The MONTH, DAY and YEAR functions are designed to take an Excel serial date number and convert it to a month, day or year number representation. Of great use when building dashboards or worksheet tables that will be used in PivotTables.
The Excel MONTH, DAY and YEAR functions are computer programs that you run from a worksheet cell formula. They convert an Excel date serial number like 42005 in to a month number range from 1-12, a day number range from 1-31 and a year format like 2015. You run these functions by typing their names in a formula then followed by the information they are suppose to use. These worksheet functions are used when you have to tear a date apart by its month, day and year number components. Their components are then used for tasks like logic, lookups, mathematical operations like + and -, and table construction so the tables can be filtered with Excel's data tools like PivotTables, Sort and AutoFilter.
Whenever you type a formula in a worksheet cell, this is called syntax or grammar. The general function syntax for these functions has a format like these when you type them in a worksheet cell:
= MONTH( serial_number )
= DAY( serial_number )
= YEAR( serial_number )
Where serial_number is called the function argument list. Remember, you are running a computer program at this point so the program needs information to operate and that is why there is an argument list. When you see an argument list and you see square brackets [ ] around the argument name, this means the argument is optional and you do not have to include it when typing unless you need it. So for the syntax above, you need to include 1 argument when typing the functions in a worksheet cell formula in order for it to calculate correctly. What argument values can be used are discussed below. Remember functions expect certain things in their argument lists, if you do not put the correct information in the list they will generate an error when run.
Since the MONTH, DAY and YEAR functions are computer programs, they run when you press Enter to enter the formula that contains them. If any of their arguments are wrong, the functions will return an error.
When typing the MONTH, DAY and YEAR functions in a worksheet cell formula, you need to replace the serial_number argument with something that generates the serial number needed. Some typical arguments you can use are:
|Argument Type||Cell Formula||Example Explanation|
|Cell Reference||= MONTH( A1 )||Returns the month number based upon what serial date number is in cell A1. For example if 8/24/2015 was in cell A1 then 8 would be returned|
|Range Reference||= YEAR( A1:A10 )||Returns an array of year numbers based upon the dates in cells A1 to A10|
|Nested Functions||= DAY( DATE( A1, A2, A3 ) )||Returns a day number based upon what values are in cell's A1, A2 and A3. The DATE function is used to return the date serial number that MONTH then uses. Very common argument type for dashboard problems and from data stored in multiple columns|
|Nested Functions||= MONTH( DATEVALUE( "5/28/2015" ) )||Returns a month number based upon the serial date number generated by the DATEVALUE function. The value returned would be 5|
The worksheet seen below contains some typical worksheet formulas that run the YEAR worksheet function. Pay close attention to the argument list and the syntax used to write the formula.
|4||Formula below splices date together from table above using the DATE function, then calculates the year so VLOOKUP can use it to lookup a year in another table. Typical use in a VLOOKUP formula|
|5||= VLOOKUP( YEAR( DATE( C2, A2, B2 ) ), $G$1:$K$100, 3, FALSE )|