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Let's say you want find out how many days a customer takes to pay a bill or how long it takes to ship a product upon receipt of an approved order. There are several ways to calculate the difference between two dates.
What do you want to do?
Calculate the number of days between two dates
Calculate the number of months between two dates
Calculate the number of years between two dates
Calculate the number of days between two dates
To do this task, use the subtraction () operator or the NETWORKDAYS function.
If the NETWORKDAYS function is not available, install and load the Analysis ToolPak addin.
How?
 On the Tools menu, click AddIns.
 In the AddIns available list, select the Analysis ToolPak box, and then click OK.
 If necessary, follow the instructions in the setup program.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example
 Create a blank workbook or worksheet.
 Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help
 Press CTRL+C.
 In the worksheet, select cell A1, and press CTRL+V.
 To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Tools menu, point to Formula Auditing, and then click Formula Auditing Mode.

A 
Date 
6/8/2007 
6/20/2007 
Formula 
Description 
=A3A2 
Days between the two dates (12) 
=NETWORKDAYS(A2,A3) 
Weekdays between the two dates (9) 

Note To view the dates as numbers, select the cell and click Cells on the Format menu. Click the Number tab, and then click Number in the Category box.
Function details
NETWORKDAYS
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Calculate the number of months between two dates
To do this task, use the MONTH and YEAR functions.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example
 Create a blank workbook or worksheet.
 Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help
 Press CTRL+C.
 In the worksheet, select cell A1, and press CTRL+V.
 To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Tools menu, point to Formula Auditing, and then click Formula Auditing Mode.

A 
Date 
6/9/2007 
9/2/2007 
12/10/2008 
Formula 
Description (Result) 
=MONTH(A3)MONTH(A2) 
Months occurring between two dates in the same year (3) 
=(YEAR(A4)YEAR(A3))*12+MONTH(A4)MONTH(A3) 
Months occurring between two dates over a year apart (15) 

Note To view the dates as numbers, select the cell and click Cells on the Format menu. Click the Number tab, and then click Number in the Category box.
Function details
MONTH
YEAR
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Calculate the number of years between two dates
To do this task, use the YEAR function.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example
 Create a blank workbook or worksheet.
 Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help
 Press CTRL+C.
 In the worksheet, select cell A1, and press CTRL+V.
 To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Tools menu, point to Formula Auditing, and then click Formula Auditing Mode.

A 
Date 
6/9/2007 
6/4/2010 
Formula 
Description (Result) 
=YEAR(A3)YEAR(A2) 
Years occurring between two dates (3) 

Notes
 To view the dates as numbers, select the cell and click Cells on the Format menu. Click the Number tab, and then click Number in the Category box.
 You cannot subtract a date that is later than another date, or the error #### appears in the cell.
Function details
YEAR
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