สมการ: Japanese era calculator

If you want to calculate the Era of Japan you have to use the emperor's periode of time he or they has reign.
By this way

Jimmu (50 AD)
Suizei Annei Itoku Kosho Koan (100 AD)
Korei Kogen Kaika (200 AD)
Sujin (219-249)
Suinin (249-280)
Keiko (280-316)
Seimu (316-342)
Chuai (343-346
Oojin (346-395)
Nintoku (395-427)
Richu (427-432)
Hanzei (433-438)
Ingyo (438-453)
Anko (453-456)
Yuryaku (456-479)
Seinei (480-484)
Kenzo (485-487)
Ninken (488-498)
Buretsu (498-506)
Keitai (507-531)
Ankan (531-535)
Senka (535-539)
Kimmei (539-571)
Bidatsu (572-585)
Yomei (585-587)
Sushun (587-592)
Suiko (592-628)
Jomei (629-641)
Kogyoku (642-645)
Kotoku (645-654)
Saimei (655-661)
Tenji (662-671)
Kobun (671-672)
Kemmu (673-686)
Jito (690-697)
Mommu (697-707)
Gemmei (707-715)
Gensho (715-724)
Shomu (724-749)
Koken (749-758)
Junnin (758-764)
Shotoku (764-770)
Konin (770-781)
Kammu (781-806)
Heizei (806-824)
Saga (823-842)
Junna (833-840)
Nimmyo (833-850)
Montoku (850-858)
Seiwa (858-876)
Yozei (877-884)
Koko (884-887)
Uda (887-897)
Daigo (897-930)
Suzaku (930-946)
Murakami (946-967)
Reizei (967-969)
Enyu (969-984)
Kazan (984-986)
Ichijo (986-1011)
Sanjo (1011-1016)
Go-Ichijo (1016-1036)
Go-Suzaku (1036-1045)
Go-Reizei (1045-1068)
Go-Sanjo (1067-1072)
Shirakawa (1072-1086)
Horikawa (1086-1107)
Toba (1107-1123)
Sutoku (1123-1141)
Konoye (1141-1155)
Go-Shirakawa (1156-1158)
Nijo (1159-1165)
Rokujo (1166-1168)
Takakura (1169-1180)
Antoku (1181-1183)
Go-Toba (1184-1198)
Tsuchimikado (1199-1210)
Juntoku (1211-1221)
Chukyo (1221-1221)
Go-Horikawa (1222-1232)
Shijo (1233-1242)
Go-Saga (1243-1246)
Go-Fukakusa (1247-1259)
Kameyama (1260-1274)
Go-Uda (1275-1287)
Fushimi (1288-1298)
Go-Fushimi (1299-1301)
Go-Nijo (1302-1308)
Hanazono (1309-1318)
Go-Daigo (1319-1338)
Go-Murakami (1339-1368)
Chokei (1369-1372)
Go-Kameyama (1373-1392)
Go-Komatsu (1392-1412)
Shoko (1413-1428)
Go-Hanazono (1429-1464)
Go-Tsuchimikado (1465-1500)
Go-Kashiwabara (1501-1526)
Go-Nara (1527-1557)
Oogimachi (1558-1586)
Go-Yozei (1587-1611)
Go-Mi-no-o (1612-1629)
Meisho (1630-1643)
Go-Komyo (1644-1654)
Go-Saiin (1655-1662)
Reigen (1663-1686)
Higashi-yama (1687-1709)
Nakamikado (1710-1735)
Sakuramachi (1736-1746)
Momozono (1746-1762)
Go-Sakuramachi (1763-1770)
Go-Momozono (1771-1779)
Kokaku (1780-1816)
Ninko (1817-1846)
Komei (1847-1866)
Mutsuhito (1866-1912)
Yoshihito (1912-1926)
Hirohito (1926-1989)
Heisei(1989-present)

Example like 1945 A.D. you have to know the emperor Heisei and Hirohito ages periode equal them together. and then minus those equalize. and thencount the Emperor's reign. Example like you wanna know what time that Emperor are reign in 1944 Today is Heisei(19)2008 you have to 1945-2008=65 , So Heisei must be Hirohito so it must be Showa(46) So 1945= Showa(46)