbit (乙卯; yǐ-mǎo).

### A shorter equivalent method

Start from the AD year, take directly the remainder mod 60, and look into column AD:

• 1967 = 60 × 32 + 47. Remainder is therefore 47 and the AD column of the table "Sexagenary years" (just above) gives 'Fire Goat'

For a BC year: discard the minus sign, take the remainder of the year mod 60 and look into column BC:

• 246 = 60 × 4 + 6. Remainder is therefore 6 and the BC column of table "Sexagenary years" (just above) gives 'Wood Rabbit'.

When doing these conversions, year 246 BC cannot be treated as -246 AD due to the lack of a year 0 in the Gregorian AD/BC system.

The following tables show recent years (in the Gregorian calendar) and their corresponding years in the cycles:

## Sexagenary months

The branches are used marginally to indicate months. Despite there being twelve branches and twelve months in a year, the earliest use of branches to indicate a twelve-fold division of a year was in the 2nd century BC. They were coordinated with the orientations of the Great Dipper, (建子月: jiànzǐyuè, 建丑月: jiànchǒuyuè, etc.).[12] [13] There are two systems of placing these months, the lunar one and the solar one.

One system follows the ordinary Chinese lunar calendar and connects the names of the months directly to the central solar term (中氣; zhōngqì). The jiànzǐyuè (()子月) is the month containing the winter solstice (i.e. the 冬至 Dōngzhì) zhōngqì. The jiànchǒuyuè (()丑月) is the month of the following zhōngqì, which is Dàhán (大寒), while the jiànyínyuè (()寅月) is that of the Yǔshuǐ (雨水) zhōngqì, etc. Intercalary months have the same branch as the preceding month. [14] In the other system (節月; jiéyuè) the "month" lasts for the period of two solar terms (two 氣策 qìcì). The zǐyuè (子月) is the period starting with Dàxuě (大雪), i.e. the solar term before the winter solstice. The chǒuyuè (丑月) starts with Xiǎohán (小寒), the term before Dàhán (大寒), while the yínyuè (寅月) starts with Lìchūn (立春), the term before Yǔshuǐ (雨水), etc. Thus in the solar system a month starts anywhere from about 15 days before to 15 days after its lunar counterpart.

The branch names are not usual month names; the main use of the branches for months is astrological. However, the names are sometimes used to indicate historically which (lunar) month was the first month of the year in ancient times. For example, since the Han dynasty, the first month has been jiànyínyuè, but earlier the first month was jiànzǐyuè (during the Zhou dynasty) or jiànchǒuyuè (traditionally during the Shang dynasty) as well.[15]

For astrological purposes stems are also necessary, and the months are named using the sexagenary cycle following a five-year cycle starting in a jiǎ (; 1st) or (; 6th) year. The first month of the jiǎ or year is a bǐng-yín (丙寅; 3rd) month, the next one is a dīng-mǎo (丁卯; 4th) month, etc., and the last month of the year is a dīng-chǒu (丁丑, 14th) month. The next year will start with a wù-yín (戊寅; 15th) month, etc. following the cycle. The 5th year will end with a yǐ-chǒu (乙丑; 2nd) month. The following month, the start of a or jiǎ year, will hence again be a bǐng-yín (3rd) month again. The beginning and end of the (solar) months in the table below are the approximate dates of current solar terms; they vary slightly from year to year depending on the leap days of the Gregorian calendar.

Earthly Branches of the certain months Solar term Zhongqi (the Middle solar term) Starts at Ends at Names in year of Jia or Ji(/己年) Names in year of Yi or Geng (/庚年) Names in year of Bing or Xin (/辛年) Names in year of Ding or Ren (/壬年) Names in year of Wu or Gui (/癸年)
Month of Yin (寅月) LichunJingzhe Yushui February 4 March 6 Bingyin / 丙寅月 Wuyin / 戊寅月 Gengyin / 庚寅月 Renyin / 壬寅月 Jiayin / 甲寅月

Month of Mao (卯月)

