Explanation
The DATE function builds dates from separate year, month, and day values. One of its tricks is the ability to roll forward to correct dates when given days and months that are "out of range". For example, DATE returns April 9, 2016, with the following arguments:
=DATE(2016,1,100)
There is no 100th day in January, so DATE simply moves forward 100 days from January 1 and returns the correct date.
The formula on this page takes advantage of this behavior. The year is assumed to be 2015 in this case, so 2015 is hard-coded for the year, and 1 is used for the month. The day value comes from column B, and the DATE function calculates the date as explained above.
Extracting a year value from a Julian date
If you have a date in a Julian format, for example, 10015, where the format is "dddyy", you can adapt the formula as follows:
=DATE(RIGHT(A1,2),1,LEFT(A1,3))
Here, we use RIGHT to extract the 2 characters from the right for the year, and LEFT to extract 3 characters from the left for the day. The month is supplied as 1, as in the first example.
Related formulas
Convert date to Julian format
Related functions
DATE Function
The Excel DATE function creates a valid date from individual year, month, and day components. The DATE function is useful for assembling dates that need to change dynamically based on other values in a worksheet.
RIGHT Function
The Excel RIGHT function extracts a given number of characters from the right side of a supplied text string. For example, =RIGHT("apple",3) returns "ple".
LEFT Function
The Excel LEFT function extracts a given number of characters from the left side of a supplied text string. For example, =LEFT("apple",3) returns "app".
