Julian Date Converter
Convert a calendar date to its Julian day number, or a Julian day number back to a calendar date — the numbering astronomers and many systems use.
Julian day number: 2461356.00000
Julian day starts at noon UTC, so 12:00 UTC is an exact .0 — midnight UTC is .5.
Gregorian date: Thursday, November 20, 2025 at 12:00 UTC
How it works: the Fliegel–Van Flandern algorithm converts between the proleptic Gregorian calendar and the Julian day count (days since noon, 1 January 4713 BC). The fractional part is the time of day from noon UTC.
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