Kōka (弘化) was a Japanese era after Tempō and before Kaei and spanned from December 2 (?), 1844 to February 28 (?), 1848. The reigning emperors were Ninkō and Kōmei.

Change of Era

Due to a fire at Edo Castle, on December 2 (?), Tempō 15 (1844), the era was changed to Kōka (roughly "Becoming wide/vast")

Kōka	1st	2nd	3rd	4th	5th
Gregorian	1844	1845	1846	1847	1848