Kanseirei (Kansei Calendar) (寛政暦)

The Kanseirei (Kansei calendar) is a Japanese lunar-solar calendar, formerly used in Japan.


Japanese calendar dates are in old lunar calendar style. The Christian Era and dates are in the Gregorian calendar style.

Duration of use

The Kanseireki (Kansei calendar) replaced the Horyakureki (Horyaku calendar) on February 16, 1798, and was used for 46 years until February 17, 1844.

It was reformed to the Tenporeki (Tenpo calendar) on February 18, 1844.


Because the Horyakureki (Horyaku calendar) was deemed to be inadequate, the bakufu (Japanese feudal government headed by a shogun) decided to replace it with a new calendar by adopting Western astronomy; consequently, the bakufu employed Yoshitoki TAKAHASHI as the "Bakufu Tenmongata" (official astronomer to a shogun) and asked him to reform the calendar with Shigetomi HAZAMA, an astronomer who had studied under the same teacher. TAKAHASHI and his colleagues cooperated with a former Tenmongata (Toshitsugu YAMAJI and others) to complete a new calendar in 1797. This rekiho adopted the theory that the orbit of the sun and the moon is ellipse and the method that formulated a periodical variation of astronomical constants in calculating the celestial movement, based on "Rekisho kosei kohen (A Complete Carendrical Treatise on the Method of Calculating the Celestial Movement: a Sequel to the Former Work)," a translation of the Chinese version of Western astronomy books.

"Kansei Rekisho (Expository Book in the Kansei Calendar)" (35 volumes) was published by Kagesuke SHIBUKAWA in 1844. The book includes some charts illustrated by Tycho Brahe.

In the Daishoreki (Daishoreki calendar which shows only the order of the long and short months) of the year, 1873, (a long month (with 30 days), a short month (with 29 days)), the long months were ni (number 2)-gatsu (February), shi (number 4)-gatsu (April), roku (number 6)-gatsu (June), ku (number 9)-gatsu (September), and juichi (number 11)-gatsu (November), and a mnemonic rhyme for remembering the long months of the year was 'nishimuku samurai' (meaning a samurai facing the west with the identical pronunciation as number 2 (ni), 4 (shi), 6 (mu; number six can be expressed as 'mu' as well as 'roku'), and 9 (ku) and the last number 11 is written in kanji (Chinese characters) 十 (meaning ten) and 一 (meaning one), and when they are written vertically, the result resembles the kanji 士 (meaning samurai), which also means that ten plus one is eleven).

Incidentally, the long months in the year of 1825 were January, March, May, July, October, and December and a mnemonics for remembering the long months of the year was "daisukiha zoni, kusamochi, kashiwamochi, bon no boatamochi, inoko, kanmochi" (meaning "What I like is zoni (vegetable soup containing mochi (rice cake), eaten on January 1), kusamochi (rice-flour dumplings mixed with mugwort, eaten on March 3), kashiwamochi (a rice cake which contains bean paste and is wrapped in an oak leaf, eaten May 5), botamochi of the Obon festival (a rice ball coated with sweetened red beans, soybean flour, or sesame, eaten on the day of Obon festival (Festival of the Dead or Buddhist All Soul's Day in mid July)), inokomochi (rice cake like a little boar, eaten on the day of boar in October), and kanmochi (rice cake pounded during the coldest season in December (around present-day January)).

[Original Japanese]