Julian Date Converter

Convert any calendar date to its Julian Day Number — the astronomers' day count.

Date:

How to use

Pick a date, then click Convert.

What is a Julian Day Number?

Days counted continuously since noon on January 1, 4713 BC — used in astronomy and date math.

Is this the same as a Julian calendar date?

No — the Julian calendar is the old Roman calendar; the Julian Day Number is a continuous count.

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