Zaɓi kwanan wata ko danna "Amfani Yau" don ƙididdige matakan wata takwas, shekarun wata da ma'aunin haske. Kwanakin wata mai zuwa da sabon wata matsakaicin kididdigar lokaci ne kuma bai kamata a yi amfani da su ba don lura ko hukunce-hukuncen kalanda waɗanda ke buƙatar daidaiton matakin mintuna.
Yana ƙididdige kimanin lokacin wata bayan zabar kwanan wata. Kayan aikin yana amfani da ma'anar synodic wata a cikin gida, baya loda kwanan wata, kuma baya kiran ƙirar sararin samaniya na ainihin lokaci.