JingzheQingming Chunfen March 6 April 5 Dingmao / 丁卯月 Jimao / 己卯月 Xinmao / 辛卯月 Guimao / 癸卯月 Yimao / 乙卯月
Month of Chen (辰月) QingmingLixia Guyu April 5 May 6 Wuchen / 戊辰月 Gengchen / 庚辰月 Renchen / 壬辰月 Jiachen / 甲辰月 Bingchen / 丙辰月
Month of Si (巳月) LixiaMangzhong Xiaoman May 6 June 6 Jisi / 己巳月 Xinsi / 辛巳月 Guisi / 癸巳月 Yisi / 乙巳月 Dingsi / 丁巳月
Month of Wu (午月) MangzhongXiaoshu Xiazhi June 6 July 7 Gengwu / 庚午月 Renwu / 壬午月 Jiawu / 甲午月 Bingwu / 丙午月 Wuwu / 戊午月
Month of Wei (未月) XiaoshuLiqiu Dashu July 7 August 8 Xinwei / 辛未月 Guiwei / 癸未月 Yiwei / 乙未月 Dingwei / 丁未月 Jiwei / 己未月
Month of Shen (申月) LiqiuBailu Chushu August 8 September 8 Renshen / 壬申月 Jiashen / 甲申月 Bingshen / 丙申月 Wushen / 戊申月 Gengshen / 庚申月
Month of You (酉月) BailuHanlu Qiufen September 8 October 8 Guiyou / 癸酉月 Yiyou / 乙酉月 Dingyou / 丁酉月 Jiyou / 己酉月 Xinyou / 辛酉月
Month of Xu (戌月) HanluLidong Shuangjiang October 8 November 7 Jiaxu / 甲戌月 Bingxu / 丙戌月 Wuxu / 戊戌月 Gengxu / 庚戌月 Renxu / 壬戌月
Month of Hai (亥月) LidongDaxue Xiaoxue November 7 December 7 Yihai / 乙亥月 Dinghai / 丁亥月 Jihai / 己亥月 Xinhai / 辛亥月 Guihai / 癸亥月
Month of Zi (子月) DaxueXiaohan Dongzhi December 7 January 6 Bingzi / 丙子月 Wuzi / 戊子月 Gengzi / 庚子月 Renzi / 壬子月 Jiazi / 甲子月
Month of Chou (丑月) XiaohanLichun Dahan January 6 February 4 Dingchou / 丁丑月 Jichou / 己丑月 Xinchou / 辛丑月 Guichou / 癸丑月 Yichou / 乙丑月

## Sexagenary days

Table for sexagenary days
Day
(stem)
Month
(stem)
2-digit year
mod 40
(stem)
Century
(stem)
N Century
(branch)
2-digit year
mod 16
(branch)
Month
(branch)
Day
(branch)
Julian
mod 2
Gregorian Julian
mod 4
Gregorian
00 10 20 30 Aug 00 02 21 23 00 16 00 00 00 07 Nov 00 12 24
01 11 21 31 Sep Oct 04 06 25 27 21 01 14 01 13 25
02 12 22 Nov Dec 08 10 29 31 19 02 16 19 05 Feb Apr 02 14 26
03 13 23 12 14 33 35 03 03 22 03 12 Feb Jun 03 15 27
04 14 24 16 18 37 39 17 24 04 10 Aug 04 16 28
05 15 25 01 03 20 22 01 22 15 05 15 01 Oct 05 17 29
06 16 26 05 07 24 26 06 02 18 08 15 Dec 06 18 30
07 17 27 Mar Jan 09 11 28 30 20 07 21 06 Jan Mar 07 19 31
08 18 28 Jan Apr May Feb 13 15 32 34 18 08 24 13 Jan May 08 20
09 19 29 Feb Jun Jul 17 19 36 38 23 09 01 04 11 Jul 09 21
Dates with the pale yellow background indicate they are for this year. 10 17 02 10 22
11 20 23 09 Sep 11 23
• N for the year: (5y + [y/4]) mod 10, y = 0–39 (stem); (5y + [y/4]) mod 12, y = 0–15 (branch）
• N for the Gregorian century: (4c + [c/4] + 2) mod 10 (stem); (8c + [c/4] + 2) mod 12 (branch), c ≥ 15
• N for the Julian century: 5c mod 10, c = 0–1 (stem); 9c mod 12, c = 0–3 (branch)

The table above allows one to find the stem & branch for any given date. For both the stem and the branch, find the N for the row for the century, year, month, and day, then add them together. If the sum for the stems' N is above 10, subtract 10 until the result is between 1 and 10. If the sum for the branches' N is above 12, subtract 12 until the result is between 1 and 12.

For any date before October 15, 1582, use the Julian century column to find the row for that century's N. For dates after October 15, 1582, use the Gregorian century column to find the century's N. When looking at dates in January and February of leap years, use the bold & italic Feb and Jan.

