Enter a date and select the calendar system to discover corresponding dates in other calendar systems, day of the week, moon phase, and upcoming religious holidays
Important: The Julian calendar day Thursday, 4 October 1582 was followed by the first day of the Gregorian calendar, Friday, 15 October 1582 in most of Europe, but if you are looking at Russia the date after January 31, 1918 (Julian), became February 14, 1918 (Gregorian).
This comprehensive calendar tool provides accurate conversions between different calendar systems and astronomical information:
Calendar Conversions: Uses professional JavaScript libraries and APIs to ensure accuracy across all calendar systems. The tool handles historical dates from ancient times to the present, accounting for the gradual drift between Julian and Gregorian calendars.
Next Moon Events: Uses Skyfield astronomical library to calculate the exact times of upcoming New Moon and Full Moon events. Instead of guessing the current phase, this provides precise UTC timestamps for when these astronomical events will occur, giving you actionable information for planning observations.
Religious Calendars: For comprehensive religious calendar information, see TrueCalendar which provides Orthodox, Catholic, Islamic, and other religious calendars.
For advanced calendar conversions and historical date calculations, visit Fourmilab's Calendar Converter, which provides comprehensive conversions between many calendar systems including Julian Day Numbers, Hebrew, Islamic, and more.
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