Koka (弘化) was a Japanese era after Tempo and before Kaei and spanned from December 2 (?), 1844 to February 28 (?), 1848. The reigning emperors were Ninko and Komei.
Change of Era
Due to a fire at Edo Castle, on December 2 (?), Tempo 15 (1844), the era was changed to Koka (roughly "Becoming wide/vast")