### Examples

• Step-by-step example to determine the stem-branch for October 1, 1949.
• Stem
• (day stem N + month stem N + year stem N + century stem N) = number of stem. If over 10, subtract 10 until within 1 - 10.
• Day 1: N = 1,
• Month of October: N = 1,
• Year 49: N = 7,
• 49 isn't on the table, so we'll have to mod 49 by 40. This gives us year 9, which we can follow to find the N for that row.
• Century 19: N = 2.
• (1 + 1 + 7 + 2) = 11. This is more than 10, so we'll subtract 10 to bring it between 1 and 10.
• 11 - 10 = 1,
• Stem = 1, .
• Branch
• (day branch N + month branch N + year branch N + century branch N)= number of branch. If over 12, subtract 12 until within 1 - 12.
• Day 1: N = 1,
• Month of October: N = 5,
• Year 49: N = 5,
• Again, 49 is not in the table for year. Modding 49 by 16 gives us 1, which we can look up to find the N of that row.
• Century 19: N = 2.
• (1 + 5 + 5 + 2) = 13. Since 13 is more than 12, we'll subtract 12 to bring it between 1 and 12.
• 13 - 12 = 1,
• Branch = 1, .
• Stem-branch = 1, 1 (甲子, 1 in sexagenary cycle = 32 - 5 + 33 + 1 - 60).
More detailed examples
• Stem-branch for December 31, 1592
• Stem = (day stem N + month stem N + year stem N + century stem N)
• Day 31: N = 1; month of December: N = 2; year 92 (92 mod 40 = 12): N = 3; century 15: N = 5.
• (1 + 2 + 3 + 5) = 11; 11 - 10 = 1.
• Stem = 1, .
• Branch = (day branch N + month branch N + year branch N + century branch N)
• Day 31: N = 7; month of December: N = 6; year 92 (92 mod 16 = 12): N = 3; century 15: N = 5.
• (7 + 6 + 3 + 5) = 21; 21 - 12 = 9.
• Branch = 9,
• Stem-branch = 1, 9 (甲申, 21 in cycle = - 42 - 2 + 34 + 31 = 21)
• Stem-branch for August 4, 1338
• Stem = 8,
• Day 4: N = 4; month of August: N = 0; year 38: N = 9; century 13 (13 mod 2 = 1): N = 5.
• (4 + 0 + 9 + 5) = 18; 18 - 10 = 8.
• Branch = 12,
• Day 4: N = 4; month of August: N = 4; year 38 (38 mod 16 = 6): N = 7; century 13 (13 mod 4 = 1): N = 9.
• (4 + 4 + 7 + 9) = 24; 24 - 12 = 12
• Stem-branch = 8, 12 (辛亥, 48 in cycle = 4 + 8 + 32 + 4)
• Stem-branch for May 25, 105 BC (-104).
• Stem = 7,
• Day 25: N = 5; month of May: N = 8; year -4 (-4 mod 40 = 36): N = 9; century -1 (-1 mod 2 = 1): N = 5.
• (5 + 8 + 9 + 5) = 27; 27 - 10 = 17; 17 - 10 = 7.
• Branch = 3,
• Day 25: N = 1; month of May: N = 8; year -4 (-4 mod 16 = 12): N = 3; century -1 (-1 mod 4 = 3): N = 3.
• (1 + 8 + 3 + 3) = 15; 15 - 12 = 3.
• Stem-branch = 7, 3 (庚寅, 27 in cycle = - 6 + 8 + 0 + 25)
• Alternately, instead of doing both century and year, one can exclude the century and simply use -104 as the year for both the stem and the branch to get the same result.

