Conversion from ISO 8601 year-month-day to Modified Julian Date (day number).

MJD = JD - 2400000.5

See Template talk:YMD2MJD for more documentation and test suites.

Usage:
{{YMD2MJD|year|[month]|[day]|[hour]|[minute]|[seconds]}}
{{YMD2MJD}}
Examples using only the Julian (including proleptic) calendar:
{{YMD2MJD|-4712|01|01|12|00|00}} = -2399998.5, 1 January 4713 BC 12:00 UTC (JD = 0)
{{YMD2MJD|-0100|02|29}} = -715407, 29 February 101 BC
{{YMD2MJD|-0100|03|01}} = -715406, 1 March 101 BC (proleptic Julian leap year)
{{YMD2MJD|-0100|03|02}} = -715405, 2 March 101 BC
{{YMD2MJD|-0000|02|28}} = -678883, 28 February 1 BC
{{YMD2MJD|-0000|02|29}} = -678882, 29 February 1 BC
{{YMD2MJD|0000|03|01}} = -678881, 1 March 1 BC
{{YMD2MJD|0000|12|31}} = -678576, 31 December 1 BC (Astronomical year numbering)
{{YMD2MJD|0001|01|01}} = -678575, begin Common Era
{{YMD2MJD|0200|02|29}} = -605832, this and earlier dates are Julian
Examples in the 3rd century using the Julian or (proleptic) Gregorian calendar:
{{YMD2MJD|0200|03|01}} = -605831, first Julian = Gregorian date
{{YMD2MJD|0300|02|28}} = -569310, last Julian = Gregorian date
Examples using only the Gregorian (including proleptic) calendar:
{{YMD2MJD|0300|03|01}} = -569309, this and later dates are Gregorian
{{YMD2MJD|1858|11|17}} = 0, begin of MJD epoch
{{YMD2MJD|1900|02|28}} = 15078, last day of February 1900
{{YMD2MJD|1900|02|29}} = 15079, bogey but okay
{{YMD2MJD|1900|03|01}} = 15079, no leap year
{{YMD2MJD|1900|02|30}} = 15080, bogey but okay
{{YMD2MJD|1900|03|02}} = 15080
{{YMD2MJD|1995|09|27}} = 49987, USNO test date (49987)
{{YMD2MJD|2000|02|29}} = 51603, last day of February 2000
{{YMD2MJD|2000|02|30}} = 51604, bogey but okay
{{YMD2MJD|2000|03|01}} = 51604, leap year
{{YMD2MJD|2000|02|31}} = 51605, bogey but okay
{{YMD2MJD|2000|03|02}} = 51605
{{YMD2MJD|2024|10|07}} = 60590
Example using the current date:
{{YMD2MJD}} gives 60590 [1]