To include the TIME in the Julian Date conversion, you can use a couple of different formulas to add in the day-fraction for a time specified as HH:MM:SS (24-hour Greenwich Mean Time):
Keep in mind that the Gregorian calendar starts on 1. Using the formula from, the Julian Date for any date in the Gregorian calendar (at 0:00 GMT) can be calculated using: The problem is that this only works for years after 1901. Where Y is the year, M is the month, and D is the day, and DATE( Y, M, D) could be replaced with just a standard Excel date. The Excel help documentation suggests using the following conversion to calculate a Julian Date: Also, Excel dates correspond to the Gregorian Calendar (established in 1582). Note that UT (Universal Time) is typically known as GMT (Greenwich Mean Time). Julian Date calculated as # of Days Since Noon (UT), BC Julian Date (Julian Day Number) Conversions A better way in my opinion is converting from the format "yyyyddd" which avoids having to use the century variable, and datetext can be numeric: and datetext is the date in the format "yyddd". This can be done using the following julian date conversion formula:
Note that standard Excel dates ( xldate) are only defined between and December 31, 9999, so formulas that use Excel's built-in date functions will likely only work in this range.Ĭonvert a date in the form "yyddd" to a Standard Date. When using the format "yyyyddd", you can replace "yy" with "yyyy" in the above formula, or because there are no leading zeros, you don't have have to treat the Ordinal date as text, leading to the following formula: (Due to Y2K, this isn't a very safe format. "Ordinal Dates" in the form yyddd or yyyyddĬonvert a Standard Date to the date format "yyddd". " Julian Calendar." From MathWorld-A Wolfram Web Resource. " Julian Date." From MathWorld-A Wolfram Web Resource.Įric W.
Peter Meyer's article, " Julian Day Number" includes references suggesting that the third use should no longer be used and that the more official term for the "day of the year" is "Ordinal Date".
There are three main uses of the term "Julian Date": (1) A date in the Julian Calendar (2) Another term for " Julian Day Number" which is the number of days since noon GMT on BC, and (3) A common date format used in the computer indusry " yyyyddd" or " yyddd".