Julian Day Converter
Convert between Gregorian/Julian calendar dates and Julian Day Numbers (JD) · Essential for astronomical calculations
Calendar → Julian Day
Julian Day → Calendar
Julian Day Number (JD)
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Enter a date to see Julian Day
Julian Day (JD) is the continuous count of days since noon Universal Time on January 1, 4713 BCE (Julian calendar).
JD 2460450.0 = 2026-04-21 12:00 UT. The fractional part represents the time of day (0.5 = midnight).