### Algorithm for mental calculation

${\displaystyle SB=(y+c+m+day){\bmod {6}}0}$
${\displaystyle S=SB{\bmod {1}}0,B=SB{\bmod {1}}2}$
${\displaystyle y=(year({\bmod {4}}00){\bmod {8}}0({\bmod {1}}2)\times 5+\left\lfloor {\frac {year({\bmod {4}}00){\bmod {8}}0}{4}}\right\rfloor ){\bmod {6}}0}$
${\displaystyle c=\left\lfloor {\frac {year}{400}}\right\rfloor -\left\lfloor {\frac {year}{100}}\right\rfloor +10}$ for Gregorian calendar and ${\displaystyle c=8}$ for Julian calendar.
${\displaystyle m=(month+1){\bmod {2}}\times 30+\left\lfloor {0.6\times (month+1)-3}\right\rfloor -i}$
${\displaystyle i=5}$ for Jan or Feb in a common year and ${\displaystyle i=6}$ in a leap year.
 Month m Leap year Jan13 Feb14 Mar03 Apr04 May05 Jun06 Jul07 Aug08 Sep09 Oct10 Nov11 Dec12 00 31 -1 30 00 31 01 32 03 33 04 34 -1 30 ${\displaystyle m=\left\lfloor {30.6\times (month+1)}-3\right\rfloor {\bmod {6}}0-i}$
• Stem-branch for February 22, 720 BC (-719).
y = 5 x (720 - 719) + [1/4] = 5
c = 8
m = 30 + [0.6 x 15 - 3] - 5 = 31
d = 22
SB = 5 + 8 + 31 + 22 - 60 = 6
S = B = 6, 己巳
• Stem-branch for November 1, 211 BC (-210).
y = 5 x (240 - 210) + [30/4] = 5 x 6 + 7 = 37
c = 8
m = 0 + [0.6 x 12 - 3] = 4
d = 1
SB = 37 + 8 + 4 + 1 = 50
S = 0, B = 2, 癸丑
• Stem-branch for February 18, 1912.
y = 5 x (1912 - 1920) + [-8/4] + 60 = 18
c = 4 - 19 + 10 = -5
m = 30 + [0.6 x 15 - 3] - 6 = 30
d = 18
SB = 18 - 5 + 30 + 18 - 60 = 1
S = B = 1, 甲子
• Stem-branch for October 1, 1949.
y = 5 x (1949 - 1920) + [29/4] = 5 x 5 + 7 = 32
c = -5
m = 30 + [0.6 x 11 -3] = 33
d = 1
SB = 32 - 5 + 33 + 1 - 60 = 1
S = B = 1, 甲子

## Sexagenary hours

Table for sexagenary hours (5-day cycle)
Stem of the day Zǐ hour

23:00–1:00
Chǒu hour

1:00–3:00
Yín hour

3:00–5:00
Mǎo hour

5:00–7:00
Chén hour

7:00–9:00
Sì hour

9:00–11:00
Wǔ hour

11:00–13:00
Wèi hour

13:00–15:00
Shēn hour

15:00–17:00
Yǒu hour

17:00–19:00
Xū hour

19:00–21:00
Hài hour

21:00–23:00
Jia or Ji day
(甲/己)
1 甲子 2乙丑 3 丙寅 4 丁卯 5 戊辰 6 己巳 7 庚午 8 辛未 9 壬申 10 癸酉 11 甲戌 12 乙亥
Yi or Geng day
(乙/庚)
13 丙子 14 丁丑 15 戊寅 16 己卯 17 庚辰 18 辛巳 19 壬午 20 癸未 21 甲申 22 乙酉 23 丙戌 24 丁亥
Bing or Xin day
(丙/辛)
25 戊子 26 己丑 27 庚寅 28 辛卯 29 壬辰 30 癸巳 31 甲午 32 乙未 33 丙申 34 丁酉 35 戊戌 36 己亥
Ding or Ren day
(丁/壬)
37 庚子 38 辛丑 39 壬寅 40 癸卯 41 甲辰 42 乙巳 43 丙午 44 丁未 45 戊申 46 己酉 47 庚戌 48 辛亥
Wu or Gui day
(戊/癸)
49 壬子 50 癸丑 51 甲寅 52 乙卯 53 丙辰 54 丁巳 55 戊午 56 己未 57 庚申 58 辛酉 59 壬戌 60 癸亥

