Note that the Common Era dates used here reflect the Julian calendar. This was the calendar in use in the western world until 1582 (CE) when Pope Gregory’s reforms went into effect. Therefore, when converting AH dates to CE dates prior to 1582 CE, the Julian dates are calculated. For dates 5 October 1582 and after, the dates are Gregorian dates. The difference between the Julian and the Gregorian calendars is approximately ten days; that is, 5 October 1582 (Julian date) became 15 October 1582 (Gregorian date).
See also Theo Beer's Calendar Converter for mathematical Gregorian dates.
This page was last modified on 01 Jumāda I 1448 / 13 October 2026 by M. Hozien based on the work of J. Thomann of the Institute of Oriental Studies: Zurich University, 1996