### Calculating Number of Working Days

You can use the NETWORKDAYS() function in Excel to calculate the number of working days (excluding weekends) between and including two dates.

`=NETWORKDAYS(start_date,end_date,holidays)`

In Excel 2000/2002/2003, this function requires the Analysis ToolPak to be installed. The start_date and end_date must be dates stored as serial numbers or defined using the DATE function. The holidays parameter is optional and is a reference to range of dates to be excluded besides weekends.

Example:
```A1=1/1/2009    (Start Date)
A2=1/8/2009    (End Date)
A3=1/1/2009    (Holiday)
A4=1/2/2009    (Non-Working Day)
A5=NETWORKDAYS(A1,A2)        (= 6 Working Days)
A6=NETWORKDAYS(A1,A2,A3:A4)  (= 4 Working Days)```

The WORKDAY() function is almost the reverse of the NETWORKDAYS function, except that the WORKDAY function finds the date that is the number of days before or after the start_date, but not including the start date.
`=WORKDAY(start_date,days,holidays)`

Example:
`=WORKDAY(A1,6)   (= 1/9/2009)`