## References

### Citations

1. ^ Nussbaum, Louis-Frédéric (2005). "Jikkan-jūnishi". Japan Encyclopedia. Translated by Roth, Käthe. p. 420.
2. ^ Smith 2011, pp. 1, 28.
3. ^ For the Akan calendar, see (Bartle 1978).
4. ^ Smith 2011, pp. 24, 26-27.
5. ^ Kalinowski 2007, p. 145, fig. 3.
6. ^ Smith 2011, p. 29.
7. ^ Smith 2011, p. 28.
8. ^ "Calendar History; the Source". National Diet Library. Archived from the original on January 6, 2013. Retrieved January 1, 2013.
9. ^ "Kanreki". Encyclopedia of Shinto. Retrieved January 1, 2013.
10. ^ Chattopadhyaya, Alaka (1999). Atisa and Tibet: Life and Works of Dipamkara Srijnana in relation to the history and religion of Tibet. pp. 566–568.
11. ^ Aslaksen, Helmer (July 17, 2010). "Mathematics of the Chinese calendar" (PDF). www.math.nus.edu.sg/aslaksen. Department of Maths, National University of Singapore.
12. ^ Smith 2011, pp. 28, 29 fn2.
13. ^ 建す. Kōjien. Tokyo: Iwanami Shoten.
14. ^ "Records part 6" 本紀第六 肅宗 代宗. Xīn Tángshū 新唐書 [New Book of Tang]. 二年……，九月壬寅，大赦，去「乾元大圣光天文武孝感」号，去「上元」号，称元年，以十一月为岁首，月以斗所建辰为名。赐文武官阶、勋、爵，版授侍老官，先授者叙进之。停四京号。
元年建子月癸巳，曹州刺史常休明及史朝义将薛崿战，败之。己亥，朝圣皇天帝于西内。丙午，卫伯玉及史朝义战于永宁，败之。己酉，朝献于太清宫。庚戌，朝享于太庙及元献皇后庙。建丑月辛亥，有事于南郊。己未，来瑱及史朝义战于汝州，败之。乙亥，侯希逸及朝义将李怀仙战于范阳，败之。宝应元年建寅月甲申，追册靖德太子琮为皇帝，妃窦氏为皇后。乙酉，葬王公妃主遇害者。丙戌，盗发敬陵、惠陵。甲辰，李光弼克许州。吐蕃请和。戊申，史朝义陷营州。建卯月辛亥，大赦。赐文武官阶、爵。五品以上清望及郎官、御史荐流人有行业情可矜者。停贡鹰、鹞、狗、豹。以京兆府为上都，河南府为东都，凤翔府为西都，江陵府为南都，太原府为北都。壬子，羌、浑、奴剌寇梁州。癸丑，河东军乱，杀其节度使邓景山，都知兵马使辛云京自称节度使。乙丑，河中军乱，杀李国贞及其节度使荔非元礼。戊辰，淮西节度使王仲升及史朝义将谢钦让战于申州，败绩。庚午，敦子仪知朔方、河中、北庭、潞仪泽沁节度行营，兴平、定国军兵马副元帅。壬申，鄜州刺史成公意及党项战，败之。建辰月壬午，大赦，官吏听纳赃免罪，左降官及流人罚镇效力者还之。甲午，奴剌寇梁州。戊申，萧华罢。户部侍郎元载同中书门下平章事。建巳月庚戌，史朝义寇泽州，刺史李抱玉败之。壬子，楚州献定国宝玉十有三。甲寅，圣皇天帝崩。乙丑，皇太子监国。大赦，改元年为宝应元年，复以正月为岁首，建巳月为四月。丙寅，闲厩使李辅国、飞龙厩副使程元振迁皇后于别殿，杀越王系、兗王亻闲。是夜，皇帝崩于长生殿，年五十二。查《壽星萬年曆》，
唐肅宗之元年
冬至所在月（761.12）：初一壬午大雪，十三癸巳，十七冬至，十九己亥，廿五丙午，廿八己酉，廿九庚戌
大寒所在月（762.02）：初一辛亥，初三小寒，初九己未，十八大寒，廿五乙亥
雨水所在月（762.03）：初一辛巳，初三立春，初四甲申，初五乙酉，初六丙戌，十八雨水，廿四甲辰，廿八戊申
春分所在月（762.3）：初一辛亥，初四驚蜇，初二壬子，初三癸丑，十五乙丑，十八戊辰，十九春分，二十庚午，廿一壬申，
穀雨所在月（762.4）：初一庚辰，初三壬午，初五清明，十五甲午，二十穀雨，廿九戊申
小滿所在月（762.5）：初一庚戌，初三壬子，初五甲寅立夏，初五乙丑，十六丙寅。
大寒所在月初一辛亥，已稱建丑月，初三才小寒
春分所在月初一辛亥，已稱建卯月，初四才驚蜇
穀雨所在月初三壬午，已稱建辰月，初五才清明
小滿所在月初一庚戌、初三壬子，已稱建巳月，初五才立夏
由此可見，唐代地支紀月自朔日始，非自節氣始。
15. ^ 三正, Kōjien, Toyko: Iwanami Shoten

### Sources

• Bartle, P. F. W. (1978). "Forty days: the Akan calendar". Africa: Journal of the International African Institute. 48 (1): 80–84. doi:10.2307/1158712. JSTOR 1158712.
• Kalinowski, Marc (2007). "Time, space and orientation: figurative representations of the sexagenary cycle in ancient and medieval China". In Francesca Bray. Graphics and text in the production of technical knowledge in China : the warp and the weft. Leiden: Brill. pp. 137–168. ISBN 978-90-04-16063-7.
• Smith, Adam (2011). "The Chinese sexagenary cycle and the ritual origins of the calendar". In John Steele. Calendars and years II : astronomy and time in the ancient and medieval world. Oxford: Oxbow. pp. 1–37. ISBN 978-1-84217-987-1.