Throughout its history Joseon accepted the calendrical method of China and used calendars based on it. Yet, Joseon did not simply use the calendars pronounced and printed in China, or reprint them in Korea. Joseon government carried out its own calendrical calculations and printed and distributed calendars that were prepared using such calculations. Of course Joseon did not adopt a calendrical method different from that of China: the calendrical work of Joseon calendar specialists stayed within the Chinese calendrical method. Nevertheless, the calendars printed and distributed by the Joseon government were different from the calendars pronounced by Chinese emperors. What were the actual differences between the Joseon and the Chinese calendars? What and how did the Joseon government calculate for their calendars? What was their aim in carrying out such calculations? With these questions in mind, this paper examines the Joseon government’s work of calendrical calculation and publication in the late Joseon period. I will argue that the real purpose of their work was to achieve a calendar that meets the standard of the Chinese calendar, rather than to have ‘our own calendar’ as has often been suggested.