How to Calculate the Days of the Year in Excel

An easy formula that returns the day of the year for a given date. There's no built-in function in Excel that can do this.

1. Enter the formula shown below.

Explanation: Dates and times are stored as numbers in Excel and count the number of days since January 0, 1900. June 23, 2012 is the same as 41083. The DATE function accepts three arguments: year, month and day. DATE(YEAR(A1),1,1) or 1-jan-2012 is the same as 40909. Subtracting these numbers (41083 - 40909 = 174) and adding 1 gives the day of the year.