# How to Use Excel's WEEKDAY Function

How to Use Excel's WEEKDAY Function. Excel's WEEKDAY function calculates the day of the week for the specified date. It returns an integer ranging from 1 to 7 corresponding to the days of the week. Date conversion functions are needed by spreadsheets because dates are frequently an essential factor in data analysis. The following steps will show how to use Excel's WEEKDAY function.

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Learn the syntax for WEEKDAY. It is WEEKDAY(serial_number, return_type).

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Provide serial_number as a number that represents a date. Enter the date using the DATE function or some other means to ensure serial_number is a valid date.

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Understand the internal format Excel uses to store dates. The date is stored as the integer representing the number of days that have passed since December 31, 1899 in Excel for Windows. Excel for Macintosh bases its dating from January 1, 1904. This system allows dates to be easily manipulated.

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Specify return_type to determine the type of the return value. A return type of 1 means that 1 will be used for Sunday through 7 for Saturday. A return type of 2 means that 1 will be used for Monday through 7 for Sunday. A return type of 3 means that 0 will be used for Monday through 6 for Sunday. Return_type may be omitted and defaults to 1.

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Look at some examples of how to use WEEKDAY. If A2 = 10/02/2007, which is a Tuesday, we have:

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WEEKDAY(A2) = 3 WEEKDAY(A2,2) = 2 WEEKDAY(A2,3) = 1